bluuebunny/crossref_metadata_2025 huggingface dataset:
Various expressions of a unique anti‐human thyroglobulin antibody repertoire in normal state and autoimmune disease
Authors: Ruf Jean , Carayon Pierre , Lissitzky Serge
Published: February 2007

Polyclonal anti‐human thyroglobulin (hTgb) antibodies (Ab) were purified from sera of rabbits immunized with human thyroglobulin, normal humans and patients suffering from Graves' disease, Hashimoto's thyroiditis and thyroid carcinoma. The avidity of the various Ab preparations for hTgb ranged from 0.3 × 1010−2.2 × 1010 M−1. By using well characterized mouse monoclonal antibodies (mAb) directed against hTgb, it was shown that the fine specificities of induced anti‐hTgb Ab in rabbits, natural Ab in normal subjects and autoantibodies in diseased patients were similar; however, they differed from that of rabbit anti‐bovine and anti‐porcine thyroglobulin Ab which were able to inhibit the hTgb binding of only a few of the mAb. Anti‐hTgb in rabbits and in patients with thyroid carcinoma varied from those in normal subjects only by uniformly elevated serum titers. In contrast, patients with Graves' disease and Hashimoto's thyroiditis showed an increased concentration essentially restricted to Ab reacting with few of the antigenic determinants recognized by the mAb. Our data suggest that the repertoire of anti‐hTgb Ab is similar in mouse, rabbit and human. Furthermore, the finding of identical fine specificities for anti‐hTgb Ab in normal and pathological conditions implies that autoantibodies are produced in normal subjects and held to a low level by regulatory processes which fail with respect to selected epitopes in autoimmune diseases.
Induction of an auto‐anti‐IgE response in rats. I. Effects on serum IgE concentrations
Authors: Marshall Jean S. , Bell Eric B.
Published: February 2007

With a view to specifically suppressing the IgE isotype, rats of high (BN) and low (PVG. RT1u) IgE‐responding phenotypes were immunized with a highly purified rat IgE myeloma (IR2) in an attempt to induce an anto‐anti‐IgE response. Rat IgE antibodies against ϵ determinants were detected in the serum of IR2‐immunized animals using a solid‐phase (plate) radioimmunoassay. The auto‐anti‐IgE antibodies detected were found to bind to IR2, to a second rat IgE myeloma (IR162) and to mouse monoclonal IgE but not rat IgG. The specificity of the anti‐ϵ binding was shown by inhibition studies. The raising of an auto‐anti‐IgE response in PVG. RT1u rats severely depleted the serum level of circulating IgE for at least 8 weeks. In BN rats, immunization with IR2 caused marked fluctuations in serum IgE levels. The rats in both strains remained healthy throughout the experiment. The rate and route of IgE break down was not altered in anti‐IgE‐producing rats. The relevance of the present model in understanding and possibly controlling allergic disorders is consid‐ ered.
Mapping cell surface antigens on mouse pre‐B cell lines
Authors: McKearn John P. , Rosenberg Naomi
Published: February 2007

Characterization of cell surface molecules expressed by B cell precursors has been hampered by the inability to routinely assay such cells from freshly explanted normal lymphoid tissues. However, a large number of transformed pre‐B cell clones have been isolated which presumably include those precursors recently entering the B cell lineage (obtained from fetal liver and more rarely from adult bone marrow) and extending to those clones which are poised to become surface Ig‐positive B cells. In this report, we have quantitated expression of 10 different cell surface molecules, 5 of which bear special interest as B cell differentiation antigens, among a large panel of pre‐B cell clones.
Polyclonal activation of the murine immune system by an antibody to IgD. VI. Influence of doses of goat anti‐mouse δ chain and normal goat IgG on B lymphocyte proliferation and differentiation
Authors: Finkelman Fred D. , Smith Joanne , Villacreses Nelly , Metcalf Eleanor S.
Published: February 2007

