Abstract:
The present inventors succeeded in separating bispecific antibodies that functionally substitute for ligands of type I interferon receptors comprising two types of molecules: AR1 chain and AR2 chain. Furthermore, the present inventors succeeded in producing bispecific antibodies that substitute for the enzyme reaction-accelerating function of blood coagulation factor VIII/activated blood coagulation factor VIII, which bind to both blood coagulation factor IX/activated blood coagulation factor IX and blood coagulation factor X.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]    This application is the National Stage of International Application No. PCT/JP2003/013123, filed on Oct. 14, 2003. 
     
     TECHNICAL FIELD  
       [0002]    The present invention relates to bispecific antibodies that substitute for functional proteins. More specifically, the present invention relates to bispecific antibodies that functionally substitute for ligands of hetero-receptors, bispecific antibodies that substitute for the cofactors which enhance enzymatic reaction, and pharmaceutical compositions comprising the antibodies as an active ingredient. 
       BACKGROUND ART  
       [0003]    Antibodies have received much attention as a medicine because of their high stability in blood and low antigenicity. Of these are bispecific antibodies that can simultaneously recognize two types of antigens. Bispecific antibodies have been proposed for some time; however, only antibodies that simply connect two types of antigens, such as those for retargeting NK cells, macrophages, and T cells (see Non-Patent Document  8 ), have been reported. For example, MDX-210, which is currently under clinical study, is a bispecific antibody that merely retargets FcyRI-expressing monocytes and such to HER- 2 /neu-expressing cancer cells. Thus, so far there are no examples that utilize a bispecific antibody as an alternative means to substitute for an in vivo fluctional protein. 
         [0004]    One example of an in vivo functional protein is the ligand of a receptor. Examples of such ligands are interleukin (IL)-2, 3, 4, 5, 6, 7, 9, 10, 11, 12, 13, and 15, erythropoietin (EPO), growth hormone (GH), granulocyte colony-stimulating factor (G-CSF), thrombopoietin (TPO), granulocyte-macrophage colony-stimulating factor (GM-CSF), macrophage colony-stimulating factor (M-CSF), interferon (IFN-ac IFN-,B IFN-y etc.), ciliary neurotrophic factor (CNTF), leukemia inhibitory factor (LIF), Oncostatin M, Cardiotrophin-  1  (CT-1), and tumor necrosis factor (TNF). 
         [0005]    In these receptors, it is thought that the distance and/or angle of the receptor molecules forming dimers or multimers change upon ligand binding, thus enabling these receptors to transmit signals into cells. In other words, a suitable anti-receptor antibody may become an antibody that can mimic ligand-mediated receptor dimerization or multimerization. 
         [0006]    Monoclonal antibodies that show a ligand-substituting effect towards homodimer-comprising TPO receptors (MPL) (see Patent Document 1 and Non-Patent Document 1), EPO receptors, and GH receptors have already been reported. Respectively, these antibodies are thought to have an effect of recovering thrombocyte count at the time of thrombopenia, an effect of increasing red blood cell count at the time of anemia, and a growth-enhancing effect on dwarfism. Thus, their applications in medicine are expected. 
         [0007]    However, in the case of a heterodimer-forming receptor, which requires the formation of a complex of two or several types of receptor molecules, its ligand function cannot be expected to be substituted by general antibodies. The above-mentioned bispecific antibodies which can recognize two types of receptor molecules with their two arms are thought to be suitable for this purpose, however, no reports have been made. 
         [0008]    Another example of an in vivo functional protein is a cofactor. Examples of cofactors are tissue factor (TF), blood coagulation factor V (F.V), activated blood coagulation factor V (F.Va), blood coagulation factor VIII (F.VIII), activated blood coagulation factor VIII (F.VIIIa), thrombomodulin (TM), protein S (PS), protein Z (PZ), heparin, complement C 4 b, complement regulatory factor H, membrane cofactor protein (MCP), and complement receptor  1  (CR  1 ). 
         [0009]    Of these, F.VIII/F.VIIIa is a cofactor required for sufficient activity expression of F.IXa. Scheiflinger F. et al. discovered that a certain anti-F.IX/F.IXa antibody acts to promote the activation of F.X by F.IXa in a chromogenic assay (see Patent Document  2 ). However, in an assay that examines the ability for coagulation recovery in F.VIII-deficient plasma, the coagulation recovery ability was observed only when F.IXa was added exogenously, but not if this antibody was used alone. 
         [0010]    F.VIIIa has been known to interact not only with F.IXa but also with F.X (see Non- Patent Documents  6  and  7 ). In this respect, the antibody of Scheiflinger F. et al. cannot be said to sufficiently substitute for the function of F.VIII/F.VIIIa, and its activity also seems to be insufficient. 
         [0011]    Through dedicated research, the present inventors succeeded in producing bispecific antibodies that substitute for the effect of finctional proteins, and thereby completed this invention.
   (Patent Document 1) U.S. Patent Application No. 98/17364   (Patent Document 2) WO 01/19992   (Patent Document 3) U.S. Pat. No. 4,474,893   (Patent Document 4) EP 404,097   (Patent Document  5 ) WO  93 / 11161     (Patent Document  6 ) Japanese Patent Application No.  2002 - 112369     (Patent Document  7 ) Japanese Patent Application No.  2003 - 012648     (Patent Document  8 ) Japanese Patent Application Kokai Publication No. (JP-A) H 5 - 304992     (Patent Document  9 ) JP-A H 2 - 145187     (Patent Document  10 ) JP-A H 5 - 213775     (Patent Document  11 ) JP-A H  10 - 165184     (Patent Document  12 ) JP-A HI  1 - 71288     (Patent Document  13 ) Japanese Patent Kohyo Publication No. (JP-A)  2002 - 518041     (Patent Document  14 ) JP-A HI  1 - 506310     (Patent Document  15 ) JP-A H 5 - 199894     (Patent Document  16 ) JP-A H 1 O- 511085     (Patent Document  17 ) JP-A H 5 - 184383     (Non-Patent Document  1 ) Deng D et al., “Blood”,  1998 , Vol. 92 , No. 6 , p. 1981 - 1988     (Non-Patent Document  2 ) Nilsson IM et al., “J. Intern. Med.”,  1992  Vol. 235 , p. 25 - 32     (Non-Patent Document  3 ) Lbfqvist T et al., “J. Intern. Med.”,  1997  Vol. 241 , p. 395 - 400     (Non-Patent Document  4 )  24 th Meeting of The Japanese Society on Thrombosis and Hematosis, Special Committee on Examining Hemophilia Standardization, Mini-symposium,  2001 , http://www.jsth.org   (Non-Patent Document  5 ) Bulletin # 193   1994     (Non-Patent Document  6 ) Mertens K et al., “Thromb. Haemost.”,  1999 , Vol. 82 , p. 209 - 217     (Non-Patent Document  7 ) Lapan KA et al., “Thromb. Haemost.”,  1998 , Vol. 80 , p. 418 - 422     (Non-Patent Document  8 ) Segal DM et al., “Journal of Immunological Methods”,  2001 , Vol. 248 , p. 1 - 6     (Non-Patent Document  9 ) Bos R and Nieuwenhuitzen W, “Hybridoma”,  1992 , Vol.  1 , No. 1 , p. 41 - 51     (Non-Patent Document  10 ) Brennan M et al., “Science”,  1985 , Vol. 229 , No. 1708 , p. 81 - 3     (Non-Patent Document  11 ) Karpovsky B et al., “J. Exp. Med.”,  1984 , Vol. 160 , No. 6 , p.  1686 - 701     (Non-Patent Document  12 ) Suresh MR et al., “Methods Enzymol.”,  1986 , Vol. 121 , p.  210 - 28     (Non-Patent Document  13 ) Massimo YS et al., “J. Immunol. Methods”,  1997 , Vol. 201 , p. 57 - 66     (Non-Patent Document  14 ) Brennan M et al., “Science 38  ,  1985 , Vol. 229 , p.  81     (Non-Patent Document  15 ) Shalaby MR et al., “J. Exp. Med.”,  1992 , Vol. 175 , p. 217 - 25     (Non-Patent Document  16 ) Holliner P et al., “Proc. Natl. Acad. Sci. USA”,  1993 , Vol. 90 , p.  6444 - 8     (Non-Patent Document  17 ) Ridgway JB et al., “Protein Eng.”,  1996 , Vol. 9 , p.  617 - 21     (Non-Patent Document  18 ) Hammerling U et al., “J. Exp. Med.”,  1968 , Vol. 128 , p. 1461 - 73     (Non-Patent Document  19 ) Kurokawa T et al., “Bio/Technology”,  1989 , Vol. 7 , p.  1   163     (Non-Patent Document  20 ) Link BK et al., “Blood”,  1993 , Vol. 81 , p. 3343     (Non-Patent Document  21 ) Nitta T et al., “Lancet”,  1990 , Vol. 335 , p. 368 - 7   1      (Non-Patent Document  22 ) deLeij L et al., “Foundation Nationale de Transfusion Sanguine, Les Ulis France”,  1990 , p. 249 - 53     (Non-Patent Document  23 ) Le Doussal JM et al., “J. Nucl. Med.”,  1993 , Vol. 34 , p.  1662 - 71     (Non-Patent Document  24 ) Stickney DR et al., “Cancer Res.”,  1991 , Vol. 51 , p. 6650 - 5     (Non-Patent Document  25 ) Weiner LM et al., “Cancer Res.”,  1993 , Vol. 53 , p. 94 - 100     (Non-Patent Document  26 ) Kroesen BJ et al., “Br. J. Cancer”,  1994 , Vol. 70 , p. 652 - 61     (Non-Patent Document  27 ) Weiner GJ et al., “J. Immunol.”,  1994 , Vol. 152 , p. 2385     (Non-Patent Document  28 ) Suresh MR et al., “Proc. Natl. Acad. Sci. USA”,  1986 , Vol. 83 , p. 7989 - 93     (Non-Patent Document  29 ) Milstein C and Cuello AC et al., “Nature”,  1983 , Vol. 305 , p. 537     (Non-Patent Document  30 ) Xiang J et al., “Mol. Immunol.”,  1990 , Vol. 27 , p. 809     (Non-Patent Document  31 ) Bebbington CR et al., “Bio/Technology”,  1992 , Vol. 10 , p.  169     (Non-Patent Document  32 ) Huse WD et al., “Science”,  1989 , Vol.  246 , p. 1275     (Non-Patent Document  33 ) McCafferty J et al., “Nature”,  1990 , Vol. 348 , p. 552     (Non-Patent Document  34 ) Kang AS et al., “Proc. Natl. Acad. Sci. USA”,  1991 , Vol. 88 , p.  4363     
 