The injection of mice with 800 μg of an affinity‐purified goat antibody to mouse IgD (GaMδ) induces early, T‐independent polyclonal increases in the expression of B cell surface Ia, and B cell size and DNA synthesis, as well as later, T‐dependent polyclonal increases in spleen cell number and Ig secretion. We have now studied the effects of varying the doses of injected GaMδ on all phases of B cell activation, as well as the effects of supplementing GaMG with varying quantities of normal goat IgG (GIgG). We have found that while 12.5 μg of GaMδ modulates most of the IgD from the surface of splenic B lymphocytes, it fails to activate these cells. Increases in the expression of B cell surface Ia are first seen when 50 μg of GaMδ is injected, while increases in B cell DNA synthesis usually require the injection of 200 μg of GaMδ and peak with doses of approximately 800 μg. Increases in splenic B cell number and DNA synthesis during the T‐dependent phase of GaMδ‐induced B cell activation are seen only in those mice that were injected with sufficient quantities of GaMδ to induce DNA synthesis during the T‐independent phase. Supplementing the dose of GaMδ injected with additional GIgG has no significant effect on B cell DNA synthesis or B cell number but dramatically increases polyclonal IgGl secretion. Although mice which have been injected with 50 μg of GaMδ or with 800 pμ of GIgG alone have few polyclonal IgG1‐secreting cells, substantial increases in the number of IgG1,‐ secreting cells are seen in mice injected with 50 μg of GaMδ plus 750 μg of GIgG. GIgG and larger doses of GaMδ similarly act synergistically to increase polyclonal IgGl secretion. In contrast to the induction of polyclonal IgGl secretion, the stimulation of polyclonal IgM secretion requires the injection of mitogenic doses of GaMδ and is not enhanced by the injection of additional GIgG. These observations suggest that, in this model system, stimulatory signals that activate B cells through their surface Ig are limiting for the induction of polyclonal proliferation and IgM secretion, while the generation of T helper lymphokines that do not directly interact with B cells through their surface Ig may be more limiting for the stimulation of polyclonal IgGl secretion.
Constraints in T‐B cooperation related to epitope topology on E. coli β‐galactosidase. I. The fine specificity of T cells dictates the fine specificity of antibodies directed to conformation‐ dependent determinants
Authors: Manca Fabrizio , Kunkl Annalisa , Fenoglio Daniela , Fowler Andrée , Sercarz Eli , Celada Franco
Published: February 2007

Experiments to test the relationship between the epitopes on a protein antigen recognized by T and B cells in their collaboration to produce antibody cannot rely solely on hapten‐carrier models. In the present work we used E. coli β‐galactosidase, a molecule whose tertiary and quaternary epitopes have been well characterized, as the model antigen. T helper cells were raised by stimulating mice with the intact or the denatured molecule or with any of several β‐galactosidase cyanogen bromide pep‐ tides. In a series of in vitro helper T cell assays we confronted the various T popula tions with B cells preimmunized with the native antigen, and we tested their capacity to help production of (a) binding antibodies and (b) antibodies directed to single conformational epitopes, characterized by their capacity to protect the enzyme from heat denaturation or to activate defective P‐galactosidase. According to our results, (a) equivalent T cell help can be provided by T helper cells primed with native or denatured antigen, even for the production of “conformational” antibodies; (b) one of the peptides (CB‐18) is most efficient in raising help for binding antibodies; and (c) two peptides (CB‐20 and CB‐21) rank highest in priming T helper cells for the even‐ tual production of protecting and activating antibodies, respectively. Thus, not every β‐galactosidase‐specific T helper cell is useful in providing help to B cells specific for any particular epitope on the molecule, but rather preferential pairings exist, possibly governed by a proximity rule.
Autoantibodies to anti‐DNA with anti‐allotypic and anti‐idiotypic specificities in (NZB × NZW)F1 mice
Authors: Eilat Dan , Fischel Ruth , Zlotnick Avinoam
Published: February 2007

The monoclonal A52 (IgG2b, x) anti‐DNA autoantibody represents a major cross‐ reactive idiotype in the murine and human autoimmune response to DNA. Examination of sera and purified IgG derived from (NZB × NZW)Fj mice showed that these mice develop an age‐dependent binding reactivity with the pure anti‐DNA IgG. Three monoclonal antibodies possessing this reactivity were prepared from unprimed female (NZB × NZW)F1 mice. One of these monoclonal antibodies appeared to be directed against allotypic determinants present in the NZB IgG2b the other two antibodies exhibited a marked preference for idiotypic determinants of the A52 IgG. The IgG anti‐allotype and anti‐idiotype activities in (NZB × NZW)Ft mice may, therefore, represent the products of a deregulated immune system and/or constitute the normal elements of a functional immune regulation system.
The respiratory burst is not required for killing of intracellular and extracellular parasites by a lymphokine‐activated macrophage cell line
Authors: Scott Phillip , James Stephanie , Sher Alan
Published: February 2007

The macrophage cell line, IC‐21, was found to be incapable of producing the oxygen products associated with the respiratory burst. However, IC‐21 cells were activated by lymphokine (LK) to kill intracellular (Leishmania donovani amastigotes) and extracellular (Schistosoma mansoni larvae) parasites, as well as tumor cells. In each case, the cytotoxicity exhibited by activated IC‐21 cells and activated peritoneal mac‐ rophages was indistinguishable. However, nonactivated IC‐21 cells were unable to kill L. donovani log‐growth phase promastigotes, while nonactivated peritoneal mac‐ rophages destroyed > 90% of the initial infection. These results indicate that amasti‐ gotes and schistosome larvae are susceptible to killing by nonoxidative cytotoxic mechanism induced by lymphokine activation but, on the other hand, support the concept that the killing of log‐growth phase promastigotes by nonactivated cells is dependent upon the respiratory burst. We propose that the IC‐21 cell line may be a useful model for studying nonoxidative killing functions of activated macrophages.
Partial biochemical characterization of IgG1‐inducing factor
Authors: Sideras Paschalis , Bergstedt‐Lindqvist Susanne , Severinson Eva
Published: February 2007

IgG1, induction factor elevates the IgGl and suppresses the IgG3 and IgG2b responses in lipopolysaccharide‐stimulated murine spleen cell cultures. By the use of a quantitative assay, it was found that the three activities, induction of IgG1 and reduction of IgG3 and IgG2b synthesis, were found in the same fractions after different chromato‐graphic procedures, suggesting that the same molecule was responsible for the effects. The factor was precipitated by 60‐90% saturation of ammonium sulfate and was sensitive to proteolytic cleavage and to treatment with a buffer of pH 10. It had an apparent molecular mass of 20 kDa as judged by gel filtration chromatography and was separated into two peaks after isoelectric focusing, PI 7.4‐7.2 and 6.4‐6.2, respectively. Finally it was weakly hydrophobic and negatively charged at pH 7.55. These characteristics indicate that the factor is different from many previously characterized lymphokines and similar or identical to the B cell stimulating factor‐1 (BSF‐pl). The relevance of these findings to the mechanism of the immunoglobulin class switch is discussed.
Regulation of pre‐B cell proliferation in bone marrow: immunofluorescence stathmokinetic studies of cytoplasmic p chain‐bearing cells in anti‐IgM‐treated mice, hematologically deficient mutant mice and mice given sheep red blood cells
Authors: Opstelten Davine , Osmond Dennis G.
Published: February 2007

To identify factors influencing the in vivo proliferate activity of bone marrow pre‐B cells, the metaphase‐blocking drug, vincristine sulfate, was injected into (a) mice depleted of B lymphocytes by treatment with anti‐mouse IgM antibodies from birth; (b) hematologically deficient WWv and SI/SId mutants, and (c) mice injected with a foreign agent, sheep red blood cells (SRBC). Subsequently, a quantitative measure of pre‐B cell proliferation was provided by examining marrow cells by immunofluorescence labeling for the absolute number of pre‐B cells, identified by the presence of cytoplasmic μ chains (cμ) without surface μ (sμ), which had been arrested in meta‐phase. In anti‐IgM‐treated mice, some changes were observed in the size of the large pre‐B cell population and in the incidence of mitotic cells after vincristine administration, but the overall production rate of pre‐B cells did not differ from that in controls given normal rabbit serum. Pre‐B cell kinetics in WW and SI/SId mice also generally resembled those in homozygous controls. In contrast, after SRBC injection, there was an increase in the rate at which large pre‐B cells entered mitosis. Thus, the proliferation of cμ+sμ‐ bone marrow pre‐B cells shows no evidence of feedback control from the mature B lymphocyte pool, as indicated by lack of stimulation of pre‐B cell production in anti‐IgM‐treated mice, and is independent of the hemopoietic defects of WW or SI/SId mutants. On the other hand, the increased bone marrow pre‐B cell proliferation after SRBC injection demonstrates that the magnitude of B cell genesis in the bone marrow can be influenced by extrinsic agents and thus may be influenced by environmental stimuli.
Purine nucleotide metabolism in resident and activated rat macrophages in vitro
Authors: Barankiewicz Jerzy , Cohen Amos
Published: February 2007