       Disclosure of the Invention 
       [0063]    An objective of the present invention is to provide bispecific antibodies that substitute for the effect of functional proteins. More specifically, the present invention aims to provide bispecific antibodies that functionally substitute for ligands of receptors comprising heteroreceptor molecules and bispecific antibodies that functionally substitute for the cofactors which enhance enzymatic reaction. 
         [0064]    Through dedicated research, the present inventors succeeded in separating antibodies that functionally substitute for ligands of a type I interferon receptor which comprises two types of molecules: AR  1 -chain and AR 2 -chain. In other words, for the first time, the present inventors successfully separated bispecific antibodies that can functionally substitute for ligands of heteromolecule-comprising receptors. 
         [0065]    Through dedicated research, the present inventors succeeded in discovering bispecific antibodies that specifically bind to both F.IX/F.IXa and F.X, and substitute for the effect of cofactor F.VIIIa (i.e., a function to promote F.X activation by F.IXa). That is, the present inventors succeeded in producing bispecific antibodies that recognize both an enzyme and its substrate and functionally substitute for cofactors of the enzyme. 
         [0066]    The above-mentioned ligand proteins of heteromolecular receptors and the above-mentioned enzyme cofactors are both functional proteins. Indeed, the present inventors have developed for the first time bispecific antibodies that fimctionally substitute for functional proteins. 
         [0067]    The present invention relates to bispecific antibodies that substitute for functional proteins. More specifically, the present invention relates to bispecific antibodies that have an effect of substituting for the ligand function of heteromolecule-comprising receptors, and bispecific antibodies which functionally substitute for cofactors that enhance enzymatic reactions. More specifically, the present invention provides:
   [ 1 ] A bispecific antibody that substitutes for the effect of a functional protein.   [ 2 ] A bispecific antibody that has an activity of functionally substituting for a ligand of a heteromolecule-comprising receptor.   [ 3 ] The antibody according to [ 2 ], wherein said heteromolecule-comprising receptor is a dimer.   [ 4 ] The antibody according to [ 2 ], wherein said receptor is a cytokine receptor.   [ 5 ] The antibody according to [ 4 ], wherein said cytokine receptor is an interferon receptor.   [ 6 ] The antibody according to [ 5 ], wherein said interferon receptor is a type I interferon receptor.   [ 7 ] The antibody according to [ 6 ], wherein said type I interferon receptor comprises an ARI chain and an AR 2  chain.   [ 8 ] The antibody according to [ 7 ], wherein said antibody functionally substitutes for an interferon which is a ligand of a type I interferon receptor.   [ 9 ] The antibody according to [ 8 ], wherein said antibody comprises the variable region of an anti-ARI chain antibody and the variable region of an anti-AR 2  chain antibody.   [ 10 ] The antibody according to [ 9 ], wherein said antibody comprises an anti-ARI chain antibody variable region comprising the amino acid sequence of (a) below and an anti-AR 2  chain antibody variable region comprising the amino acid sequence of any of the following (bl) to (b 10 ):   (a) the H chain variable region amino acid sequence described in SEQ ID NO:  1  and the L chain variable region amino acid sequence described in SEQ ID NO: 2 ;   (b 1 ) the H chain variable region amino acid sequence described in SEQ ID NO:  7  and the L chain variable region amino acid sequence described in SEQ ID NO:  8 ;   (b 2 ) the H chain variable region amino acid sequence described in SEQ ID NO:  9  and the L chain variable region amino acid sequence described in SEQ ID NO:  10 ;   (b 3 ) the H chain variable region amino acid sequence described in SEQ ID NO:  19  and the L chain variable region amino acid sequence described in SEQ ID NO:  20 ;   (b 4 ) the H chain variable region amino acid sequence described in SEQ ID NO:  13  and the L chain variable region amino acid sequence described in SEQ ID NO:  14 ;   (b 5 ) the H chain variable region amino acid sequence described in SEQ ID NO:  23  and the L chain variable region amino acid sequence described in SEQ ID NO:  24 ;   (b 6 ) the H chain variable region amino acid sequence described in SEQ ID NO:  5  and the L chain variable region amino acid sequence described in SEQ ID NO:  6 ;   (b 7 ) the H chain variable region amino acid sequence described in SEQ ID NO:  17  and the L chain variable region amino acid sequence described in SEQ ID NO:  18 ;   (b 8 ) the H chain variable region amino acid sequence described in SEQ ID NO:  15  and the L chain variable region amino acid sequence described in SEQ ID NO:  16 ;   (b 9 ) the H chain variable region amino acid sequence described in SEQ ID NO:  21  and the L chain variable region amino acid sequence described in SEQ ID NO:  22 ;   (b 10 ) the H chain variable region amino acid sequence described in SEQ ID NO: Il and the L chain variable region amino acid sequence described in SEQ ID NO:  12 .   [ 11 ] The antibody according to [ 9 ], wherein said antibody comprises an anti-ARI chain antibody variable region comprising the amino acid sequence of (a) below or an anti-AR 2  chain antibody variable region comprising the amino acid sequence of any of the following (b 1 l) to (b 3 ):   (a) the H chain variable region amino acid sequence described in SEQ ID NO:  3  and the L chain variable region amino acid sequence described in SEQ ID NO:  4 ;   (b 1 ) the H chain variable region amino acid sequence described in SEQ ID NO:  25  and the L chain variable region amino acid sequence described in SEQ ID NO:  26 ;   (b 2 ) the H chain variable region amino acid sequence described in SEQ ID NO:  9  and the L chain variable region amino acid sequence described in SEQ ID NO:  10 ;   (b 3 ) the H chain variable region amino acid sequence described in SEQ ID NO:  21  and the L chain variable region amino acid sequence described in SEQ ID NO:  22 .   [ 12 ] A composition comprising the antibody according to any one of [ 2 ] to [ 11 ] and a pharmaceutically acceptable carrier.   [ 13 ] The composition according to [ 12 ], wherein said composition is a pharmaceutical composition used for preventing and/or treating viral disease, malignant neoplasm, or immune disease.   [ 14 ] The composition according to [ 13 ], wherein said viral disease is a disease that arises and/or progresses as a result of hepatitis C virus infection.   [ 15 ] The composition according to [ 14 ], wherein the disease that arises and/or progresses as a result of hepatitis C virus infection is acute or chronic hepatitis C, cirrhosis, or liver cancer.   [ 16 ] The composition according to [ 13 ], wherein said viral disease is a disease that arises and/or progresses as a result of hepatitis B virus infection.   [ 17 ] The composition according to [ 16 ], wherein the disease that arises and/or progresses as a result of hepatitis B virus infection is acute or chronic hepatitis B, cirrhosis, or liver cancer.   [ 18 ] The composition according to [ 13 ], wherein the malignant neoplasm is chronic myelocytic leukemia, malignant melanoma, multiple myeloma, renal cancer, gliosarcoma, medulloblastoma, astrocytoma, hairy cell leukemia, AIDS-related Kaposi&#39;s sarcoma, skin T lymphoma, or non- Hodgkin&#39;s lymphoma.   [ 19 ] The composition according to [ 13 ], wherein the immune disease is multiple sclerosis.   [ 20 ] A method for preventing and/or treating viral disease, malignant neoplasm, or immune disease, comprising the step of administering the antibody according to any one of [ 2 ] to [ 11 ], or the composition according to any one of [ 12 ] to [ 19 ].   [ 21 ] Use of the antibody according to any one of [ 2 ] to [ 11 ] for producing the composition according to any one of [ 12 ] to [ 19 ].   [ 22 ] A kit used in the method of preventing and/or treating diseases according to [ 20 ], wherein said kit comprises at least the antibody according to any one of [ 2 ] to [ 11 ], or the composition according to [ 12 ].   [ 23 ] An antibody recognizing both an enzyme and a substrate thereof, wherein said antibody is a bispecific antibody which functionally substitutes for a cofactor that enhances the enzymatic reaction.   [ 24 ] The antibody according to [ 23 ], wherein said enzyme is a proteolytic enzyme.   [ 25 ] The antibody according to [ 24 ], wherein said proteolytic enzyme, substrate, and cofactor are blood coagulation/fibrinolysis associated factors.   [ 26 ] The antibody according to [ 25 ], wherein the enzyme of a blood coagulation/fibrinolysis associated factor is blood coagulation factor IX and/or activated blood coagulation factor IX; the substrate is blood coagulation factor X; and the cofactor is blood coagulation factor VIII and/or activated blood coagulation factor VIII.   [ 27 ] The antibody according to any one of [ 23 ] to [ 26 ], wherein said antibody comprises a complementarity determining region comprising the amino acid sequence of anti-blood coagulation factor IX/IXa antibody CDR 3  of the following (a I) or (a 2 ) or a complementarity determining region functionally equivalent thereto, and a complementarity determining region comprising the amino acid sequence of anti-blood coagulation factor X antibody CDR 3  described in any one of the following (bl) to (b 9 ) or a complementarity determining region functionally equivalent thereto: (al) H chain CDR 3  amino acid sequence described in SEQ ID NO:  42 ; (a 2 ) H chain CDR 3  amino acid sequence described in SEQ ID NO:  46 ; (bl) H chain CDR 3  amino acid sequence described in SEQ ID NO:  50 ; (b 2 ) H chain CDR 3  amino acid sequence described in SEQ ID NO:  54 ; (b 3 ) H chain CDR 3  amino acid sequence described in SEQ ID NO:  58 ; (b 4 ) H chain CDR 3  amino acid sequence described in SEQ ID NO:  62 ; (b 5 ) H chain CDR 3  amino acid sequence described in SEQ ID NO:  66 ; (b 6 ) H chain CDR 3  amino acid sequence described in SEQ ID NO:  70 ; (b 7 ) H chain CDR 3  amino acid sequence described in SEQ ID NO:  74 ; (b 8 ) H chain CDR 3  amino acid sequence described in SEQ ID NO:  78 ; (b 9 ) H chain CDR 3  amino acid sequence described in SEQ ID NO:  82 . [ 28 ] The antibody according to any one of [ 23 ] to [ 26 ], wherein said antibody comprises a complementarity determining region comprising the amino acid sequences of anti-blood coagulation factor IX/IXa antibody CDR of the following (al) or (a 2 ) or a complementarity determining region functionally equivalent thereto, and a complementarity determining region comprising the amino acid sequence of anti-blood coagulation factor X antibody CDR described in any one of the following (b I) to (b 9 ) or a complementarity determining region functionally equivalent thereto: (al) H chain CDR  1 ,  2 , and  3  amino acid sequences described in SEQ ID NOs:  40 ,  41 , and  42 , respectively; (a 2 ) H chain CDR  1 ,  2 , and  3  amino acid sequences described in SEQ ID NOs:  44 ,  45 , and  46 , respectively; (bl) H chain CDR  1 ,  2 , and  3  amino acid sequences described in SEQ ID NOs:  48 ,  49 , and  50 , respectively; (b 2 ) H chain CDR  1 ,  2 , and  3  amino acid sequences described in SEQ ID NOs:  52 ,  53 , and  54 , respectively; (b 3 ) H chain CDR  1 ,  2 , and  3  amino acid sequences described in SEQ ID NOs:  56 ,  57 , and  58 , respectively; (b 4 ) H chain CDR  1 ,  2 , and  3  amino acid sequences described in SEQ ID NOs:  60 ,  61 , and  62 , respectively; (b 5 ) H chain CDR  1 ,  2 , and  3  amino acid sequences described in SEQ ID NOs:  64 ,  65 , and  66 , respectively; (b 6 ) H chain CDR  1 ,  2 , and  3  amino acid sequences described in SEQ ID NOs:  68 ,  69 , and  70 , respectively; (b 7 ) H chain CDR  1 ,  2 , and  3  amino acid sequences described in SEQ ID NOs:  72 ,  73 , and  74 , respectively; (b 8 ) H chain CDR  1 ,  2 , and  3  amino acid sequences described in SEQ ID NOs:  76 ,  77 , and  78 , respectively; (b 9 ) H chain CDR  1 ,  2 , and  3  amino acid sequences described in SEQ ID NOs:  80 ,  81 , and  82 ; respectively. [ 29 ] A composition comprising the antibody according to any one of [ 23 ] to [ 28 ] and a pharmaceutically acceptable carrier. [ 30 ] The composition according to [ 29 ], wherein said composition is a pharmaceutical composition used for preventing and/or treating bleeding, disorder accompanied by bleeding, or disorder caused by bleeding. [ 31 ] The composition according to [ 30 ], wherein the bleeding, disorder accompanied by bleeding, or disorder caused by bleeding is a disorder that arises and/or progresses as a result of an activity decrease or deficiency of blood coagulation factor VIII and/or activated blood coagulation factor VIII. [ 32 ] The composition according to [ 31 ], wherein the disorder that arises and/or progresses as a result of an activity decrease or deficiency of blood coagulation factor VIII and/or activated blood coagulation factor VIII is hemophilia A. [ 33 ] The composition according to [ 31 ], wherein the disorder that arises and/or progresses as a result of an activity decrease or deficiency of blood coagulation factor VIII and/or activated blood coagulation factor VIII is a disorder in which an inhibitor against blood coagulation factor VIII and/or activated blood coagulation factor VIII is generated. [ 34 ] The composition according to [ 31 ], wherein the disorder that arises and/or progresses as a result of an activity decrease or deficiency of blood coagulation factor VIII and/or activated blood coagulation factor VIII is acquired hemophilia. [ 35 ] The composition according to [ 31 ], wherein the disorder that arises and/or progresses as a result of an activity decrease of blood coagulation factor VIII and/or activated blood coagulation factor VIII is von Willerbrand&#39;s disease. [ 36 ] A method for preventing and/or treating bleeding, disorder accompanied by bleeding, or disorder caused by bleeding, wherein said method comprises the step of administering the antibody according to any one of [ 23 ] to [ 28 ], or the composition according to any one of [ 29 ] to [ 35 ]. [ 37 ] Use of the antibody according to any one of [ 23 ] to [ 28 ] for preparing the composition according to any one of [ 29 ] to [ 35 ]. [ 38 ] A kit used in the method of preventing and/or treating disorders according to [ 36 ], wherein said kit comprises at least the antibody according to any one of [ 23 ] to [ 28 ] or the composition according to [ 29 ].   
 
         [0110]    A bispecific antibody according to the present invention is a molecule comprising two types of antibodies or antibody fragments having specificities for different antigens. The bispecific antibody is not particularly limited, but preferably monoclonal. 
         [0111]    The bispecific antibodies of the present invention are preferably recombinant antibodies generated using gene recombination techniques (see e.g. Borrebaeck CAK and Larrick JW, THERAPEUTIC MONOCLONAL ANTIBODIES, Published in the United Kingdom by MACMILLAN PUBLISHERS LTD,  1990 ). A recombinant antibody can be obtained by cloning an antibody-encoding DNA from antibody-producing cells, such as hybridomas or sensitized lymphocytes, incorporating the DNA into an appropriate vector, and introducing the vector into a host for antibody production. 
         [0112]    Further, antibodies of the present invention may be antibody fragments or modified antibodies. Antibody fragments may include diabody (Db), linear antibody, single-strand antibody (hereinafter also referred to as scFv) molecules, etc. Herein, “Fv” fragment represents the smallest antibody fragment, comprising a complete antigen-recognizing site and binding site. An “Fv” fragment is a dimer (VH-VL dimer) in which one heavy (H) chain variable region (VH) and one light (L) chain variable region (VL) are strongly connected by a non-covalent bond. Three complementarity determining region (CDRs) of each variable region interact to form an antigen-binding site on the surface of a VH-VL dimer. Six CDRs confer an antigen-binding site on an antibody. However, even one variable region (or half of an Fv, which contains only three antigen specific CDRs) is capable of recognizing an antigen and binding thereto, although its affmity is lower than that of the entire binding site. 
         [0113]    In addition, Fab fragment (also referred to as (F(ab)) further contains an L chain constant region and an H chain constant region (CH 1 ). A Fab fragment differs from a Fab fragment in that the former contains several additional residues derived from the carboxyl terminal of an H chain CH 1  region, which comprises one or more cysteines from the hinge region of an antibody. Fab-SH refers to Fab having a free thiol group in one or more cysteine residues of the constant region. F(ab) fragments are generated by cleaving the disulfide bond in the cysteines of the hinge portion of an F(ab) 2  pepsin digest. Other chemically bound antibody fragments are also known to those skilled in the art. 
         [0114]    Diabody refers to a bivalent antibody fragment constructed by gene fusion (Holliger P et al., Proc. Natl. Acad. Sci. USA  90 :  6444 - 6448  ( 1993 ); EP  404 , 097 ; WO  93 / 11161 ; etc.). Diabody is a dimer comprising two peptide chains; in each polypeptide chain, an L chain variable region (VL) is connected to an H chain variable region (VH) on the same chain via a linker that is too short to allow paring between the two regions (for example, about  5  residues). VL and VH encoded on the same polypeptide chain form a dimer because they cannot form a single-stranded variable region fragment due to the short linker between them. Thus, a diabody ends up with two antigen binding sites. 
         [0115]    A single-strand antibody or scFv fragment contains the VH and VL regions of an antibody, and these regions exist in a single polypeptide chain. In general, an Fv polypeptide further contains a polypeptide linker between VH and VL regions, such that scFv-is able to form a structure that is necessary for antigen binding (see Pluckthun “The Pharmacology of Monoclonal Antibodies” Vol.  113  (Rosenburg and Moore ed (Springer Verlag, New York) pp.  269 - 315 ,  1994  for general remarks on scFv). The linkers of the present invention are not particularly limited, as long as they do not inhibit expression of the antibody variable regions connected to both ends of a linker. 
         [0116]    An IgG type bispecific antibody can be secreted by a hybrid hybridoma (quadroma) formed by fusing two types of hybridomas that produce IgG antibodies (Milstein C et al., Nature  1983 ,  305 :  537 - 540 ). It can also be secreted by introducing into cells genes of the L chains and H chains that constitute the two IgGs of interest (a total of four types of genes) for co-expression. In this case, by appropriately substituting amino acid(s) in the CH 3  region of an H chain, it is possible to preferentially secrete IgGs that have a heterologous combination of H chains (Ridgway, JB et al. Protein Engineering  1996 ,  9 :  617 - 621 , Merchant, AM et al. Nature Biotechnology  1998 ,  16 :  677 - 681 ). 
         [0117]    A bispecific antibody can also be prepared by chemically cross-linking Fab&#39;s. A bispecific F(ab) 2  can be produced, for example, by maleimidating a Fab prepared from one antibody with o-PDM (ortho-phenylenedi-maleimide) and reacting the product with a Fab prepared from another antibody, so as to cross-link Fab&#39;s derived from different antibodies (Keler T et al. Cancer Research  1997 ,  57 :  4008 - 4014 ). Further, a method for chemically connecting antibody fragments such as a Fab-thionitrobenzoic acid (TNB) derivative and Fab thiol (SH) is also known (Brennan M et al. Science  1985 ,  229 :  81 - 83 ). 
         [0118]    Instead of cross linkage, a leucine zipper derived from Fos and Jun or the like can be used. Although Fos and Jun also form a homodimer, their preferential heterodimer formation is utilized. A Fab added with a Fos leucine zipper and a second Fab added with a Jun leucine zipper is expressed for preparation. By mixing and reacting monomeric Fab-Fos and Fab-Jun, which have been reduced under mild conditions, a bispecific F(ab) 2  can be formed (Kostelny SA et al. J. of Immunology,  1992 ,  148 :  1547 - 53 ). This method is not limited to Fab and can also be applied to scFv, Fv, etc. 
         [0119]    A bispecific antibody can also be prepared in a form of diabody. A bispecific diabody is a heterodimer comprising two crossover scFv fragments. That is, a bispecific diabody can be prepared by constructing a heterodimer using VH(A)-VL(B) and VH(B)-VL(A), which have been formed by connecting VH and VL derived from two types of antibodies: A and B, with a relatively short linker of about  5  amino acid residues (Holliger P et al. Proc. of the National Academy of Sciences of the USA  1993 ,  90 :  6444 - 6448 ). 
         [0120]    In this case, construction of a bispecific diabody of interest can be promoted by performing appropriate amino acid substitutions (knobs-into-holes: Zhu Z et al. Protein Science.  1997 ,  6 :  781 - 788 ) so as to link two types of scFv&#39;s with a flexible and relatively long linker of about  15  amino acid residues (a single-chain diabody: Kipriyanov SM et al. J. of Molecular Biology.  1999 ,  293 :  41 - 56 ). sc(Fv) 2  which can be prepared by linking two types of scFv&#39;s with a flexible and relatively long linker of about  15  amino acid residues can also become a bispecific antibody (Mallender WD et al. J. of Biological Chemistry,  1994 ,  269 :  199 - 206 ). 
         [0121]    A modified antibody may be, for example, an antibody that binds to various molecules such as polyethylene glycol (PEG). In the modified antibodies of the present invention, substances to be bound are not limited. Such modified antibodies can be obtained by chemically modifying the antibodies obtained. These methods have already been established in this field. 
         [0122]    The antibodies of the present invention include human antibody, mouse antibody, rat antibody and such, without any limitation on their origins, and may be genetically modified antibodies such as chimera antibody and humanized antibody. 
         [0123]    Methods for obtaining human antibodies are known, and a human antibody of interest can be obtained, for example, by immunizing a transgenic animal having all repertoires of human antibody genes with an antigen of interest (see WO  93 / 12227 , WO  92 / 03918 , WO  94 / 02602 , WO  94 / 25585 , WO  96 / 34096 , WO  96 / 33735 ). 
         [0124]    Genetically modified antibodies can be produced by known methods. Specifically, for example, a chimera antibody comprises variable regions from the H and L chains of an antibody from immunized animals, and constant regions from the H and L chains of a human antibody. A chimera antibody can be obtained by linking a DNA encoding the variable region of an antibody derived from immunized animals with a DNA encoding the constant region of a human antibody, inserting the resulting DNA into an expression vector, and introducing the recombinant vector into a host for production. 
         [0125]    A humanized antibody is a modified antibody also referred to as reshaped human antibody. A humanized antibody is constructed by grafting the complementarity determining region (CDR) of an antibody derived from immunized animals into the CDR of a human antibody. General genetic engineering technologies are also known. 
         [0126]    Specifically, a DNA sequence designed to link the CDR of a mouse antibody to the framework region (FR) of a human antibody is synthesized by PCR, using several oligonucleotides that have been prepared to contain overlapping portions at their terminal regions. After linking the obtained DNA to a DNA encoding the constant region of a human antibody, the resulting DNA is incorporated into an expression vector and introduced into a host to produce a humanized antibody (see EP  239400  and WO  96 / 02576 ). As a human antibody FR to be linked via CDR, one that is capable of forming an antigen-binding site with a good complementarity determining region is selected. Amino acids of the framework region in an antibody variable region may be substituted as necessary, so that the complementarity determining region of a reshaped human antibody forms an appropriate antigen-binding site (Sato K et al, Cancer Research  1993 ,  53 :  851 - 856 ). The framework region may be substituted with framework regions derived from various human antibodies (see WO  99 / 51743 ). 
         [0127]    The present invention provides bispecific antibodies that functionally substitute for fimctional proteins, more preferably, bispecific antibodies that fimctionally substitute for functional proteins. A preferred embodiment of the antibodies of the present invention is an antibody that has an activity to functionally substitute for heteromolecule-comprising receptors. 
         [0128]    In the present invention, heteromolecule-comprising receptors refer to receptors (multimer) composed of two or more different proteins (receptor molecules). Multimers are not limited by the number of proteins (receptor molecules) and include dimers, trimers, tetramers, etc., but are preferably dimers. For example, in the case of a dimer receptor, a heteroreceptor indicates that the two constitutional proteins (receptor molecule) are not identical. 
         [0129]    Antibodies having an activity to finctionally substitute for ligands refer to antibodies that have an agonistic action against certain receptors. In general, when a ligand (i.e., an agonist) binds to a receptor, the tertiary structure of the receptor protein changes and the receptor is activated (in the case of a membrane protein receptor, cell proliferation signals and such are usually emitted). When the receptor type is one that forms a dimer, antibodies that functionally substitute for the ligand can work similarly to a ligand by dimerizing the receptor at an appropriate distance and angle. In other words, anti-receptor antibodies can mimic ligand- induced dimerization of receptors, and become antibodies that functionally substitute for ligands. 
         [0130]    In a preferred embodiment of the present invention, the receptor of the present invention is a cytokine heteroreceptor. 
         [0131]    The term “cytokine” is normally used as a collective term to refer to bioactive proteins that regulate the proliferation and differentiation of various types of hemocytes. It is also used to refer to growth factors and growth inhibitory factors of cells including non-immune cells. Therefore, the term “cytokine” collectively refers to cell-released proteinaceous factors that mediate cell-cell interactions such as regulation of immunoreaction and inflammatory response, antiviral actions, antitumor actions, and regulation of cell proliferation and/or differentiation. 
         [0132]    Specific examples of cytokines that act on heteroreceptors of the present invention include IL- 2 ,  3 ,  4 ,  5 ,  6 ,  7 ,  9 ,  10 ,  11 ,  12 ,  13 , and  15 , colony-stimulating factors (GM-CSF, etc.), interferons (IFN-o:, IFN-P, IFN-y, etc.), CNTF, LIF, Oncostatin M, CT- 1 , and such, but are preferably interferons, especially type I interferons. 
         [0133]    Interferons include IFN-a, IFN-,, IFN-y, IFN-t, etc. IFN-a and IFN-P are highly homologous and thus, these two IFNs can react via a same receptor. Furthermore, IFN-a:, IFN-P, and IFN-r are classified as type I interferon. 
         [0134]    Examples of type I interferon receptors include receptors having an ARI chain (GenBank ACCESSION No: J 03171 , literature: Uze G et al. Cell  1990 ,  60 :  225 - 34 ) and an AR 2  chain (GenBank ACCESSION No: U 29584 , literature: Domanski P et al. J of Biological Chemistry  1995 ,  270 :  21606 - 11 , LutfaUa G et al. EMBO J  1995 ,  14 :  5100 - 8 ). 
         [0135]    The method for obtaining bispecific antibodies that functionally substitute for ligands of the present invention are not particularly limited, and may be obtained by any method. For example, to obtain a bispecific antibody that functionally substitutes for a ligand of a heteroreceptor comprising two types of receptor molecules (A chain and B chain), anti-A chain antibody and anti-B chain antibody are first obtained. Subsequently, a bispecific antibody comprising the H chain and L chain of the anti-A chain antibody, and the H chain and L chain of anti-B chain antibody is produced. Preferably, multiple types of anti-A chain antibodies and anti-B chain antibodies are obtained to produce as many combinations of bispecific antibodies as possible. Bispecific antibodies are produced, and then those that have an activity to functionally substitute for ligands are selected. Bispecific antibodies may be produced by known methods such as fusion of antibody-producing hybridomas, or introduction of antibody expressing vectors into cells. 
         [0136]    Antibodies against receptors may be obtained by methods known to a person skilled in the art. For example, antibodies may be prepared by immunizing immune animals with antigens. Antigens that are used for animal immunization include complete antigens having immunogenicity, and incomplete antigens lacking immunogenicity (including haptens). In the present invention, a receptor whose ligand is functionally substituted by an antibody of the present invention presumed to act as the ligand is used as an antigen (immunogen) mentioned above. The above-mentioned receptor of the present invention is not particularly limited, but is preferably a heterodimer. For example, mice, hamsters, or rhesus monkeys may be used as an immune animal. These animals may be immunized with antigens by a person skilled in the art, using well known methods. In the present invention, variable regions of the L chain and H chain are preferably recovered from immunized animals, or cells of the animals. This process may be carried out by methods generally known to a person skilled in the art. Animals immunized with an antigen express antibodies against the antigen, especially in their spleen cells. For example, mRNAs may be prepared from spleen cells of the immunized animals, and the L chain and H chain variable regions may be recovered by RT-PCR using primers that correspond to the variable region of the animal. 
         [0137]    Specifically, the A chain and B chain are each used to immunize an animal. Receptors used as the immunogen may be a whole protein constituting a receptor, or a partial peptide of the protein. Further, the immunogen used for animal immunization may be made into a soluble immunogen by binding an antigenic molecule, or fragments thereof, with other molecules. When transmembrane molecules, such as receptors, are used as an antigen, it is preferable to use their fragments (for example, extracellular region of a receptor). Cells expressing a transmembrane molecule on their cell surface may also be used as an antigen. Such cells may be naturally occurring cells (tumor cell lines etc.) or cells constituted by genetic recombination techniques to express transmembrane molecules. mRNAs are extracted from spleen cells of an immunized animal, and cDNAs of the L chain and H chain variable regions are recovered by RT-PCR using primers corresponding to regions in the vicinity of the variable regions. Primers corresponding to CDR, primers corresponding to framework regions which are less diversified than CDR, or primers corresponding to signal sequences and CHI or L chain constant region (CL) may also be used. Lymphocytes may be immunized in vitro and used to construct scFv- or Fab-presenting libraries. Clones of antigen-bound antibodies are concentrated by panning and cloned, and antibody expression vectors are produced using their variable regions. Anti-A chain antibody expression vector and anti-B chain antibody expression vector are introduced into a same cell, and by expressing the antibodies, a bispecific antibody is obtained. In this case, screening may be performed using similar MRNA libraries derived from human peripheral blood mononuclear cells, spleen, tonsil and such, or those of unimmunized animals. 
         [0138]    Antibodies that have an activity to functionally substitute for ligands may be selected, for example, by the following methods. ( 1 ) Add an antibody to a culture of cells that proliferate in a ligand-dependent manner, check whether or not the cells proliferate as in the case of ligand addition, and use it as an indicator. If the cells proliferate, the subject multispecific antibody is judged to have an effect of functionally substituting for the ligand. ( 2 ) Add an antibody to the culture of a cell line that reflects the original activity of a ligand (but not necessarily proliferation), check whether or not the cells react to the added antibody the same way as to the ligand and use it as an indicator. If the cells react the same way as how they react to the ligand, the antibody is judged to have an effect of functionally substituting for the ligand. 
         [0139]    The above cells normally express on their cell surface heteroreceptors against which antibodies can act as agonists, and the receptors bind to ligands to emit signals. Cells used in the above method are preferably cells that can proliferate dependently on receptor ligands (ligand-dependent proliferating cells). Normally, the above receptors are preferably those that emit cell proliferation signals by binding to a ligand. However, if the above receptor is one that does not emit cell proliferation signals, the receptor can be fused with a type of receptor that emits cell proliferation signals to form a so-called chimeric receptor, for use in the above methods. The chimeric receptor emits cell proliferation signals by binding with a ligand. Receptors that are suitable for the construction of chimeric receptors by fusing with a receptor are not particularly limited as long as they are a type of receptor that emits cell proliferation signals. They are normally membrane proteins, and preferably, receptors comprising a receptor fragment with a ligand-binding function (extracellular region), and a receptor fragment with a signal transduction function (intracellular region). Receptors used for the intracellular region are specifically GH receptor, G-CSF receptor, MPL, EPO receptor, c-Kit, Flt- 3  IL- 2  receptor, IL- 3  receptor, IL- 5  receptor, GM-CSF receptor and such. Specifically, suitable examples of the above ligand-dependent dependent proliferating cells of the present invention include, ligand-dependent proliferating cell Ba/F 3 , which expresses chimeric receptors in which the extracellular region is a ligand receptor fragment and the intracellular region is a G-CSF receptor fragment. Examples of cells that can be used in the above methods include, for example, NFS 60 , FDC-Pl, FDC-P 2 , CTLL- 2 , DA- 1 , and KT- 3 . 
         [0140]    The antibodies thus obtained may be purified to homogeneity. Separation and purification of antibodies may be performed by separation and purification methods used for general proteins. Without being limited thereto, antibodies can be separated and purified by, for example, arbitrarily selecting and combining chromatography columns such as affinity chromatography, filters, ultrafiltration, salt precipitation, dialysis, SDS polyacrylamide gel electrophoresis, and isoelectric focusing (Antibodies: A Laboratory Manual. Ed Harlow and David Lane, Cold Spring Harbor Laboratory,  1988 ). Columns used for affinity chromatography include protein A column, protein G column and such. 
         [0141]    When the antibody of the present invention is, for example, an antibody that has an effect of functionally substituting for a ligand of a type I interferon receptor comprising an ARl chain and an AR 2  chain, the antibody preferably has a structure comprising the variable region of an anti-ARlchain antibody and the variable region of an anti-AR 2  chain antibody. An antibody that functionally substitutes for interferon was produced by the following method. IL- 3  dependent mouse proB cell line Ba/F 3 , which expresses a chimeric receptor comprising the intracellular region of G-CSF receptor and the extracellular region of either of the receptor molecules (ARl chain and AR 2  chain) of the type I interferon receptor, was established. BALB/c was intraperitoneally immunized with either of the cells. 
         [0142]    PolyA(+)RNA was extracted from the spleen of an immunized mouse with an elevated antibody titer, scFv was synthesized by RT-PCR, and an scFv presenting phage library was constructed. After mixing a phage library derived from the spleen of an ARl chain-expressing Ba/F 3  immunized mouse and biotinylated soluble ARl chain, bound phages were concentrated by a panning method, which captures the phages by streptavidin magnetic beads. Phages presenting the anti-ARI chain antibody were selected by ELISA using soluble ARI chain. Similarly, anti-AR 2  chain antibody phages were selected using soluble AR 2  chain and library phages derived from the spleen of an AR 2  chain-expressing Ba/F 3  immunized mouse. Antibodies comprising a different amino acid sequence for the H chain CDR 3 , which is thought to be most involved in antibody specificity, were selected. 
         [0143]    An scFv-CHl-Fc expression vector was produced by inserting scFv between a signal sequence for animal cells and CHI -hinge-CH 2 -CH 3 . Anti-ARI chain antibodies and anti-AR 2  chain antibodies were introduced into cells in various combinations for the expression of bispecific antibodies. 
         [0144]    BaF 3 -ARG was established by introducing into Ba/F 3 , expression vectors of chimeric molecules comprising the extracellular region of ARI chain or AR 2  chain and the intracellular region of G-CSF receptor. These cells proliferated IFN-A dependently. Bispecific antibodies comprising an antibody combination that could support BaF 3 -ARG proliferation were selected. 
         [0145]    Daudi cells are a human B-cell line that is highly sensitive to cell growth inhibition activity by IFN-x. The earlier selected bispecific antibodies were added to Daudi cells and confirmed to inhibit proliferation like IFN-x. The antibodies are not particularly limited and include, for example, antibodies comprising either of the following anti-ARI chain antibody variable regions, or one of the following anti-AR 2  chain antibody variable regions. -Variable regions of anti-ARI chain antibody: AR 1 - 41 , AR 1 - 24  -Variable regions of anti-AR 2  chain antibody: AR 2 - 37 , AR 2 - 1   1 , AR 2 - 13 , AR 2 - 45 , AR 2 - 22 , AR 2 - 43 , AR 2 - 40 , AR 2 - 14 , AR 2 - 44 , AR 2 - 33 , and AR 2 - 31  Amino acid sequences of the VH and VL for each of the above-mentioned variable regions are shown in SEQ ID NOs:  1  to  26  (correlation between the variable regions VH and VL and the SEQ ID NOs: is shown in Table  1  below). 
         [0000]    
       
         
               
               
               
             
               
               
               
               
             
               
               
               
               
             
           
               
                   
                 TABLE 1 
               
             
             
               
                   
                   
               
               
                   
                 SEQ ID NO: 
                   
               
             
          
           
               
                   
                 Variable region 
                 V H   
                 V L   
               
               
                   
                   
               
             
          
           
               
                   
                 AR1-41 
                 1 
                 2 
               
               
                   
                 AR1-24 
                 3 
                 4 
               
               
                   
                 AR2-37 
                 5 
                 6 
               
               
                   
                 AR2-11 
                 7 
                 8 
               
               
                   
                 AR2-13 
                 9 
                 10 
               
               
                   
                 AR2-45 
                 11 
                 12 
               
               
                   
                 AR2-22 
                 13 
                 14 
               
               
                   
                 AR2-43 
                 15 
                 16 
               
               
                   
                 AR2-40 
                 17 
                 18 
               
               
                   
                 AR2-14 
                 19 
                 20 
               
               
                   
                 AR2-44 
                 21 
                 22 
               
               
                   
                 AR2-33 
                 23 
                 24 
               
               
                   
                 AR2-31 
                 25 
                 26 
               
               
                   
                   
               
             
          
         
       
     
         [0146]    When the anti-ARl chain antibody is ARl- 24 , its partner anti-AR 2  chain antibody is preferably AR 2 - 13 , AR 2 - 31 , or AR 2 - 44 , and when the anti-ARI chain antibody is ARl- 41 , its partner anti-AR 2  chain antibody is preferably AR 2 - 1   1 , AR 2 - 13 , AR 2 - 14 , AR 2 - 22 , AR 2 - 33 , AR 2 - 37 , AR 2 - 40 , AR 2 - 43 , AR 2 - 44 , or AR 2 - 45 . AR 2 - 13  and AR 2 - 44  can become a partner for both AR 1 - 41  and AR 1 - 24  antibodies. The present invention also includes antibodies that form pairs as shown above. 
         [0147]    A preferred embodiment of a bispecific antibody that functionally substitutes for a fuictional protein of the present invention is a bispecific antibody that functionally substitutes for a cofactor that recognizes both an enzyme and its substrate. 
         [0148]    Cofactors of the present invention are not particularly limited, as long as they are capable of acting on an enzyme to enhance the enzymatic reaction. A cofactor of the present invention is, for example, a cofactor of a proteolytic enzyme. Specific examples of a cofactor of a proteolytic enzyme are cofactors for blood coagulation and fibrinolysis associated factors (F.VIII/F.VIIIa, PZ, TM, TM/PS system), cofactors for complement reactions (C 4 b, MCP, CR 1 , H factor), and such. 
         [0149]    The following combinations can be listed as specific examples of enzyme and enzyme substrate, as well as enzyme cofactors. (a) Cofactor for blood coagulation and fibrinolysis associated factor (Example  1 ) 
         [0000]    
       
         
               
               
               
             
           
               
                   
                   
               
             
             
               
                   
                 Enzyme: 
                 F.IXa 
               
               
                   
                 Substrate: 
                 F.X 
               
               
                   
                 Cofactor: 
                 F.VIII/F.VIIIa 
               
               
                   
                   
               
             
          
         
       
     
         [0150]    Cofactor F.VIIIa binds to both F.IXa and F.X and enhances F.X activation by F.IXa. Among bispecific antibodies that recognize both the above-described enzyme F.IXa and substrate F.X, some have an enhancing effect on F.X activation. Some of these antibodies are thought to have an effect of substituting for the function of cofactor F.VIII/F.VIIIa. (b) Cofactor for blood coagulation and fibrinolysis associated factor (Example  2 ) 
         [0000]    
       