The overall purine metabolism was studied in detail in resident peritoneal macrophages (MO) and in thioglycolate elicited peritoneal Mϕ in vitro. The salvage of purine bases (adenine, hypoxanthine and guanine) was active in both Mϕ populations, whereas purine biosynthesis de novo was low. Purine nucleosides (inosine, guanosine and adenosine) were efficiently degraded to uric acid and only adenosine was directly salvaged into nucleotides. Purine salvage was markedly increased in elicited Mϕ as compared to resident Mϕ whereas purine degradation pathways were enhanced only slightly. These results clearly indicate that salvage of purine bases is the main source for purine nucleotide biosynthesis in Mϕ, but nucleotide catabolism is the predominant pathway.
Receptors for immunoglobulin isotypes (FcR) on murine T cells: II. Multiple FcR induction on hybridoma T cell clones
Authors: Daeron Marc , Neauport‐Sautès Catherine , Yodoi Junji , Moncuit Janine , Fridman Wolf H.
Published: February 2007

In the preceding report (Eur. J. Immunol.1985. 75: 662), we described a variety of receptors for the Fc portion of the different isotypes of mouse immunoglobulins (FcR), that were found to be expressed on hybridoma T cell clones. In the present work, we wondered whether the expression of these T cell FcR would be regulated by environmental influences such as the presence of corresponding ligands. We found that exposing the cells to the bulk of serum immunoglobulins in vivo, or to purified monoclonal immunoglobulins in vitroboth resulted in FcR induction. The expression of all constitutive receptors, i.e.Fcγ1/2bR, Fcγ3R, FcαR and FcϵR, could be increased upon incubation with IgG1, IgG2b, IgG3, IgA and IgE, respectively. After induction, the specificity of FcR was not modified. Two FcR were detectable only upon induction. These were Fcγ2a/2b/1R, induced by IgG2a and FcμR, induced by IgM. Interestingly, FcR detectable after induction only were short‐lived at the membrane. Ten to 15 h after induction they were not detected any more, whereas the expression of constitutive FcR remained elevated for at least 24 h following induction.

Therefore, depending on the concentration of immunoglobulins in the environment, and depending on whether they are short lived or long lived, FcR can modulate their expression on the membrane of T cells. Such a versatility might be an efficient means to contribute to isotypic regulation through the release of regulatory immunoglobulin‐ binding factors.
A high incidence of cross‐reactive idiotypes among murine natural autoantibodies
Authors: Lymberi Peggy , Dighiero Guillaume , Ternynck Thérèse , Avrameas Stratis
Published: February 2007

Anti‐idiotypic (anti‐Id) antibodies were produced in rabbits against two natural monoclonal IgM autoantibodies (NmAb), D23 and E7, which exhibited a broad reactivity and were derived from fusions of spleen cells from adult unprimed B ALB/c mice and nonsecreting myeloma cell lines. They were used to test the reactivities of 12 NmAb obtained from adult and newborn unprimed mice. Both anti‐Id recognized cross‐reactive idiotopes frequently shared by NmAb; 8 out of the 12 NmAb reacted with anti‐IdD23, while 5 of them also reacted with anti‐IdE7. All of the Id‐bearing antibodies possessed widespread reactivity with structurally dissimilar self and non‐ self antigens. In most cases, their cross‐reactive Id determinants seemed to be located outside of their antigen‐binding sites. Furthermore, the presence in normal mouse sera of significant levels of D23 and E7 idiotopes correlated with the presence of natural antibody activity and was mainly associated with IgM and IgG2b fractions. Finally, D23 idiotope(s) were also found on induced murine anti‐myosin antibodies. The high incidence of cross‐reactive idiotopes found among NmAb produced by clones derived from different mice and their presence in normal BALB/c mouse serum Ig fractions suggest that families of germ‐line genes may encode for at least a part of them.
Growth of normal human T lymphocytes induced by monoclonal antibody to the T cell antigen receptor
Authors: Boylston Arthur W. , Cosford Paul
Published: February 2007

A monoclonal antibody (mAb) called 30‐3D6 has been raised against the T cell antigen receptor analogue on a human T cell leukemia cell line HPB‐ALL. This mAb comodulates the T3 molecule on HPB‐ALL and precipitates the heterodimeric structure previously described as a T cell idiotypic receptor analogue on this cell line. 30‐3D6 reacts with a variable percentage of normal T cells (up to 6%) depending on the donor and this number is stable on repeated sampling and is not affected by the temperature of the reaction. When normal T cells from a high frequency donor are stimulated with 30‐3D6 and interleukin 2 in vitro the idiotype‐positive (Id+) population can be expanded. Large numbers of > 90% Id+ T cells can be generated. Id cells are present in both the helper and cytotoxic suppressor subsets.
Senescence of a human lymphoblastoid clone producing anti‐Rhesus(D)
Authors: Melamed Mark D. , Gordono John , Ley Steven J. , Edgar David , Hughes‐Jones Nevin C.
Published: February 2007