         
               
               
               
             
           
               
                   
                   
               
             
             
               
                   
                 Enzyme: 
                 ZPI 
               
               
                   
                 Substrate: 
                 F.X/F.Xa 
               
               
                   
                 Cofactor: 
                 PZ 
               
               
                   
                   
               
             
          
         
       
     
         [0151]    Cofactor PZ binds to ZPI of the serpin family and F.Xa to enhance the F.Xa-inhibiting activity of ZPI. Specifically, some bispecific antibodies that recognize both ZPI and F.X/F.Xa are thought to have an effect of substituting for the PZ function. (c) Cofactor for blood coagulation and fibrinolysis associated factor (Example  3 ) 
         [0000]    
       
         
               
               
               
             
           
               
                   
                   
               
             
             
               
                   
                 Enzyme: 
                 thrombin 
               
               
                   
                 Substrate: 
                 TAFI 
               
               
                   
                 Cofactor: 
                 TM 
               
               
                   
                   
               
             
          
         
       
     
         [0152]    Cofactor TM enhances TAFI activation by thrombin. Specifically, some bispecific antibodies that recognize both thrombin and TAFI are thought to have an effect of substituting for the TM function. (d) Cofactors for blood coagulation and fibrinolysis associated factor (Example  4 ) 
         [0000]    
       
         
               
               
               
             
           
               
                   
                   
               
             
             
               
                   
                 Enzyme: 
                 thrombin 
               
               
                   
                 Substrate: 
                 PC 
               
               
                   
                 Cofactors: 
                 TM/PS 
               
               
                   
                   
               
             
          
         
       
     
         [0153]    The TM/PS system enhances PC activation by thrombin. Specifically, some bispecific antibodies that recognize both thrombin and PC are thought to functionally substitute for the TM/PS system. (e) Cofactor for complement reactions (Example  1 ) 
         [0000]    
       
         
               
               
               
             
           
               
                   
                   
               
             
             
               
                   
                 Enzyme: 
                 C1s 
               
               
                   
                 Substrate: 
                 C2 
               
               
                   
                 Cofactor: 
                 C4b 
               
               
                   
                   
               
             
          
         
       
     
         [0154]    C 4 b has CIs promoting effect on C 2  decomposition. That is, among the bispecific antibodies that recognize both CIs and C 3 , some are thought to functionally substitute for C 4 b. (f) Cofactors for complement reactions (Example  2 ) 
         [0000]    
       
         
               
               
               
             
           
               
                   
                   
               
             
             
               
                   
                 Enzyme: 
                 Complement Regulatory Factor I 
               
               
                   
                 Substrate: 
                 C3b 
               
               
                   
                 Cofactors: 
                 Complement Regulatory Factor H, 
               
               
                   
                   
                 Membrane Cofactor Protein (MCP), and 
               
               
                   
                   
                 Complement Receptor 1 (CR1) 
               
               
                   
                   
               
             
          
         
       
     
         [0155]    Complement Regulatory Factors H, MCP, and CR 1  have the promoting effect of Complement Regulatory Factor  1  on C 3 b degradation. Specifically, among bispecific antibodies that recognize both Complement Regulatory Factor  1  and C 3 b, some are thought to functionally substitute for Complement Regulatory Factors H, MCP, and CR 1 . 
         [0156]    Among the above-described cofactors, F.VIII/F.VIIIa is particularly preferable. Although F.VIII/F.VIIIa undergoes limited proteolysis by proteolytic enzymes such as thrombin, as long as it has F.VIII/F.VIIIa activity, its form does not matter. Further, F.VIII/F.VIIa variants and F.VIII/F.VIIIa that have been artificially modified by gene recombination techniques are also included in F.VIII/F.VIIIa, as long as they retain F.VIII/F.VIIIa cofactor activity. 
         [0157]    Methods for obtaining bispecific antibodies which functionally substitute for cofactors of the present invention are not particularly limited, and may be obtained by any methods. For example, when obtaining a bispecific antibody that functionally substitutes for enzyme A and substrate B, enzyme A and substrate B are each immunized to an animal to obtain anti-enzyme A antibody and anti-substrate B antibody. Subsequently, a bispecific antibody comprising the anti- enzyme A antibody H and L chains and the anti-substrate B antibody H and L chains is produced. Herein, it is desirable to obtain several types of each of the anti-enzyme A antibody and the anti- substrate B antibody, such that these antibodies can be preferably used to produce as many combinations of bispecific antibodies as possible. After bispecific antibodies are produced, antibodies with an activity that substitutes for cofactor fluction are selected. 
         [0158]    Antibodies against an enzyme or a substrate can be obtained by methods known to those skilled in the art. For example, antibodies can be prepared by immunizing animals with antigens. Antigens for immunizing animals are, for example, complete antigens having immunogenicity and incomplete antigens (including hapten) without immunogenicity. In the present invention, an enzyme whose cofactor can be fuictionally substituted by an antibody of the present invention which acts as the cofactor, or a substrate of the enzyme, is used as the above-described antigen (immunogen). As animals to be immunized, for example, mouse, hamster, or rhesus monkey can be used. Immunization of these animals with antigens can be performed by methods known to those skilled in the art. In the present invention, antibody L chain and H chain variable regions are preferably collected from immunized animals or cells thereof. This procedure can be performed by one skilled in the art by using generally known methods. Antigen-immunized animals express antibodies against the antigen, especially in the spleen cells. Therefore, for example, MRNA can be prepared from spleen cells of an immunized animal, and variable regions of the L chain and H chain can be recovered by RT-PCR using primers to the animal&#39; 861  variable regions. 
         [0159]    Specifically, animals are immunized with an enzyme or a substrate. The enzyme and substrate used as immunogens may be whole proteins or partial peptides thereof. Further, depending on the circumstances, a candidate antigen bound to another molecule to form a soluble antigen, or fragments of which, may be used as an immunogen for immunizing animals. 
         [0160]    MRNA is extracted from the spleen cells of immunized animals, and cDNAs of the L chain and H chain variable regions are recovered by RT-PCR, using primers to the vicinity of the variable regions. Primers to CDR, primers to framework regions which are less diversified than CDR, or primers to signal sequences and CHI or L chain constant region (CL) may also be used. Further, lymphocytes can also be immunized in vitro, and used to construct scFv or Fab presenting libraries. Antigen-binding antibody clones are concentrated and cloned by panning, and their variable regions are used to produce antibody expression vectors. By introducing an anti-enzyme antibody expression vector and an anti-substrate antibody expression vector into a same cell and expressing the antibodies, a bispecific antibody can be obtained. In this case, screening can also be performed using similar libraries constructed from mRNAs derived from the peripheral blood monocytes, spleen, tonsil and such of human and non-immunized animals as materials. 
         [0161]    Antibodies that have a cofactor function-substituting activity can be selected, for example, by the methods described below. ( 1 ) In a reaction system comprising the enzyme and the substrate, the selection is performed using elevation of enzyme activity (substrate degradation ability) as an index, wherein the elevation of enzyme activity is a result of antibody addition. ( 2 ) In a system for measuring or simulating the biological functions which the enzyme, substrate, and cofactor are involved in (for example, a system for measuring plasma coagulation), the selection is performed using activity of functional recovery as an index, wherein the activity of functional recovery is a result of antibody addition in the absence of the cofactor. 
         [0162]    The antibody thus obtained can be purified to homogeneity. Separation and purification of the antibody may be performed by separation and purification methods used for general proteins. For example, antibodies can be separated and purified by appropriately selecting and combining chromatography columns such as affmity chromatography, filter, ultrafiltration, salting out, dialysis, SDS polyacrylamide gel electrophoresis, isoelectric electrophoresis and so on (Antibodies: A Laboratory Manual. Ed Harlow and David Lane, Cold Spring Harbor Laboratory,  1988 ), but the methods are not limited thereto. A column used in affinity chromatography is, for example, protein A column, protein G column and such. 
         [0163]    For example, when F.VIII/F.VIIIa is the substitute cofactor, that is, when the enzyme and substrate combination is plasma coagulation and fibrinolysis associated factors F.IXa and F.X, the bispecific antibody of the present invention preferably has a structure comprising the variable region of an anti-F.IXa antibody and the variable region of an anti-F.X antibody. 
         [0164]    Bispecific antibodies of the present invention which functionally substitute for F.VIII/F.VIIIa were generated by the following method. Mice were subcutaneously immunized with commercial F.IXa or F.X. Spleen cells were isolated from spleens of the immunized mice with an elevated antibody titer, and fused with mouse myeloma cells to form hybridomas. Hybridomas that bind to antigen F.IXa or F.X were selected, and the L chain and H chain variable regions were recovered by RT-PCR, using primers to the variable regions. The L chain variable region was incorporated into a CL-containing L chain expression vector, and the H chain variable region was inserted into an H chain expression vector containing an H chain constant region. 
         [0165]    The anti-F.IXa antibody (H chain, L chain) expression vectors and anti-F.X antibody (H chain, L chain) expression vectors were introduced into same cells for antibody expression and bispecific antibodies were obtained. 
         [0166]    Bispecific antibodies thus obtained were assessed for their effects to functionally substitute for F.VIII/F.VIIIa (cofactors for F.X activation by F.IXa) in an assay system comprising F.XIa (F.IX activating enzyme), F.IX (F.X activating enzyme), F.X, a synthetic substrate (S- 2222 ) for F.Xa, and phospholipid. Given this result, bispecific antibodies having the activity to substitute for F.VIII/F.VIIIa were selected. 
         [0167]    The bispecific antibodies selected above were measured for their ability to restore coagulation in a coagulation assay system (APTT) that uses human F.VIII-deficient plasma. The results confirmed that bispecific antibodies which have the ability to restore coagulation in human F.VIII-deficient plasma were obtained. 
         [0168]    The H chain CDR 3 s of the present invention&#39;s antibodies are not particularly limited, but specifically have a complementarity determining region comprising either the amino acid sequence of the XB  12  H chain CDR 3  sequence (SEQ ID NO:  42 ) or the XT 04  H chain CDR 3  sequence (SEQ ID NO:  46 ) described below in the examples, or those fimctionally equivalent thereto, and the complementarity determining region comprising an amino acid sequence described in any one of the H chain CDR 3  sequences (SEQ ID NOs:  50 ,  54 ,  58 ,  62 ,  66 ,  70 ,  74 ,  78 , and  82 ) in SB 04 , SBO 5 , SBO 6 , SBO 7 , SB 21 , SB 30 , SB 34 , SB 38 , and SB 42 , respectively, or those functionally equivalent thereto. 
         [0169]    Further, a specific example of the above-described antibodies is preferably combined from an antibody having a complementarity determining region comprising either an H chain CDR sequence of XB 12  (SEQ ID NOs:  40 - 42 ) or an H chain CDR sequence of XT 04  (SEQ ID NOs:  44 - 46 ), or a complementarity determining region functionally equivalent thereto, and an antibody having a complementarity determining region comprising any one of the H chain CDR sequences (SEQ ID NOs:  48 - 50 ,  52 - 54 ,  56 - 58 ,  60 - 62 ,  64 - 66 ,  68 - 70 ,  72 - 74 ,  76 - 78 , or  80 - 82 ) in SB 04 , SB 05 , SB 06 , SB 07 , SB 21 , SB 30 , SB 34 , SB 38 , and SB 42 , respectively, or a complementarity determining region functionally equivalent thereto. 
         [0170]    The amino acid sequences of the H chain variable regions of XB 12 , XT 04 , SB 04 , SB 05 , SB 06 , SB 07 , SB 21 , SB 30 , SB 34 , SB 38 , and SB 42  disclosed in the present invention are shown as SEQ ID NOs:  39 ,  43 ,  47 ,  51 ,  55 ,  59 ,  63 ,  67 ,  71 ,  75 , and  79 . 
         [0171]    When preparing a full-length antibody using the variable regions disclosed in the present invention, the constant regions are not particularly limited, and those known to one skilled in the art, for example, constant regions described in “Sequences of proteins of immunological interest, ( 1991 ), U.S. Department of Health and Human Services. Public Health Service National Institutes of Health” and “An efficient route to human bispecific IgG, ( 1998 ). Nature Biotechnology vol.  16 ,  677 - 681 ”, and such can be used. 
         [0172]    In one embodiment of the antibodies of the present invention, the antibody of the present invention is expected to, through its ligand function-substituting effect, become an effective drug against diseases caused by a decrease in the activity (function) of the receptor on which the antibody acts. 
         [0173]    When the ligand for which the antibody of the present invention functionally substitutes is IFN-a/p, the above diseases include, for example, viral diseases, malignant neoplasms, and immune diseases. 
         [0174]    Viral diseases include, for example, diseases that arise and/or progress via hepatitis C virus, and more specifically, acute hepatitis C, chronic hepatitis C, cirrhosis, liver cancer and such. 
         [0175]    Chronic hepatitis C is a chronic inflammatory disease caused by host immune response against hepatitis C virus-infected cells. As the symptoms progress, liver function gradually decreases and through cirrhosis, leads to liver cancer at the end. In order to eliminate hepatitis C virus from chronic hepatitis C patients, interferon-a/p therapy is carried out. However, due to their short half life in blood, daily administration is required and thus places a considerably heavy burden on the patient. Therefore, drugs which have the interferon-a/p effect and an outstanding sustainability are in demand. 
         [0176]    Other examples of viral diseases include diseases that arise and/or progress via hepatitis B virus, and more specifically, acute hepatitis B, chronic hepatitis B, cirrhosis, liver cancer and such. 
         [0177]    Examples of malignant neoplasms include chronic myelocytic leukemia, malignant melanoma, multiple myeloma, renal cancer, gliosarcoma, medulloblastoma, astrocytoma, hairy cell leukemia, AIDS related Kaposi&#39;s sarcoma, skin T lymphoma, and non Hodgkin&#39;s lymphoma. 
         [0178]    An example of an immune disease is multiple sclerosis. 
         [0179]    In other embodiments, the antibodies of the present invention have an effect to functionally substitute for cofactors, and are thus expected to become effective drugs for diseases caused by decrease in the activity (function) of these cofactors. In cases where the cofactor functionally substituted by an antibody of the present invention is a blood coagulation and fibrinolysis-associated factor, the above-described diseases are, for example, bleeding, diseases accompanied by bleeding, diseases caused by bleeding, and such. In particular, functional reduction and deficiency in F.VIII/F.VIIIa, F.IX/F.IXa, and F.XI/F.XIa have been known to cause abnormal hemorrhage referred to as hemophilia. 
         [0180]    Of the hemophilias, abnormal hemorrhage due to congenital hypofunction of F.VIIIIF.VIIIa or deficiency in F.VIII/F.VIIIa is referred to as hemophilia A. When hemophilia A patient bleeds, replacement therapy with a F.VIII formulation is performed. In addition, preventive administration of a F.VIII formulation may be performed (see Non-Patent Documents  2  and  3 ) on the day of vigorous exercise or on field trip, when frequent intra-articular bleeding occurs, or when the patient is classified as severe hemophilia. Since this preventive administration of F.VIII formulation remarkably reduces hemorrhage episodes of patients with hemophilia A, it has recently become widely popular. Reduction of bleeding episodes not only reduces lethal and nonlethal bleeding risks and the accompanying agony, but also prevents hemophilic arthropathy caused by frequent intra-articular hemorrhage. As a result, it greatly contributes to the improvement of hemophilia A patients QOL. 
         [0181]    The half life of a F.VIII formulation in blood stream is as short as about  12  to  16  hours. Therefore, for continuous prevention, it is necessary to administer an F.VIII formulation about three times a week. This is equivalent to maintaining approximately  1 % F.VIII activity or more (see Non-Patent Documents  4  and  5 ). Also, in replacement therapies for bleeding event, it is necessary to periodically administer booster F.VIII formulations for a certain period of time, except when the bleeding is mild, in order to prevent rebleeding and establish complete hemostasis. 
         [0182]    Further, F.VIII formulations are intravenously administered. There are technical difficulties in performing intravenous administration, and it becomes even more difficult particularly when performing administration on young patients whose veins are thin. 
         [0183]    In the above-described preventive administration of F.VIII formulation and emergency administration thereof in cases of bleeding event, home treatment and self-injection are used in most cases. The need for frequent administration and the technical difficulties involved not only inflict pain on patients, but also become a reason that hinders home treatment and self-injection from becoming popular. 
         [0184]    Accordingly, there have been strong demands for, as compared to current blood coagulation Factor VIII formulations, drugs that have longer administration intervals and drugs that can be easily administered. 
         [0185]    Further, anti-F.VIII antibodies which are referred to as inhibitors may be generated in hemophilia A patients, particularly in severe hemophilia A patients. If an inhibitor is generated, effects of F.VIII formulation become hindered by the inhibitor. As a result, hemostasis control becomes very difficult for patients. 
         [0186]    When such hemophilia A inhibitor patient bleeds, neutralization therapy using a mass dose of F.VIII formulation, or bypass therapy using a complex concentrate or F.VIIa formulation is usually.performed. However, in neutralization therapy, administration of a mass dose of F.VIII formulation may adversely enhance the inhibitor (anti-F.VIII antibody) titer. Additionally, in bypass therapy, the relatively short half-lives (about  2  to  8  hours) of complex concentrates and the F.VIIa formulation are becoming problematic. Furthermore, since their action mechanisms are independent of the F.VIII/F.VIIIa function, that is, a function to catalyze the activation of F.X by F.IXa, hemostatic mechanism may not function well and become nonresponsive. Therefore, in many cases of hemophilia A inhibitor patients, sufficient hemostatic effects are not obtained when compared to hemophilia A non-inhibitor patients,. 
         [0187]    Therefore, there have been strong demands for drugs that are unaffected by the presence of inhibitors and which can functionally substitute for F.VIII/F.VIIIa. 
         [0188]    In addition to hemophilia and acquired hemophilia caused by anti-F.VIII autoantibody, von Willebrand&#39;s disease, which is caused by functional abnormality or deficiency of vWF, has been known as an abnormal bleeding disorder associated with F.VIII/F.VIIIa. vWF is necessary not only for the normal adhesion of platelets to subendothelial tissues at sites of vessel wall damage, but also for the formation of complexes with F.VIII to maintain a normal plasma F.VIII level. In patients with von Willebrand&#39;s disease, these functions decline and functional abnormality of hemostasis occurs. 
         [0189]    In the above-described respects, methods that utilize antibodies may be considered for creation of drugs that (i) have long administration intervals, (ii) are easily administered and (iii) are unaffected by the presence of inhibitors, and (iv) can functionally substitute for F.VIII/F.VIIIa in a F.VIII/F.VlIla-independent manner. Generally, the half-lives of antibodies in blood stream are relatively long from several days to several weeks. Further, antibodies are known to migrate into the blood stream after subcutaneous administration. That is, antibody drugs meet the above-described requirements of (i) and (ii). 
         [0190]    Other embodiments of the present invention&#39;s functional proteins include proteins that control multiple different physiological functions by binding to two types of proteins having different physiological functions. Suitable examples include C 4 b binding protein (C 4 bp) which binds to fourth component of complement (C 4 b) and protein S (PS). C 4 bp not only dissociates C 2 b from the C 4 b-C 2 b complex, but also acts to eliminate the aPC cofactor activity of PS. Therefore, C 4 bp shows regulatory effects towards the complement system and blood coagulation system. Bispecific antibodies against C 4 b and PS are thought to have an effect of substituting for the C 4 bp function. Further, C 4 bp acts as a cofactor in C 4 b decomposition by the I Factor. Therefore, bispecific antibodies against the I Factor and C 4 b are also considered to have an effect of substituting for the C 4 bp function. 
         [0191]    The present invention provides pharmaceutical compositions comprising an antibody of the present invention as an active ingredient. For example, when an antibody of the present invention is an antibody that has an activity of functionally substituting for interferons against cytokine receptors, the antibody is thought to have cytokine-mimetic effects. Therefore, the antibody is expected to become a pharmaceutical (pharmaceutical composition) or drug with an antiviral effect, antitumor effect, and cell growth and/or differentiation regulating effect. On the other hand, an antibody that functionally substitutes for IL- 2  is expected to become a pharmaceutical (pharmaceutical composition) or drug with adjuvanticity and/or an anti-tumor effect by differentiation and/or activation of T cells or NK cells; an antibody that functionally substitutes for IL- 3  is expected to become a pharmaceutical (pharmaceutical composition) or drug with an effect of promoting hemocyte recovery by proliferation of hemopoietic precursor cells; an antibody that functionally substitutes for IL- 4  is expected to become a pharmaceutical (pharmaceutical composition) or drug with an anti-allergic effect by Th 2  induction (humoral immunity); an antibody that functionally substitutes for IL- 5  is expected to become a pharmaceutical (pharmaceutical composition) or drug with adjuvanticity and/or an anti-tumor effect by B cell induction and/or eosinophil proliferation and/or differentiation; an antibody that functionally substitutes for IL- 6  is expected to become a pharmaceutical (pharmaceutical composition) or drug with an effect of stimulating platelet production; an antibody that functionally substitutes for IL- 7  is expected to become a pharmaceutical (pharmaceutical composition) or drug with adjuvanticity and/or an anti-tumor effect by proliferation of T cells and/or B cells; an antibody that functionally substitutes for IL- 9  is expected to become a pharmaceutical (pharmaceutical composition) or drug with an effect of promoting hemocyte recovery by proliferation and/or hematopoiesis of mast cells; an antibody that functionally substitutes for IL- 10  is expected to become a pharmaceutical (pharmaceutical composition) or drug with an immunosuppressive effect; an antibody that functionally substitutes for IL-II is expected to become a pharmaceutical (pharmaceutical composition) or drug with an effect of stimulating platelet production; an antibody that functionally substitutes for IL- 12  is expected to become a pharmaceutical (pharmaceutical composition) or drug with adjuvanticity and/or an anti-tumor effect by ThI induction (cellular immunity); an antibody that functionally substitutes for IL- 1   5  is expected to become a pharmaceutical (pharmaceutical composition) or drug with adjuvanticity and/or an anti-tumor effect by the activation of NK cells; an antibody that functionally substitutes for GM-CSF is expected to become a pharmaceutical (pharmaceutical composition) or drug with an effect of promoting leukocyte recovery after chemotherapy or bone marrow transplantation; an antibody that functionally substitutes for CNTF is expected to become a pharmaceutical (pharmaceutical composition) or drug with an anti-obesity effect; an antibody that functionally substitutes for LIF is expected to become a pharmaceutical (pharmaceutical composition) or drug with an effect of stimulating platelet production and/or an effect of decreasing blood cholesterol; an antibody that functionally substitutes for Oncostatin M is expected to become a pharmaceutical (pharmaceutical composition) or drug with a hematopoiesis accelerating effect; and an antibody that functionally substitutes for CT-I is expected to become a pharmaceutical (pharmaceutical composition) or drug with a cardiac muscle protective effect. 
         [0192]    Further, when the antibody of the present invention is one of the antibodies that recognize both F.IX or F.IXa and F.X, and can functionally substitute for F.VIIIa, the antibody is expected to become a pharmaceutical (pharmaceutical composition) or drug for preventing or treating bleeding, disorders accompanied by bleeding, or disorders caused by bleeding. 
         [0193]    At the same time, it is expected that an antibody that binds to ZPI and F.X and fluctionally substitutes for PZ becomes a pharmaceutical (pharmaceutical composition) or drug with anti-thrombotic action; an antibody that binds to thrombin and TAFI and functionally substitutes for TM becomes a pharmaceutical (pharmaceutical composition) or drug with hemostasis-promoting action; and a pharmaceutical (pharmaceutical composition) or drug that binds to thrombin and PC and has an effect of functionally substituting for PS/TM system. 
         [0194]    In addition, since complement C 4  deficiency causes systemic lupus erythematosus (SLE), an antibody that fuictionally substitutes for C 4 b is expected to become a pharmaceutical (pharmaceutical composition) or drug with an effect that suppresses SLE occurrence. Since H factor deficiency causes suppurative infection and autoimmune glomerulonephritis, an antibody that functionally substitutes for H factor is expected to become a pharmaceutical (pharmaceutical composition) or drug with an effect of suppressing the onset of these diseases. 
         [0195]    Since C 4 bp deficiency causes Behcet&#39;s disease, an antibody that substitutes for the C 4 bp fuinction is expected to become a pharmaceutical (pharmaceutical composition) or drug with an effect of suppressing the onset of Behcet&#39;s disease. 
         [0196]    For formulation of pharmaceuticals, pharmaceutical compositions comprising an antibody of the present invention used for treatment or prevention as an active ingredient may be mixed with an appropriate pharmaceutically acceptable carrier, medium and such that are inert thereto, if needed. For example, sterile water or physiological saline, stabilizer, excipient, antioxidant (ascorbic acid etc.), buffer (phosphoric acid, citric acid, other organic acids, etc.), antiseptic, surfactant (PEG, Tween, etc.), chelating agent (EDTA, etc.), binding agent and such can be cited. Pharmaceutical compositions may also contain other low molecular weight polypeptides, proteins such as serum albumin, gelatin, and immunoglobulin, amino acids such as glycine, glutamine, asparagine, arginine, and lysine, sugars such as polysaccharide and monosaccharide and carbohydrates, and sugar alcohols such as mannitol and sorbitol. When preparing aqueous solutions for injection, for example, solubilizing agents include physiological saline, isotonic solutions containing glucose and other adjunctive agents such as D-sorbitol, D- mannose, D-mannitol, and sodium chloride, and may be used in combination with appropriate solubilizing agents such as alcohol (ethanol etc.), polyalcohol (propylene glycol, PEG etc.), and non-ionic surfactant (polysorbate  80 , HCO- 50  etc.). 
         [0197]    Further, if necessary, antibodies of the present invention may be encapsulated into microcapsules (microcapsules made of hydroxymethyl cellulose, gelatin, poly(methyl methacrylate), etc.), or included in a colloidal drug delivery system (liposome, albumin microsphere, microemulsion, nanoparticle, and nanocapsule, etc.) (see “Remington&#39;s Pharmaceutical Science  16 th edition”, Oslo Ed. ( 1980 ) etc.). Methods for formulating sustained- release drugs are also known, and can be applied to antibodies of the present invention (Langer et al., J.Biomed.Mater.Res.  15 :  267 - 277  ( 1981 ); Langer, Chemtech.  12 :  98 - 105  ( 1982 ); U.S. Patent No:  3 , 773 , 919 ; European Patent Application No (EP):  58 , 481 ; Sidman et al., Biopolymers  22 :  547 - 556  ( 1983 ); EP 133 , 988 ). 
         [0198]    Although the dosage of the pharmaceutical compositions of the present invention is appropriately determined considering the type of formulation, method of administration, age and body weight of patients, symptoms of patients, type and progress of disease, etc, and ultimately by doctors, generally, doses of  0 . 1 - 2000  mg/day can be divided into one to several oral administrations for adults. The dosage is preferably  1  to  1000  mg/day, more preferably  5  to  500  mg/day, and most preferably  100  to  300  mg/day. Although the dosage varies according to the body weight and age of patients, administration methods and such, one skilled in the art can suitably select an appropriate dosage. Preferably, the dosing period is also appropriately determined according to, for example, the healing process of patients. 
         [0199]    Further, it is also possible to perform gene therapy by inserting a gene encoding an antibody of the present invention into gene therapy vectors. As an administration method apart from direct administration of naked plasmids, the genes may be administered by packaging into liposome and such, or insertion into various virus vectors such as retrovirus vectors, adenovirus vectors, vaccinia virus vectors, pox virus vectors, adeno-associated virus vectors, and HVJ vectors (see Adolph “Virus Genome Method” CRC Press, Florid ( 1   996 )), or by coating onto carrier beads such as colloidal gold particle (W 093 / 17706  etc.). However, the gene may be administered by any methods, as long as the antibody can be expressed in vivo to exert its action. Preferably, a sufficient dose is administered through an appropriate parenteral route, such as intravenous, intraperitoneal, subcutaneous, intracutaneous, intra-adipose tissue, intramammary, and-intramuscular injection and infusion, inhalation, gas-inducible particle bombardment method (with an electron gun and such), or mucosal route using nasal drop. Genes encoding an antibody of the present invention may be administered by introducing the gene into blood cells, cells derived from bone marrow and such, using ex vivo liposome transfection, particle bombardment method (U.S. Patent No.  4 , 945 , 050 ) or virus infection, and re-introducing these cells into animals. 
         [0200]    The present invention also provides methods for preventing and/or treating bleeding, disorders accompanied by bleeding, or disorders caused by bleeding, comprising the steps of administering an antibody or composition of this invention. Antibodies or compositions can be administered, for example, by the aforementioned methods. 
         [0201]    The present invention also relates to use of the antibodies of this invention for manufacturing (pharmaceutical) compositions of this invention. 
         [0202]    Further, the present invention provides kits comprising at least an antibody or composition of this invention to be used in the above-described methods. Glass syringe, injection needle, pharmaceutically acceptable medium, alcohol cotton, bandage, instruction manual that describes the usage, or such may also be optionally packaged into the kits. 
     