The exploitation of Epstein‐Barr virus transformation to generate human lymphoblastoid clones (LCL) producing antibody of predefined specificity has proved highly inefficient, Observations reported here on a cloned LCL producing anti‐Rhesus(D) may provide an explanation for the low success rate. Over a few months this clone manifested a progressive loss of capacity to maintain growth in culture. Evidence consistent with terminal differentiation to a cell with the properties of a nonproliferating plasma cell was obtained. These late cells differed from those in the earlier actively cycling phase in that they were no longer able to respond to autostimulatory growth factors although they continued to produce them. This irreversible senescence leading to the death of the clone may be a common feature of virally transformed B cells and this would explain many of the difficulties encountered on this route to the production of human monoclonal antibodies.
Major surface protein of Toxoplasma gondii (p30) contains an immunodominant region with repetitive epitopes
Authors: Rodriguez Céste , Afchain Daniel , Capron André , Dissous Colette , Santoro Ferrucio
Published: February 2007

Four monoclonal antibodies (mAb) against surface antigens of tachyzoites of Toxoplasma gondii were produced. Immunoprecipitation of extracts of 125I‐labeled tachyzoites identified the same polypeptide with apparent molecular weight of 30 000 (p30). A competition binding assay indicated that a single region of p30 was recognized by all 4 of the mAb. Furthermore, we found that single mAb inhibited 25–50% of the specific binding of antibodies of patients with toxoplasmosis to the antigenic extract of tachyzoites. It appears, therefore, that p30 is the most immunogenic constituent of tachyzoites, and that a single region of this molecule contains most of the immunogenic activity. Finally, a two‐site/one‐antibody immunoradiometric assay with the same mAb indicated that the p30 molecule is multivalent with respect to the expression of a single epitope.
A monoclonal λ1‐bearing anti‐dextran antibody from a λ‐defective mouse strain
Authors: Weissn Siegfried , Lehmann Kathrin , Cohn Melvin
Published: February 2007

A hybridoma from the λ‐defective mouse strain SJA has been established. It produces a λ1‐bearing IgG2b, dextran B 1355‐binding antibody. The DNA sequence of the VJ and C gene segment was in complete accordance with the published germ‐line sequence. The rate of secretion and the steady state level of cytoplasmic RNA of this line was comparable to that of cell lines from normal mice. The idiotype was closely related to that of MOPC 104E indicating that the λ1 light chain is associated with the same VH region and in a similar fashion as in BALB/c mice. This antibody should be useful for further experiments on the λ defect of SJL or SJA mice.
Antigen stimulation of cytolytic T lymphocyte precursors: minimal requirements for growth and acquisition of cytolytic activity
Authors: Erard François , Nabholz Markus , Robson MacDonald H.
Published: February 2007

Minimal requirements for growth and acquisition of cytolytic activity by alloantigenstimulated cytolytic T lymphocyte precursors (CTL‐P) have been investigated. CTL‐P from C57BL/6 spleen were purified by staining with monoclonal anti‐Lyt‐2 antibodies followed by positive selection on a fluorescence‐activated cell sorter. Microcultures containing 2000 purified Lyt‐2+ cells were set up with irradiated P815 (DBA/2 mastocytoma) stimulating cells and pure interleukin 2 obtained by recombinant DNA technology (rIL 2). Proliferation and generation of antigen‐specific cytolytic activity were observed to be both antigen and IL2‐dependent in such microcultures. Furthermore, P815 stimulating cells could be replaced by 5 other H‐2d cell lines of differing tissue origin. In limiting dilution studies, 1–2% of Lyt‐2+ CTL‐P (contaminated by < 0.2% macrophages) could be induced to grow and express cytolytic activity in the presence of irradiated P81S and rIL 2. Taken together, these data indicate that neither accessory cells nor differentiation factors (other than IL 2) are absolutely required for alloantigen‐induced growth and differentiation of CTL‐P.
A cell surface marker of thymus‐dependent lymphocytes in Xenopus laevis is identifiable by mouse monoclonal antibody
Authors: Nagata Saburo
Published: February 2007