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         [0203]      FIG. 1  is a drawing showing the insertion site of pcDNA 4 -g 4 H. 
           [0204]      FIG. 2  is a drawing showing the insertion site of pcDNA 4 -g 4 L and pIND-g 4 L. 
           [0205]      FIG. 3  is a drawing showing the insertion site of pIND-g 4 H. 
           [0206]      FIG. 4  shows results of measuring the F.VIIIa-mimetic activity of an anti-F.IXa/anti-F.X bispecific antibody generated from anti-F.IXa antibody XB 12  and anti-F.X antibody SBO 4 , SB 21 , SB 42 , SB 38 , SB 30 , SBO 7 , SBO 5 , SBO 6 , or SB 34 . The concentration of the antibody solutions was  10  jig/mL (final concentration  1  pg/iL). As a result, nine types of bispecific antibodies showed an increase of F.VIIIa-mimetic activity in the order of activity strength: XB 12 /SBO 4 , XB 12 /SB 21 , XB 12 /SB 42 , XBI 2 /SB 38 , XB 12 /SB 30 , XB 12 /SB 07 , XB 12 /SBO 5 , XB  12 /SBO 6 , and XB  12 /SB 34 . 
           [0207]      FIG. 5  shows results of measuring the F.VIIIa-mimetic activity of the XT 04  antibody or an anti-F.IXa/ F.X bispecific antibody generated from anti-F.IXa antibody XT 04  and anti-F.X antibody SBO 4 , SB 21 , SB 42 , SB 38 , SB 30 , SBO 7 , SBO 5 , SBO 6 , or SB 34 . The concentration of the antibody solutions was  10  pg/mL (final concentration  1  pg/mL). As a result, XT 04 /SBO 4 , XT 04 /SB 21 , XT 04 /SB 42 , XT 04 /SB 38 , XT 04 /SB 30 , XT 04 /SBO 7 , XT 04 /SBO 5 , XT 04 /SBO 6 , and XT 04 /SB 34  showed elevated F.VIIIa-mimetic activity. 
           [0208]      FIG. 6  shows results of measuring the F.VIIIa-mimetic activity of various concentrations of XB  12 /SBO 4 , which showed the highest activity in  FIG. 4 . As a result, XB  12 /SBO 4  showed a concentration-dependent increase of F.VIJIa-mimetic activity. 
           [0209]      FIG. 7  shows results of measuring the plasma coagulation time (APTT) in the presence of XB 12 /SBO 4 , XB 12 /SB 21 , XB 12 /SB 42 , XB 12 /SB 38 , XB 12 /SB 30 , XB 12 /SBO 7 , XB 12 /SBO 5 , XB 12 /SBO 6 , or XB 12 /SB 34 . The antibody solution concentration was  20  pg/mL, except for XB 12 /SB 06  which was  3 . 4  pg/mL. As a result, XB 12 /SBO 4 , XB 12 /SB 21 , XB 12 /SB 42 , XB 12 /SB 38 , XB 12 /SB 30 , XB 12 /SBO 7 , XB 12 /SBO 5 , XB 12 /SBO 6 , and XB 12 /SB 34  showed a coagulation time shortening effect compared with in the absence of the antibodies. 
           [0210]      FIG. 8  shows results of measuring the plasma coagulation time (APTT) in the presence of XT 04 /SBO 4 , XT 04 /SB 21 , XT 04 /SB 42 , XT 04 /SB 38 , XT 04 /SB 30 , XT 04 /SB 07 , XT 04 /SBO 5 , XT 04 /SBO 6 , or XT 04 /SB 34 . The antibody solution concentration was  20  pg/mL, except for XT 04 /SBO 6  which was  10  pg/mL. As a result, XT 04 /SBO 4 , XT 04 /SB 2   1 , XT 04 /SB 42 , XT 04 /SB 38 , XT 04 /SB 30 , XT 04 /SBO 7 , XT 04 /SBO 5 , and XT 04 /SBO 6  showed a coagulation time shortening effect compared with in the absence of the antibodies. XT 04 /SB 34  did not show a coagulation time-shortening effect. 
           [0211]      FIG. 9  shows results of measuring the coagulation time with various concentrations of XB 12 /SBO 4 , which showed the highest coagulation time (APTT)-shortening effect in  FIGS. 7 and 8 . As a result, XB  12 /SBO 4  showed a concentration-dependent effect of shortening the coagulation time. 
           [0212]      FIGS. 10 to 13  show the ISRE activation ability of antibodies against pISRE-Luc introduced K 562  cells. o shows IFN-a 2 a and * shows the combination of anti-ARI chain and anti-AR 2  chain bispecific antibodies in each figure. The antibodies are shown to activate ISRE in a dose-dependent manner with a per-molecule specific activity comparable to that of IFN. 
       
    
    
     DETAILED DESCRIPTION  
       [0213]    Herein below, the present invention will be specifically described with reference to Examples, but it is not to be construed as being limited thereto. 
       Example 1  
     Antigen and Immunization 
       [0214]    Expression vectors for a soluble receptor, in which the C terminal of the extracellular region of either human ARI chain or AR 2  chain was tagged with FLAG (ARIFLAG, AR 2 FLAG) or His 6  (ARI His, AR 2 His), were introduced into CHO cells separately and purified from culture supernatants using affmity columns. The expression vector for a chimeric molecule comprising the extracellular region of human ARI chain and the intracellular region of G-CSF receptor was introduced into mouse proB cell line Ba/F 3  to establish a high expression cell line. A high expression cell line was similarly established for a chimeric molecule comprising the extracellular region of human AR 2  chain and the intracellular region of G-CSF receptor. The cells were individually used to intraperitoneally immunize BALB/c. ARI His or AR 2 His was intravenously injected three days before excising the spleen. 
       Example 2   
     Separation of Antibodies Form an scFv Presenting Library 
       [0215]    (a) Panning of Phage Library 
         [0216]    PolyA(+)RNA was extracted from the spleen of an immunized mouse, and scFv was synthesized by RT-PCR to construct a phagemid library expressing scFv as a fusion protein with gene 3  of fl phage (J. Immun. Methods,  201 , ( 1997 ),  35 - 55 ). The E. coli library ( 2  x  10   9  cfu) was inoculated into  50  mL of  2 x YTAG ( 2 x TY containing  100  pg/mL ampicillin and  2 % glucose), and cultured at  37 ° C till OD  600  reached  0 . 4  to  0 . 5 . 4  x  101  ofhelperphage VCSM 13  was added to the culture, which was left to stand at  37 ° C for  15  minutes for infection. The infected cells were cultured at  26 ° C for  10  hours, following addition of  450  niL of  2 x YTAG and  25  jL of  1  mol/L IPTG. The culture supernatant was collected by centrifugation, mixed with  100  mL of PEG-NaCl ( 10 % polyethylene glycol  8000 ,  2 . 5  mol/L NaCI), and left to stand at  4 ° C for  60  minutes. Phage was precipitated by centrifugation at  10 , 800 x g for  30  minutes, and the precipitate was suspended in  40  mL of water, mixed with  8  niL of PEG-NaCi, and left to stand at  4 ° C for  20  minutes. Phage was precipitated by centrifugation at  10 , 800 x g for  30  minutes, and suspended in  5  mL of PBS. ARI FLAG and AR 2 FLAG prepared in Example  1  were labeled with biotin using No-Weigh Premeasured NHS-PEO 4 -Biotin Microtubes (Pierce).  100  pmol of biotin labeled ARIFLAG or AR 2 FLAG was added to the phage library and contacted with the antigen for  60  minutes.  600  jL of Streptavidin MagneSphere (Promega) washed with  5 % M- PBS (PBS containing  5 % skim milk) added for binding for  15  minutes. Beads were washed with I mL PBST (PBS containing  0 . 1  % Tween- 20 ) and PBS three times each. The beads were suspended in  0 . 8  mL of  0 . 1  mol/L glycine/HCI (pH  2 . 2 ) for  5  minutes to elute the phage. The phage solution thus collected was neutralized by adding  2  mol/L Tris ( 45  liL), added to  10  mL of XLl-Blue in logarithmic growth phase (OD  600  = 0 . 4  to  0 . 5 ), and left to stand for  30  minutes at  37 ° C for infection. The mixture was spread on a  2 x YTAG plate and cultured at  30 ° C. Colonies were collected, inoculated into  2 x YTAG, and cultured at  37 ° C until OD  600  = 0 . 4  to  0 . 5 . IPTG ( 1  mol/L;  5  pL) and helper phage VCSM 13  ( 10  pfu) were added to the culture solution ( 10  mL), and the mixture was left to stand at  37 ° C for  30  minutes. The cells were collected by centrifugation, resuspended in  2 x YTAG ( 100  mL) containing kanamycin ( 25  jig/mL), and cultured at  30 ° C for  10  hours. The culture supernatant was collected by centrifugation, mixed with of PEG-NaCI ( 20  nmL), and left to stand at  4 ° C for  20  minutes. Phage was precipitated by centrifugation at  10 , 800 x g for  30  minutes, and suspended in PBS ( 2  mL), and provided for the subsequent panning. Beads were washed five times each for PBST and PBS at the second panning. Clones producing AR chain binding phages were selected by ELISA, from E.coli that could infect the eluted phages. 
         [0000]    (b) Phage ELISA 
         [0217]    The above-described single colony was inoculated into  2 x YTAG ( 150  jL) and cultured at  30 ° C overnight. After  5  lL of this culture was inoculated into  2 x YTAG ( 500  JL) and cultured at  37 ° C for  2  hours, helper phage ( 2 . 5  x  109  pfu) and  2 x YTAG ( 100  JIL) containing  1  mol/L IPTG ( 0 . 3  ,L) was added, and the culture was then left to stand at  37 ° C for  30  minutes. After subsequent overnight culture at  30 ° C, the centrifuged supernatant was subjected to ELISA. StreptaWell  96  microtiter plate (Roche) was coated over night with PBS ( 100  [L) containing  1 . 0  gg/mL biotin-labeled ARIFLAG or AR 2 FLAG. After washing with PBST to remove the antigen, the reaction was blocked with  200  lL of  2 % (w/v) M-PBS over night. After removal of  2 % (w/v) M-PBS, the culture supernatant was added therein and left to stand for  40  minutes for antibody binding. After washing, the bound phage was detected with an HRP-bound anti-M 13  antibody (Amersham Pharmacia Biotech) diluted with  2 % (w/v) M-PBS, and BM blue POD substrate (Roche). The reaction was stopped by adding sulfuric acid, and the A 450  value was measured. 
         [0000]    (c) Sequence Determination and Clone Selection 
         [0218]    The scFv region was amplified by PCR using primers PBG 3 -FI ( 5 -CAGCTATGAAATACCTATTGCC - 3 /SEQ ID NO:  27 ) and PBG 3 -Rl ( 5 -CTTTTCATAATCAAAATCACCGG- 3 /SEQ ID NO:  28 ) from the phage solution of an ELISA positive clone, and its nucleotide sequence was determined. A PCR reaction solution ( 20  lL) containing  1  lL phage solution,  2  pL  10  x KOD Dash buffer solution,  10  Fmol/L primer ( 0 . 5  jL each), and  0 . 3  lL KOD Dash polymerase (TOYOBO,  2 . 5  U/PL) was amplified on a Perkin Elmer  9700  via  30  cycles of  96 ° C.,  10  seconds,  55 ° C,  10  seconds, and  72 ° C,  30  seconds. After PCR,  3  lL of ExoSAP-IT (Amersham) was added to  5  lL of the reaction solution, and incubated at  37 ° C for  20  minutes, then at  80 ° C for  15  minutes. This sample was reacted with primer PBG 3 -F 2  ( 5 -ATTGCCTACGGCAGCCGCT - 3 /SEQ ID NO: 29 ) or PBG 3 -R 2  ( 5 ′-AAATCACCGGAACCAGAGCC - 3 ′/SEQ ID NO: 30 ) using a BigDye Terminator Cycle Sequencing kit (Applied Biosystems), and electrophoresed on an Applied Biosystems PRISM  3700  DNA Sequencer. For each of the anti-ARI chain and anti-AR 2  chain,  45  clones with CDR 3  amino acid sequences different from those predicted from the nucleotide sequences were selected. 
       Example 3  
     Expression of Bispecific Antibodies 
       [0219]    For expression as scFv-CH 1 -Fc, an expression vector pCAGGss-g 4 CH hetero IgG 4 , where scFv can be inserted between a human signal sequence (driven by promoter CAGG) and the intron -CHl-Fc (human IgG 4  cDNA) via an SfiI site, was constructed. For expression as a heteromolecule, amino acid substitutes that are substituted at the CH 3  site of IgG 4  were produced based on the knobs-into-holes of IgGl (Ridgway JB et al. Protein Engineering  1996 ,  9 :  617 - 621 ). Type A is a substitute with Y 349 C and T 366 W substitutions, and type B is a substitute with E 356 C, T 366 S, L 368 A, and Y 407 V substitutions. The substitution of -ppcpScp- to -ppcpPcp- was introduced into the hinge region of both types. Type A was constructed with a human IL- 3  signal sequence (pCAGG-IL 3 ss-g 4 CHPa) and type B with a human IL- 6  signal sequence (pCAGG-IL 6 ss-g 4 CHPb). PCR products of the scFv region of the clones selected based on the nucleotide sequences were SfiI treated, then the anti-ARl chain clone was subdloned into pCAGG-IL 3 ss-g 4 CHPa and the anti-AR 2  chain clone was subcloned into pCAGG-IL 3 ss-g 4 CHPb. Expression vectors for a total of  2025  combinations (anti-ARI chain and anti-AR 2  chain clones  45  x  45 ) were used to transfect HEK  293  cells using lipofectamine  2000 , and three days later, culture supernatants were collected. 
       Example 4  
     Separation of Ligand Function-Substituting Bispecific Antibodies 
       [0220]    (a) Ba/F 3  Growth Assay 
         [0221]    BaF 3 -ARG was established by introducing expression vectors for chimeric molecules comprising the extracellular region of ARI chain or AR 2  chain and the intracellular region of G- CSF receptor into Ba/F 3  cells, which proliferate in a mouse IL- 3 -dependent manner. BaF 3 -ARG proliferated IFNoc-dependently. After three washes,  0 . 1  ImL medium containing the sample and  1 X 103  cells per well was seeded to a  96 -well plate. After four days of culture,  10  liL of Cell Count Reagent SF (Nacalai Tesque) was added and incubated at  37 ° C for two hours, and then A 450  was measured. 
         [0222]    (b) Daudi Cell Proliferation Inhibition Assay 
         [0223]    Daudi cells are a human B cell line with high sensitivity towards IFN.  6 . 25  x  10   3  cells per well were seeded to a  96 -well plate in  0 . 1  ImL medium containing the sample. After four days of culture,  10  pL of Cell Count Reagent SF (Nacalai Tesque) was added and incubated at  37 ° C for two hours, and then A 450  was measured. 
         [0224]    (c) Sequences of Ligand Function-Substituting Bispecific Antibodies 
         [0225]    Amino acid sequences of the variable regions of the antibodies selected by the above screening method are described as SEQ ID NOs: I to  26 . Correlation between the name of each antibody and the SEQ ID NO is shown in the above Table  1 . 
         [0226]    (d) Reporter Gene Assay Using ISRE 
         [0227]      40  Rg of pISRE-Luc was added to  3  niL of OPTI-MEM I and  100  IL DMRIE-C (Invitrogen), stirred, and left to stand at room temperature for  20  minutes. This was added to  8  x  106  human K 562  cells prepared in  2  mL OPTI-MEM I, and after four hours of culturing at  37 ° C,  10  mL of  15 %FCS-RPMI 1640  was added and the cells were cultured overnight. The next day, K 562  collected by centrifugation was resuspended in  10 . 5  mL of  10 % FCS-RPMI 1640  and seeded to a  96 -well flat bottom plate at  70  ,L/well. 
         [0228]    Bispecific scFv-CH in the culture supernatants of HEK 293  cells introduced with the antibody gene was adjusted to a concentration of  12 . 5  ng/mL with reference to IgG and a series of  5 -fold dilutions were made. Alternatively, culture supernatants of COS 7  cells expressing bispecific IgG were diluted  2 -fold and a series of  5 -fold dilutions were made. These were added to cells introduced with a reporter plasmid at  30  EL/well. For the positive control wells, a series of  5 -fold dilutions of IFN-a  2 a were dispensed at  30  EL/well. After culturing at  37 ° C for  24  hours,  50  lL/mL of a Bright-Glo Luciferase Assay System (Promega) was added and left to stand at room temperature for  10  minutes, and luciferase activity was determined with Analyst HT (LJL) ( FIG. 10 ,  FIG. 1 ,  FIG. 12 , and  FIG. 13 ). 
       Example 5  
     Preparation of Non-Neutralizing Antibody Against Factor IXa (F.IXa) 
       [0229]      5 - 1 . Immunization and preparation of hybridomas Eight BALB/c mice (male,  6  weeks old when immunization was initiated (Charles River, Japan)) and five MRL/lpr mice (male,  6  weeks old when immunization was initiated (Charles River, Japan)) were immunized with Factor IXap (Enzyme Research Laboratories, Inc.) as described below. As an initial immunization, Factor IXap ( 40  jg/head) emulsified with FCA (Freund&#39;s complete adjuvant H 37  Ra (Difco laboratories)) was subcutaneously administered. Two weeks later, Factor IXap ( 40  pig/head) emulsified with FIA (Freund&#39;s incomplete adjuvant (Difco laboratories)) was subcutaneously administered. Afterward, three to seven booster immunizations were performed at one week intervals. After the titer of a plasma antibody against Factor IXap was confirmed to be elevated by ELISA (Enzyme linked immunosorbent assay) described in  5 - 2 , Factor IXap ( 40  ig/head) diluted in PBS(-) (phosphate buffered saline free of calcium ion and magnesium ion) was intravenously administered as a fmal immunization. Three days after the final immunization, mice spleen cells were fused with mouse myeloma cells P 3 X 63 Ag 8 U. 1  (referred to as P 3 U 1 , ATCC CRL- 1597 ) by a standard method using PEG 1500  (Roche Diagnostics). Fused cells suspended in RPMI 1640  medium (Invitrogen) containing  10 % FBS (Invitrogen) (hereinafter referred to as  1  o%FBS/kPMI  1640 ) were seeded in a  96 -well culture plate, and  1 ,  2 ,  3 , and  5  days after the fusion, the medium was replaced with a HAT selection medium ( 10 % FBS/RPMI 1   640  /  2 % HAT  50 x concentrate (Dainippon Pharmaceutical Co. Ltd) /  5 % BM-Condimed H 1  (Roche Diagnostics)-to selectively culture hybridomas. Using the supernatants collected on the  8 ,h or  9 th day after fusion, Factor IXa-binding activity was measured by ELISA described in  5 - 2  to select hybridomas having Factor IXa-binding activity. Subsequently, the activity of neutralizing Factor IXa enzymatic activity was measured by the method described in  5 - 3  to select hybridomas that do not have Factor IXa-neutralizing activity. Hybridomas were cloned twice by performing limiting dilutions in which one cell is seeded in each well of a  96 -well culture plate. Single colony cells confimed by microscopic observation were subjected to ELISA and neutralization activity assay as described in  5 - 2  and  5 - 3  was performed for clone selection. Ascites containing the cloned antibody was prepared by the method described in  5 - 4 , and the antibody was purified from the ascites. The purified antibody was unable to extend APTT (activated partial thromboplastin time) and this was confirmed by the method described in  5 - 5 .  5 - 2 . Factor IXa ELISA Factor IXap was diluted to  1  jg/mL with a coating buffer ( 100  mM sodium bicarbonate, pH  9 . 6 ,  0 . 02 % sodium azide) and distributed in Nunc-Immuno plate (Nunc-Immuno  96  MicroWellm plates MaxiSorpm (Nalge Nunc International)) at  100  gL/well. Then, the plate was incubated at  4 ° C overnight. After washing the plate with PBS(-) containing Tween(R)  20  thrice, it was blocked with a diluent buffer ( 50  mM Tris-HCl, pH  8 . 1 ,  1 % bovine serum albumin,  1  mM MgCl 2 ,  0 . 15  M NaCl,  0 . 05 % Tween(R)  20 ,  0 . 02 % sodium azide) at room temperature for  2  hours. After removal of the buffer, a diluent buffer-diluted mouse antiserum or hybridoma culture supernatant was added at  100  ElL/well, and incubated at room temperature for  1  hour. After washing the plate thrice, alkaline phosphatase-labeled goat anti-mouse IgG (H+L) (Zymed Laboratories) which had been diluted to  1 / 2000  with the diluent buffer was added at  100  gL/well, and incubated at room temperature for  1  hour. After washing the plate six times, a colorimetric substrate Blue-Phosm Microwell Phosphatase Substrate (Kirkegaard &amp; Perry Laboratories) was added at  100  gL/well, and incubated at room temperature for  20  minutes. After adding the Blue- Phosm Stop Solution (Kirkegaard &amp; Perry Laboratories) ( 100  gL/well), absorbance at  595  nm was measured with a Model  3550  Microplate Reader (Bio-Rad Laboratories).  5 - 3 . Measurement of Factor IXa neutralizing activity Phospholipid (Sigma-Aldrich) was dissolved in distilled water for injection, and ultrasonicated to prepare a phospholipid solution ( 400  gg/mL). Tris buffered saline containing  0 . 1 % bovine serum albumin (hereinafter abbreviated as TBSB) ( 40  gL),  30  ng/mL Factor IXa, (Enzyme Research Laboratories) ( 10  EL),  400   4 g/mL phospholipid solution ( 5  PL), TBSB containing  100  mM CaCl 2  and  20  mM MgCl 2  ( 5  ,L), and hybridoma culture supernatant ( 10  [L) were mixed in a  96 -well plate, and incubated at room temperature for  1  hour. To this mixed solution,  50  gg/mL Factor X (Enzyme Research Laboratories) ( 20  [L) and  3  U/mL Factor VIII (American diagnostica) ( 10  gL) were added and reacted at room temperature for  30  minutes. The reaction was stopped by adding  0 . 5  M EDTA ( 10  gL). After addition of an S- 2222  solution ( 50  gL; Chromogenix) and incubation at room temperature for  30  minutes, the absorbance was measured at measurement wavelength  405  nm and reference wavelength  655  nm on a Model  3550  Microplate Reader (Bio-Rad Laboratories, Inc.).  5 - 4 . Ascites preparation and antibody purification Ascites of the established hybridomas was produced according to standard procedures. That is, the hybridoma was cultured in vitro ( 2  x  106 ) and transplanted into the peritoneal cavity of a BALB/c mouse (male,  5  to  7  weeks old at the time experiment was started, Japan Charles River) or BALB/c nude mouse (female,  5  to  6  weeks old at the time experiment was started, Japan Charles River and Japan CLEA), which was intraperitoneally administered twice with pristane ( 2 , 6 , 10 , 14 -tetramethylpentadecane, WAKO Pure Chemical Industries) in advance. One to four weeks after the transplantation, ascites was collected from the mouse with an inflated abdomen. 