A mouse monoclonal antibody (mAb), named XT‐1 (IgG2b,λ), was prepared against J strain Xenopus laevis thymocytes. The determinant recognized by this mAb (XT‐1 determinant) was expressed by 92–98% thymocytes and 22–37% splenic lymphocytes from intact J strain frogs and larvae, as analyzed by flow cytofluorometry. The XT‐1 determinant was also expressed by 20–30% peripheral blood lymphocytes and 5–11% bone marrow lymphocytes from adult, and 11–17% liver lymphocytes from larval J strain Xenopus. Early larval thymectomy depleted XT‐1‐positive cells in the spleen to less than 2% of the total lymphocyte population. Double immunofluorescence experiments revealed that XT‐1+ lymphocytes in the spleen are surface IgM−. The strain distribution study on the expression of XT‐1 determinant suggests the allelic polymorphism of the XT‐1 determinant. The surface antigen identified by the present XT‐1 mAb may provide an important marker for lymphocytes in thymus‐dependent lineage in Xenopus.
Antigen‐specific T cell suppressor factor (TsF): isolation of a cDNA clone encoding for a functional polypeptide chain of phosphorylcholine‐specific TsF
Authors: Sugimura Kazuhisa , Yamasaki Noriyuki , Matsuura Makiko , Watanabe Takeshi
Published: February 2007

A cDNA library of phosphorylcholine (PC)‐specific suppressor T hybridoma, 29‐C‐6, was constructed. By differential colony hybridization, 68 colonies were selected which hybridized with mRNA probes of two PC‐specific suppressor T hybridomas, 29‐C‐6 and 09‐M‐24–8, but not with those of BW5147. A hybridization translation assay revealed that only one combination of translation products of cDNA clones, p6–1 and p6–5, showed strong PC‐T cell suppressor factor (TsF) activity. Sequence analysis showed that p6–5 contained a specific cDNA sequence of about 800 base pairs (bp) while p6–1 had a 190 bp poly(A) sequence insert.

When total poly(A)+RNA of 29‐C‐6 was hybridized with a p6–1 filter alone the recovered mRNA was capable of producing PC‐TsF. However, when the total poly‐(A)+RNA was hybridized with a p6–1 filter combined with a p6–5 filter, the mRNA eluted from the p6–1 filter was not able to produce PC‐TsF, suggesting that the depletion of p6–5 specific mRNA from p6–1‐binding poly(A)+RNA led to a complete abolishment of the capability to produce PC‐TsF.

Furthermore, p6–5 hybridizing mRNA could successfully restore the p6–1‐binding poly(A)+RNA depleted of p6–5‐specific mRNA, and translation products of both RNA mixtures showed strong PC‐TsF activity. These results suggest that PC‐TsF is not a single polypeptide chain, but is composed of at least two distinct polypeptide chains, and also that p6–5 contains a cDNA sequence encoding for one of the polypeptide chains composing the PC‐TsF molecule.
Hepatobiliary transport of plasma IgA in the mouse: contribution to clearance of intravascular IgA
Authors: Delacroix Dominique Léon , Malburny Geneviève Nicole , Vaerman Jean‐Pierre
Published: February 2007

Labeled monomeric and polymeric (pIgA) mouse monoclonal IgA were injected intravenously into mice which were either sequentially bled for plasma turnover studies of IgA, or cannulated at their common bile duct, with excluded gallbladder, for quantitation of plasma‐to‐bile transport of pIgA. Our data show that mice do display a relatively high rate of biliary transport of plasma pIgA (22–28% of the injected 125I‐labeled pIgA over 3 h), which accounts for ∼90% of the total amount of pIg A (8.8 mg/kg/day) daily delivered by hepatic bile into the duodenal fluid of this species. However, in mice the absolute biliary output of pIgA does not exceed that of IgG (9.5 mg/kg/day) and the kinetics of the hepatobiliary transport of plasma PIgA appear to be slower than in the rat. Furthermore, as plasma survival studies of 125I‐labeled pIg A yielded a plasma turnover of pIgA averaging 20.6 mg/kg/day, it can be approximated that the hepatobiliary pathway contributes for only 38% to the elimination of intravascular pIgA from mouse plasma, a figure to be compared to 89.8% in the rat and ∼ 8.9% in man. We conclude that internal catabolism plays a dominant role in the clearance of intravascular pIgA in the mouse which appears as a model intermediate between rats and humans. Supporting this conclusion, serum pIgA two days after common bile duct ligation in 6 mice was increased by 2.5‐fold vs. > 14‐fold in ligated rats and 1.1‐fold in humans with complete biliary obstruction.
Antigens apparently nonimmunogenic for xid/Y mice cause the development of specific splenic plasmablasts and of fusion partners for SP2 cells giving hybridomas that secrete antibodies
Authors: Ohriner William D. , Cebra John J.
Published: February 2007

Although xid/Y mice fail to make a detectable primary antibody response to a variety of antigens such as Type III pneumococcal capsular polysaccharide (SIII), 2,4,6‐trinitrophenyl (TNP)‐Ficoll, pneumococcal C carbohydrate, group A streptococcal vaccine and several kinds of related antigenic determinants such as phosphorylcholine (PC) and N‐acetyl‐glucosaminyl (GlcNAc), even when the latter are coupled to hemocyanin (Hy), they do show: (a) an antigen‐dependent development of splenic B cells which can act as successful, productive fusion partners for SP2 cells giving hybridomas making monoclonal anti‐SIII, anti‐PC, anti‐GlcNAc, anti‐TNP, etc., and (b) an antigen‐dependent appearance of antigen‐binding plasmablasts in their spleens. The frequencies of specific B cells arising in xid/Y males with either of these properties are of the same order of magnitude as those found in immunocompetent xid/Y female littermates. Further, both PC‐Hy and GlcNAc‐Hy prime xid/Y and xid/X mice for quantitatively and qualitatively similar secondary responses. All three of these expressions of a specific, primary response occur in xid/Y mice in the absence of any rise in circulating antibodies.

The properties of successful, productive normal fusion partners leading to secretory hybridoma lines are unknown. Thus we cannot decide whether the antigen‐binding plasmablasts that arise in xid/Y mice can also play the role of productive fusion partners. Neither do we know whether the development of specific IgM and IgG3 plasmablasts in xid/Y mice after antigen stimulation is an abnormality reflecting the xid mutation. It cannot be excluded that the development of productive fusion partners, of nonsecretory plasmablasts and of memory cells are all interrelated and reflect a process that also normally occurs in xid/Y, X/X and X/Y mice following similar immunization regimens. It is tempting to speculate that such cells initially responding may lag in the development of normal secretory mechanisms and that the “transformed” fusion partner may complement this deficiency.
Ultrastructure of human C4‐binding protein: proposition for a new model
Authors: Villiers Marie‐Bernadette , Thielens Nicole M. , Villiers Christian L. , Colomb Maurice G.
Published: February 2007

The structure of human C4‐binding protein (C4bp), a regulatory factor of the classical C3 convertase of complement, has been under investigation for several years, but remains poorly understood. For example, the number of subunits in the C4bp molecule has not been established. In this report, we use two different techniques (partial reduction and electron microscopy) to clarify the structure of the C4bp. Our results lead us to propose a structural model which is quite different to that suggested before, i.e. the C4bp molecule appears to be a decamer. In addition to the disulfide bonds which link each subunit to another, a second disulfide interaction leads to the association of the subunits in pairs. Each pair of subunits appears as a filament ending in a globular head at the N‐terminal extremity. The pairs of subunits join to form a conical central domain (at the C‐terminal extremity) linked by disulfide bonds. The proposed pentameric shape of the C4bp is consistent with the stoichiometry of the C4b‐C4bp interactions. The proposed model indicates an overall structural homology between C4bp and other binding proteins.
Antibody density on rat red cells determines the rate of activation of the complement component Cl
Authors: Hughes‐Jones Nevin C. , Gorick Barbara D. , Howard Jonathan C. , Feinstein Arnold
Published: February 2007

It is a common observation that there is variability in the rate of activation of C1, the first component of complement, when bound to immune complexes. The cause of this variation has been investigated with experiments designed to assess separately the effect of antibody, antigen and C1 density. Using 125I‐labeled C1 and a rat monoclonal antibody specific for the class I antigen, it has been found that the rate of activation is primarily dependent on antibody density on the cell surface and not on antigen or C1 density. This finding supports the suggestion that direct contact between the Clr2Cls2subcomponent of C1 and antibody may be required for potentiation of C1 activation.
Modulation of complement receptors of a human monocyte cell line, U‐937, during incubation with phorbol myristate acetate: expression of an iC3b‐specific receptor (CR3)
Authors: Gilbert Danièle , Peulve Pascal , Daveau Maryvonne , Ripoche Jean , Fontaine Marc
Published: February 2007