         [0230]    The antibody was purified from the ascites using a Protein G Sepharosem  4  Fast Flow  5  column (Amersham Biosciences). The ascites was diluted  2 -fold with a binding buffer ( 20  mM sodium acetate, pH  5 . 0 ) and applied to the column, which had been washed with  10  column volumes of the binding buffer. The antibody was eluted with  5  column volumes of an elution buffer ( 0 . 1  M glycine-HCI, pH  2 . 5 ), and neutralized with a neutralizing buffer ( 1  M Tris-HCl, pH  9 . 0 ). The resulting solution was concentrated using a Centriprep Tm    10  (Millipore), and the  10  solvent was replaced with TBS ( 50  mM Tris-buffered saline). The antibody concentration was calculated from the absorbance at  280  nm with A ( 1 %,  1  cm) = 13 . 5 . Absorbance was measured with DU- 650  (Beckman Coulter).  5 - 5 . Measurement of APTT (Activated Partial Thromboplastin Time)  1   5  APTT was measured with a CR-A (Amelung)-connected KC  1 OA (Amelung). A mixture of the TBSB-diluted antibody solution ( 50  jiL), standard human plasma (Dade Behring) ( 50  pL), and APTT reagent (Dade Behring) ( 50  lL) was warmed at  37 ° C for  3  minutes. To this mixture,  20  mM CaCl 2  (Dade Behring) ( 50  [tL) was added to start a coagulation reaction, and the coagulation time was measured.  20   
       Example 6  
     Preparation of Non-Factor X (F.X)-Neutralizing Antibody  6 - 1 . Immunization and Hybridoma Preparation 
       [0231]    Eight BALB/c mice (male,  6  weeks old when immunization was initiated, Japan Charles River) and five MRL/lpr mice (male,  6  weeks old when immunization was initiated, Japan  25  Charles River) were immunized with Factor X (Enzyme Research Laboratories) as described below. As an initial immunization, Factor X ( 40  gg/head) emulsified with FCA was subcutaneously administered. Two weeks later, Factor X ( 20  or  40  gg/head) emulsified with FIA was subcutaneously administered. Subsequently, three to six booster immunizations were given at one week intervals. After the titer of a plasma antibody against Factor X was confirmed  30  to be elevated by ELISA as described in  6 - 2 , Factor X ( 20  or  40  fg/head) diluted in PBS (-) was administered intravenously as a final immunization. Three days after the fmal immunization, mouse spleen cells were fused with mouse myeloma P 3 U 1  cells, according to a standard method using PEG 1500 . Fused cells suspended in  10 % FBS/RPMI 1640  medium were seeded in a  96 - well culture plate, and hybridomas were selectively cultured by replacing the medium with a  35  HAT selection medium  1 ,  2 ,  3  and  5  days after the fusion. Binding activity toward Factor X was measured by ELISA described in  6 - 2 , using the culture supernatant collected on the  8 th day after fusion. Hybridomas having Factor X-binding activity were selected, and their activities to neutralize Factor Xa enzymatic activity were measured by the method described in  6 - 3 . Hybridomas that do not have a neutralizing activity toward Factor Xa were cloned by performing limiting dilution twice. Ascites containing the cloned antibody was prepared by the method described in  5 - 4 , and the antibody was purified from the ascites. The purified antibody was unable to extend APTT and this was confirmed by the method described in  5 - 5 .  6 - 2 . Factor X ELISA Factor X was diluted to  1  jg/iL with a coating buffer, and dispersed into Nunc-Immuno plate at  100  tL/well. Then the plate was incubated at  4 ° C overnight. After washing the plate with PBS (-) containing Tween (R)  20  thrice, it was blocked with a diluent buffer at room temperature for  2  hours. After removal of the buffer, a diluent buffer-diluted mouse antiserum or hybridoma culture supernatant was added to the plate, and incubated at room temperature for  1  hour. After washing the plate thrice, alkaline phosphatase-labeled goat anti-mouse IgG (H+L) which had been diluted to  1 / 2000  with the diluent buffer was added, and incubated at room temperature for  1  hour. After washing the plate six times, a colorimetric substrate Blue-PhosTm Microwell Phosphatase Substrate (Kirkegaard &amp; Perry Laboratories)was added at  100  JAL/well, and incubated at room temperature for  20  minutes. After adding Blue-PhosTm Stop Solution (Kirkegaard &amp; Perry Laboratories) ( 100  EL/well), absorbance at  595  nm was measured with a Model  3550  Microplate Reader (Bio-Rad Laboratories).  6 - 3 . Measurement of Factor Xa-neutralizing activity Hybridoma culture supernatant diluted to  1 / 5  with TBSB ( 10  iL) was mixed with  40  JL of TBCP (TBSB containing  2 . 78  mM CaCI 2  and  22 . 2  ,uM phospholipids (phosphatidyl choline:phosphatidyl serine = 75 : 25 , Sigma-Aldrich) containing  250  pg/mL Factor Xa (Enzyme Research Laboratories), and incubated at room temperature for  1  hour. To this mixed solution, TBCP ( 50  lL) containing prothrombin (Enzyme Research Laboratories) ( 20  jg/mL) and  100  ng/mL activated coagulation factor V (Factor Va (Haematologic Technologies)) were added, and reacted at room temperature for  10  minutes. The reaction was stopped by adding  0 . 5  M EDTA ( 10  liL). To this reaction solution,  1  mM S- 2238  solution (Chromogenix) ( 50  liL) was added, and after incubation at room temperature for  30  minutes, absorbance at  405  nm was measured with a Model  3550  Microplate Reader (Bio-Rad Laboratories). 
       Example 7   
     Construction of Chimera Bispecific Antibody Expression Vector 
       [0232]      7 - 1 . Preparation of Antibody Variable Region-Encoding DNA Fragments from Hybridomas 
         [0233]    From the hybridomas that produce anti-F.IXa antibody or anti-F.X antibody, total RNA was extracted using the QIAGEN(R) RNeasy( Mini Kit (QIAGEN) according to the method described in the instruction manual. The total RNA was dissolved in sterile water ( 40  EL). Single-stranded cDNA was synthesized by RT-PCR using the SuperScript cDNA synthesis system (Invitrogen) with the purified RNA ( 1  to  2  pig) as template, according to the method described in the instruction manual.  7 - 2 . PCR amplification of antibody H chain variable region and sequence analysis As primers for amplifying the mouse antibody H chain variable region (VH) cDNA, an HB primer mixture and HF primer mixture described in the report by Krebber et al. (J. Immunol. Methods  1997 ;  201 :  35 - 55 ) were prepared. Using  0 . 5  gL each of the  100  gM HB primer mixture and  100  gM HF primer mixture, a reaction solution ( 25  gL) (cDNA solution prepared in  7 - 1  ( 2 . 5  EL), KOD plus buffer (TOYOBO),  0 . 2  mM dNTPs,  1 . 5  mM MgCl 2 ,  0 . 75  units DNA polymerase KOD plus (TOYOBO)) was prepared. Using a thermal cycler GeneAmp PCR system  9700  (Parkin Elmer), PCR was performed according to amplification efficiency of the cDNA fragments, either under conditions A ( 3  min heating at  98 ° C followed by  32  cycles of reaction ( 98 ° C,  20  sec,  58 ° C,  20  sec, and  72 ° C,  30  sec in one cycle)) or conditions B ( 3  min heating at  94 ° C followed by  5  cycles of reaction ( 94 ° C,  20  sec,  46 ° C,  20  sec, and  68 ° C,  30  sec in one cycle) and  30  cycles of reaction ( 94 ° C,  20  sec,  58 ° C,  20  sec, and  72 ° C,  30  sec in one cycle)). After PCR, the reaction solution was subjected to  1 % agarose gel electrophoresis. Amplified fragments of the desired size (about  400  bp) were purified using a QlAquick Gel Extraction Kit (QIAGEN) according to the methods described in the attached instruction manual, and eluted with sterile water ( 30  lIL). Nucleotide sequences of the DNA fragments were determined using a BigDye Terminator Cycle Sequencing Kit (Applied Biosystems) on a DNA sequencer ABI PRISM  3100  Genetic Analyzer (Applied Biosystems), according to the method described in the attached instruction manual. Sequence groups determined by this method were comparatively analyzed using an analytical software, GENETYX-SV/RC Version  6 . 1  (Genetyx), and DNAs with different sequences were selected.  7 - 3 . Preparation of antibody variable region DNA fragments for cloning The following procedure was performed to add restriction enzyme Sfi I cleavage sites for cloning to both termini of the antibody variable region amplification fragments. 
         [0234]    To amplify the VH fragments added with an Sfi I cleavage site (Sfi I-VH), a primer (primer VH- 5 ′ end) in which the primer HB (Gly 4 Ser) 2 -linker sequence was replaced with a sequence containing Sfi I cleavage site (SEQ ID NO:  31 ) was prepared. Using  0 . 5  pL each of the  10  liM sequence-specific primer VH- 5 ′ end and  10  gM primer scfor (J. Immunol. Methods  1997 ;  201 :  35 - 55 ), a reaction solution ( 20  pL) (purified solution of VH cDNA amplification fragment prepared in  7 - 2  ( 1  EL), KOD plus buffer (TOYOBO),  0 . 2  mM dNTPs,  1 . 5  mM MgCl 2 ,  0 . 5  units DNA polymerase KOD plus (TOYOBO)) was prepared. Using a thermal cycler GeneAmp PCR system  9700  (Parkin Elmer), PCR was performed according to amplification efficiency of the cDNA fragments, either under conditions A ( 3  min heating at  98 ° C followed by  32  cycles of reaction ( 98 ° C,  20  sec,  58 ° C,  20  sec. and  72 ° C,  30  sec in one cycle)) or conditions B ( 3  min heating at  94 ° C followed by  5  cycles of reaction ( 94 ° C,  20  sec,  46 ° C,  20  sec, and  68 ° C,  30  sec in one cycle) and  30  cycles of reaction ( 94 ° C,  20  sec,  58 ° C,  20  sec, and  72 ° C,  30  sec in one cycle)). After PCR, the reaction solution was subjected to  1 % agarose gel electrophoresis. Amplified fragments of the desired size (about  400  bp) were purified using a QlAquick Gel Extraction Kit (QIAGEN) by the method described in the attached instruction manual, and eluted with sterile water ( 30  EL). 
         [0235]    To amplify the mouse antibody L chain variable region (VL) cDNA fragments,  0 . 5  PL each of the 100 μM LB primer mixture and  100  pM LF primer mixture described in the report by Krebber et al. (J. Immunol. Methods  1997 ;  201 :  35 - 55 ) was first used, and a reaction solution ( 25  pL) (cDNA solution prepared in  7 - 1  ( 2 . 5  pL), KOD plus buffer (TOYOBO),  0 . 2  mM dNTPs,  1 . 5  mM MgCI 2 ,  0 . 75  units DNA polymerase KOD plus (TOYOBO)) was prepared. Using a thermal cycler GeneAmp PCR system  9700  (Parkin Elner), PCR was performed according to amplification efficiency of the fragments, under conditions of  3  minutes heating at  94 ° C. followed by  5  cycles of reaction ( 94 ° C,  20  sec,  46 ° C,  20  sec, and  68 ° C.,  30  sec in one cycle) and  30  cycles of reaction ( 94 ° C,  20  sec,  58 ° C,  20  sec, and  72 ° C.,  30  sec in one cycle). After PCR, the reaction solution was subjected to  1 % agarose gel electrophoresis. Amplified fragments of the desired size (about  400  bp) were purified using the QlAquick Gel Extraction Kit (QIAGEN) by the method described in the attached instruction manual, and eluted with sterile water ( 30  liL). The fragments are in a state in which the primer LF-derived (Gly 4 Ser) 3 -linker sequence is added to their C termini. In order to add an Sfi I cleavage site to the C termini of the fragments, a primer (primer VL- 3 ′ end) in which the primer LF (Gly 4 Ser) 3 -linker sequence was replaced with a sequence having Sfi I cleavage site (SEQ ID NO:  32 ) was prepared. To amplify the VL fragments added with an Sfi I cleavage site (Sfi I-VL),  0 . 5  pL each of the  10  IM VL- 3 ′ end primer mixture and  10  liM scback primer was used, and a reaction mixture ( 20  pL) (purified solution of VL cDNA amplification fragment ( 1  pL), KOD plus buffer (TOYOBO),  0 . 2  mM dNTPs,  1 . 5  mM MgCI 2 ,  0 . 5  units DNA polymerase KOD plus (TOYOBO)) was prepared. PCR was performed using a thermal cycler GeneAmp PCR system  9700  (Parkin Elmer) under conditions of  3 -minutes heating at  94 ° C followed by  5  cycles of reaction ( 94 ° C,  20  sec,  46 ° C,  20  sec, and  68 ° C,  30  sec in one cycle) and  30  cycles of reaction ( 94 ° C,  20  sec,  58 ° C,  20  sec, and  72 ° C,  30  sec in one cycle). After PCR, the reaction solution was subjected to  1 % agarose gel electrophoresis. Amplified fragments of the desired size (about  400  bp) were purified using the QlAquick Gel Extraction Kit (QIAGEN) by the method described in the attached instruction manual, and eluted with sterile water ( 30  EL). 
         [0236]    The purified Sfi I-VH and Sfi I-VL fragments were digested with Sfi I (Takara Bio) at  50 ° C overnight in a reaction solution prepared according to the method described in the attached instruction manual. Subsequently, the reaction solution was purified using a QIAquick PCR Purification Kit (QIAGEN) by the method described in the attached instruction manual, and eluted with Buffer EB ( 30  AL) included in the kit.  7 - 4 . Human IgG 4 -Mouse chimera bispecific IgG antibody expression plasmid When producing the bispecific IgG antibody of interest, the knobs-into-holes technique of IgGl (Ridgway et al., Protein Eng.  1996 ;  9 :  617 - 621 ) was referred to when preparing IgG 4  with an amino acid-substituted CH 3  portion to form heteromolecules for each H chain. Type a (IgG 4 ya) is substituted with Y 349 C and T 366 W, and type b (IgG 4 yb) is substituted with E 356 C, T 366 S, L 368 A, and Y 407 V. Further, a substitution (-ppcpScp- -&gt;-ppcpPcp-) was also introduced at the hinge regions of both types. Almost all the H chains become heteromolecules by this technique; however, this does not necessarily apply to L chains, and the formation of unnecessary antibody molecules may affect subsequent activity measurements. Therefore, to separately express the arms of each antibody molecule (called HL molecule), which have different specificities, and efficiently form the type of bispecific IgG antibody of interest within cells, those that are inducible by different drugs were used as the expression vectors for each HL molecule. 
         [0237]    As an expression vector for an arm of the antibody molecule (called right arm HL molecule for convenience), pcDNA 4 -g 4 H or pcDNA 4 -g 4 L ( FIG. 1  or  FIG. 2 ) was prepared, in which the respective H chain or L chain region, that is, an appropriate mouse antibody variable region (VH or VL) and a human IgG 4 ya constant region (SEQ ID NO:  33 ) or K constant region (SEQ ID NO:  34 ), were incorporated into the tetracycline-inducible type vector pcDNA 4  (Invitrogen) downstream of the signal sequence (IL 3 ss) for animal cells (Proc. Natl. Acad. Sci. USA.  1984 ;  81 :  1075 ). First, Eco RV and Not I (Takara Bio) were used to digest pcDNA 4  at the restriction enzyme cleavage sites that are present in its multi-cloning site. The right arm H chain- or L chain-expression unit (about  1 . 6  kb or about  1 . 0  kb respectively) of a chimera bispecific antibody having appropriate antibody variable regions was digested with Xho I (Takara Bio). Then, it was purified with the QIAquick PCR Purification Kit (QIAGEN) by the method described in the attached instruction manual, and reacted with DNA polymerase KOD (TOYOBO) at  72 ° C for  10  minutes in a reaction solution composition described in the attached instruction manual to blunt the ends. The blunt-end fragments were purified with the QIAquick PCR Purification Kit (QIAGEN) by the method described in the attached instruction manual, and digested with Not I (Takara Bio). The Not lfblunt end fragments (about  1 . 6  kb or  1 . 0  kb respectively) and the Eco RV/Not I-digested pcDNA 4  were subjected to a ligation reaction using Ligation High (TOYOBO), according to the method described in the attached instruction manual. An E. coli DH 5 ( strain (Competent high DH 5 c (TOYOBO)) was transformed with the above- described reaction solution. From the ampicillin-resistant clones thus obtained, respective plasmid DNAs were isolated using the QlAprep Spin Miniprep Kit (QIAGEN). 
         [0238]    As an expression vector for the antibody molecule&#39;s other arm (called left arm HL molecule for convenience), pIND-g 4 H or pIND-g 4 L ( FIG. 2  or  FIG. 3 ) was prepared according to the above-described method, in which the H chain or L chain respective region, that is, an appropriate mouse antibody variable region (VH or VL) and a human IgG 4 yb constant region (SEQ ID NO:  35 ) or K constant region (SEQ ID NO:  34 ), were incorporated into the ecdysone analogue inducible type vector pIND (Invitrogen) downstream of the signal sequence (IL 3 ss) for animal cells (EMBO. J.  1987 ;  6 :  2939 ), and the respective plasmid DNAs were isolated.  7 - 5 . Construction of bispecific antibody expression vector The tetracycline-inducible type expression plasmid prepared in  7 - 4  (pcDNA 4 -g 4 H or pcDNA 4 -g 4 L) was digested with Sfi I, and was subjected to  1 % agarose gel electrophoresis. Fragments (about  5  kb) lacking the intrinsic antibody variable region part (VH or VL (see  FIG. 1  or  FIG. 2 )) were purified using the QlAquick Gel Extraction Kit (QIAGEN) by the method described in the attached instruction manual, and eluted with sterile water ( 30   4 L). The fragments, and the corresponding Sfi I-VH or Sfi-VL fragment derived from the Sfi I-digested anti-F.IXa antibody prepared in  7 - 3 , were subjected to a ligation reaction using the Quick Ligation Kit (New England Biolabs) according to the method described in the attached instruction manual. An E. coli DH 5 c strain (Competent high DHSa (TOYOBO)) was transformed with the above-described reaction solution. Further, fragments obtained by removing the antibody variable region part by a similar technique as described above (VH or VL (see  FIG. 2  or  FIG. 33 )) from the Sfi I-digested ecdysone analogue-inducible type expression plasmid (pIND-g 4 H or pIND- 4 GL) prepared in  7 - 4  and the corresponding Sfi I-digested anti-F.X antibody-derived Sfi I-VH or Sfi I-VL fragment prepared in  7 - 3  were incorporated by a similar method. 
         [0239]    In each of the ampicillin-resistant transformants thus obtained, insertion of the fragment of interest was confirmed by colony PCR method using primers that sandwich the inserted fragment. First, for the anti-F.IXa antibody chimeric H chain or L chain expression vector, a  21  - mer CMVF primer (SEQ ID NO:  36 ) which anneals to the CMV forward priming site upstream of the insertion site, and an  1   8 -mer BGHR primer (SEQ ID NO:  37 ) which anneals to the BGH reverse priming site downstream of the insertion site were synthesized (Sigma Genosys). For the anti-F.X antibody chimeric H chain or L chain expression vector, a  24 -mer EcdF primer (SEQ ID NO:  38 ), which anneals to the upstream of the insertion site and an  1   8 -mer BGHR primer (SEQ ID NO:  37 ) which anneals to the BGH reverse priming site downstream of the insertion site were synthesized (Sigma Genosys). For colony PCR, a reaction solution ( 20  JIL) ( 0 . 2  VL primer ( 10  ELM), KOD dash buffer (TOYOBO),  0 . 2  mM dNTPs, and  0 . 75  units DNA polymerase KOD dash) (TOYOBO)) was prepared. To this reaction solution, cells of the transformant strain were added in appropriate amounts and PCR was performed. PCR was performed using a thermal cycler GeneAmp PCR system  9700  (Parkin Elmer) under conditions of  1  minute heating at  96 ° C followed by  30  cycles of reaction ( 96 ° C,  10  sec,  55 ° C,  10  sec, and  72 ° C,  30  sec in one cycle). After PCR, the reaction solution was subjected to  1 % agarose gel electrophoresis, and clones from which amplification fragments of the desired size were obtained were selected. The PCR product was treated with an ExoSAP-IT (Amersham Biosciences) to inactivate excess primers and dNTPs according to the attached instruction manual. Nucleotide sequences of the DNA fragments were determined using a BigDye Terminator Cycle Sequencing Kit (Applied Biosystems) on a DNA sequencer ABI PRISM  3100  Genetic Analyzer (Applied Biosystems), according to the method described in the attached instruction manual. Sequence groups determined by the present method were analyzed with an analytical software, GENETYX- SV/RC Version  6 . 1  (Genetyx). For VH, clones of interest having no insertion, deletion, or mutation were selected. For VL, different from the P 3 U 1  -derived pseudo VL gene used in hybridomas, clones of interest having no insertion, deletion, or mutation were selected. 
         [0240]    From the clones of interest, the respective plasmid DNAs were isolated by using a QlAprep Spin Miniprep Kit (QIAGEN), and then dissolved in sterile water ( 100  JIL). Anti- F.IXa antibody chimeric H chain expression vector, anti-F.IXa antibody chimeric L chain expression vector, anti-F.X antibody chimeric H chain expression vector, and anti-F.X antibody chimeric L chain expression vector were named pcDNA 4 -g 4 IXaHn, pcDNA 4 -g 4 IXaLn, pIND- g 4 XHn, and pIND-g 4 XLn, respectively. Each plasmid solution was stored at  4 ° C till use. [Example  8 ] Expression of chimera bispecific antibodies in animal cells  8 - 1 . Preparation of DNA solutions Expression of the antibody&#39;s right arm HL molecule expression vectors (pcDNA 4 - g 4 IXaHn and pcDNA 4 -g 4 IXaLn) is induced by tetracycline. In the absence of tetracycline, Tet repressor-encoding plasmid pcDNA 6 /TR (Invitrogen) is required to completely suppress their expressions. Further, expression of the left arm antibody HL molecule expression vectors (pIND-g 4 XHn and pIND-g 4 XLn) was induced by an insect hormone ecdysone analogue (ponasterone A). This requires plasmid pVgRXR (Invitrogen) which encodes the ecdysone receptor and retinoid X receptor that react with ponasterone A and induce expression. Therefore, for the transfection of animal cells, a mixture of six types of plasmid DNAs in total was prepared. For  1  mL of cell culture, pcDNA 4 -g 4 IXaHn, pcDNA 4 -g 4 IXaLn, pIND-g 4 XHn and pIND- g 4 XLn ( 218 . 8  ng each), as well as pcDNA 6 /TR and pVgRXR ( 1312 . 5  ng each) were used.  8 - 2  Transfection of animal cells A HEK 293 H strain (Invitrogen) derived from human fetal renal cancer cells was suspended in DMEM medium (Invitrogen) containing  10 % FCS (MOREGATE), plated onto each well of a  12 -well plate for cell adhesion at a cell density of  5  x  1  cells/mL, and cultured in a CO 2  incubator ( 37 ° C,  5 % CO 2 ). The plasmid DNA mixture prepared in  8 - 1  was added to a mixed solution of transfection reagent Lipofectamine  2000  ( 7  jL; Invitrogen) and Opti-MEM I medium ( 250  liL; Invitrogen) and left to stand at room temperature for  20  minutes. This mixed solution was added to cells in each well, and the cells were incubated in a C 0   2  incubator ( 37 ° C,  5 % CO 2 ) for four to five hours.  8 - 3  Induction of bispecific IgG antibody expression After the medium was removed by suction from the above transfected cell cultures, I mL CHO-S-SFM-II (Invitrogen) medium containing  1  gg/mL tetracycline (WAKO Pure Chemical Industries) was added, and primary expression of the antibody&#39;s right arm HL molecule was induced by culturing the cells in a C 0   2  incubator ( 37 ° C,  5 % CO 2 ) for one day. Subsequently, the medium was removed by suction, and the cells were washed once with  1  mL of CHO-S-SFM-II medium, and cultured in a C 0   2  incubator ( 37 ° C,  5 % CO 2 ) for  2  or  3  days following the addition of  1  mL of CHO-S-SFM-II medium containing  5  gM ponasterone A (Invitrogen), and secondary expression of the antibody&#39;s left arm HL molecule was induced for secretion of the bispecific IgG antibody into the medium. The collected culture supematant was centrifuged (approximately  2000 g,  5 min, room temperature) to remove the cells, and concentrated as needed by Microcon(R) YM- 50  (Millipore). The samples were stored at  4 ° C till use. [Example  9 ] Quantification of human IgG concentration Goat affinity purified antibody to human IgG Fc (Cappel) was prepared at  1  gg/mL with a coating buffer, and solid-phased onto a Nunc-Immuno plate. After blocking with a diluent buffer (D.B.), samples of culture supernatants appropriately diluted with D.B. were added. As a standard for calculating the antibody concentration, human IgG 4  (humanized anti-TF antibody, see WO  99 / 51743 ) diluted with D.B. in a  2 -fold dilution series with  11  levels from  1000  ng/mL was similarly added. After three washes, alkaline phosphatase goat anti-human IgG (Biosource International) was added for reaction. After five washes, the plate was color developed using the Sigma  104 (R) phosphatase substrate (Sigma-Aldrich) as a substrate, and the absorbance at  405  nm was measured on an absorbance reader Model  3550  (Bio-Rad Laboratories) with a reference wavelength of  655  nm. Using the Microplate Manager III (Bio-Rad Laboratories) software, human IgG concentration in the culture supernatant was calculated from the standard curve. [Example  10 ] F.VIIIa (activated coagulation factor VIII)-mimetic activity assay The F.VIIIa-mimetic activity of a bispecific antibody was assessed by the following enzymatic assay. The following reactions were all performed at room temperature. A mixed solution of  40  jL Factor IX ( 3 . 75  jg/mL; Enzyme Research Laboratories) and  10  lL of the antibody solution was incubated in a  96 -well plate for one hour. Then,  10  gL Factor XIa ( 10  ng/mL; Enzyme Research Laboratories),  20   1 L Factor X ( 50  jg/mL; Enzyme Research Laboratories),  5  lL phospholipid ( 400  tg/mL; see Example  5 - 3 ), and  15  lL TBSB containing  5 mM CaCl 2  and I mM MgCl 2  (hereinafter abbreviated as TBSB-S) were added to initiate the enzymatic reaction. After one hour, the reaction was stopped by adding  10  VL of  0 . 5 M EDTA. 
         [0241]    After adding a colorimetric substrate solution ( 50  pL) to each well, absorbance at  405  nm (reference wave length  655  nm) was measured at  0  and  30  minutes with a Model  3550  Microplate Reader (Bio Rad Laboratories). The F.VIIIa-mimetic activity was presented as a value obtained by subtracting the value of absorbance change in  30  minutes without antibody addition from that with the antibody addition (see  FIG. 4  and  FIG. 5 ). 
         [0242]    TBSB was used as a solvent for phospholipids, while TBSB-S was used as a solvent for Factor Xla, Factor IX, and Factor X. The colorimetric substrate solution was a  1 : 1  mixture of “Tesutochimu” colorimetric substrate S- 2222  (Chromogenix) dissolved according to the attached instruction manual and a polybrene solution ( 0 . 6  mg/L hexadimethrine bromide (Sigma)). 
         [0243]    Further, the concentration dependency of XB 12 /SB 04 &#39;s F.VIIIa-mimetic activity, which was the highest among all, was measured ( FIG. 6 ). [Example  11 ] Plasma coagulation assay 
         [0244]    To elucidate whether a bispecific antibody corrects the coagulation ability of hemophilia A blood, effects of the bispecific antibody on activated partial thromboplastin time (APTT) were examined using F.VIII-deficient plasma. A mixed solution comprising an antibody solution at various concentrations ( 50  pL), F.VIII-deficient plasma ( 50  liL; Biomerieux) and APTT reagent ( 50  lL; Dade Behring) was warmed at  37 ° C for  3  minutes. Coagulation reaction was initiated by adding  20  mM CaCl 2  ( 50  VL; Dade Behring) to the above-described mixture. The time required for coagulation was measured with CR-A (Amelung)-connected KC  1  OA (Amelung) ( FIGS. 7 and 8 ). 
         [0245]    Further, XB  12 /SB 04 , which showed the highest coagulation time-shortening activity, was measured for its concentration dependency ( FIG. 9 ). 
       Example  12    
     Antibody Purification 
       [0246]    The culture supematant ( 10  mL) obtained by the method described in Example  8  was concentrated to  1  mL with Centricon(R) YM- 50  (Millipore). To this concentrate,  10 % BSA ( 10  ItL),  1 % Tween(R)  20  ( 10  tL), and rProtein A Sepharosem Fast Flow (Amersham Biosciences) ( 100  pL) were added, and the solution was mixed by overturning at  4 ° C overnight. The solution was transferred to an Ultrafree(R)-MC  0 . 22  gm filter cup (Millipore), and after washing with TBS containing  0 . 01 % Tween(R)  20  ( 500  SAL) thrice, the rProtein A Sepharosem resin was suspended in  100  ;L of  0 . 01 % Tween(R)  20  (pH  2 . 0 ) containing  10  mM HCI, and left to stand for  3  minutes. Then, the antibody was eluted, and the eluate was immediately neutralized with the addition of  5  pL IM Tris-HCI, pH  8 . 0 . Using the Microplate Manager III (Bio-Rad Laboratories) software, the human IgG concentration was calculated from the standard curve. The antibody. concentration was quantified according to Example  9 . 
       INDUSTRIAL APPLICABILITY  
       [0247]    The present invention provides bispecific antibodies that have the effect of functionally substituting for ligands of heteromolecule-comprising receptors. 
         [0248]    The present invention also provides bispecific antibodies that recognize both an enzyme and its substrate, and which functionally substitute for a cofactor that enhances the enzymatic activity. 
         [0249]    The bispecific antibodies according to the present invention are thought to have high stability in blood and low antigenicity. Thus, it is greatly expected that they will become pharmaceuticals.