The human monocyte line, U‐937, derived from an individual with histiocytic lymphoma was studied for the expression of surface C3 receptors, after cultivation in the presence of phorbol myristate acetate (PMA) or T lymphocyte‐conditioned medium. Receptors were detected by using EAC4b, EAC3b, EC3b, EAC3bi and EAC3d intermediates. U‐937 cells, in exponential growth phase, poorly bound the intermediates; after exposure to PMA or T lymphocyte‐conditioned medium, U‐937 cells strongly bound both EAC3b and EAC3bi since about 50% of cells rosetted with these intermediates. This binding was totally inhibited by EDTA and by Mac‐1 monoclonal antibody, suggesting the presence of only CR3 receptor types on these cells. Although U‐937 cells formed rosettes with EACSb, there was no evidence for the presence of CR1 receptors since no rosette was observed either with EAC4b or with EC3b intermediates (EC3b were prepared by coupling purified C3b to erythrocytes with N‐succinimidyl 3‐(2‐pyridyldithio)propionate. As small amounts of factor H were present on EAC3b intermediates, incubation of EAC3b with U‐937 cells induced their transformation into EAC3bi and their binding to CR3. Moreover, U‐937 cells did not promote the cleavage of C3b in the presence of factor I alone, suggesting that these cells did not bear a sufficient amount of functionally active CR1. These results demonstrated that U‐937 cells predominantly expressed CR3. The study of the kinetics of EAC3bi rosette formation demonstrated that CR3 expression is closely related to PMA activation. We suggest that CR3 activity could result from a phosphorylation of existing receptors.
Further characterization and subcellular localization of Sm and Ul ribonucleoprotein antigens
Authors: Habets Winand J. , Berden Jo H. M. , Hoch Sallie O. , van Venrooij Walther J.
Published: February 2007

Sera from patients with systemic autoimmune diseases often contain antibodies against small nuclear ribonucleoprotein (snRNP) particles. Anti‐Sm antibodies react with the entire set of U1, U2, U4, U5 and U6 (Ul‐U6) RNP particles whereas anti‐(U1)RNP sera specifically recognize particles containing U1 RNA. Here we performed semi‐quantitative immunoblotting using 16 human anti‐Sm, 15 human anti‐(U1)RNP sera and two mouse monoclonal antibodies to establish which snRNA‐associated proteins carry antigenic determinants. Almost every (15/16) human anti‐Sm sera recognized epitopes present on a 28‐kDa (B/B') protein doublet and on a 16‐kDa (D) polypeptide. Nine anti‐(U1)RNP sera also recognized the B/B' doublet, but in all cases a much stronger reaction was observed with one or more of the specifically U1 RNA‐associated 70 kDa, A or C antigens. With affinity‐purified antibody fractions eluted from individual antigen bands on nitrocellulose blots it is shown that the anti‐Sm‐reactive polypeptides B/B' and D contain common epitopes. We also report the finding of one human anti‐Sm serum with exclusive specificity for the B/B' doublet and a mouse monoclonal anti‐Sm antibody recognizing only the D protein, indicating that these antigens also carry unique epitopes. In immunoprecipitation assays, purified anti‐B/B' and ‐D antibodies react with (Ul‐U6) RNP while purified anti‐70 kDa, anti‐A and anti‐C antibodies precipitate exclusively U1 RNP particles. Finally, we established the subcellular localization of Sm and U1 RNP antigens using a biochemical cell fractionation procedure. Part of the 70 kDa and BIB' antigens were found in a nuclease and high salt‐resistant nuclear substructure, usually referred to as nuclear matrix, while the A and D antigens could be extracted completely from HeLa nuclei by ribonuclease treatment and subsequent high salt extraction.
Ontogenic development of “natural” and induced plaque‐forming cell isotypes in normal mice
Authors: Bjorklund Mariana , Pettersson Sven , Coutinho Antonio
Published: February 2007

The numbers of cells and background plaque‐forming cells (PFC) in the spleen of C3H/HeJ mice increase exponentially during the first 2 weeks after birth, but much slower in bone marrow (BM). IgGl and IgG2a PFC are the first non‐IgM PFC detectable, while IgG3 and IgA PFC appear only around weaning. Adult‐type PFC numbers and isotype pattern are present in spleen and BM at 4 and 15 weeks, respectively. Neonatal splenic C3H/Tif B cells produce non‐IgM Ig classes in vitro in response to polyclonal activation by lipopolysaccharide or by helper T cells. These responses are of low magnitude during the first 2 weeks of life, but both secreted and membrane‐bound IgG1 and IgG3 isotypes are detectable already a few days after birth, in a pattern that is identical to that typical of T cell‐dependent or independent responses of adult cells. These results indicate full maturity of B cells in “switch” abilities already from birth, in spite of a general deficiency in terminal maturation. In addition, they demonstrate the complexity of isotype regulation in “background” antibody production in vivo.
The limited immunocompetence of thymocytes within murine thymic nurse cells
Authors: Andrews Paul , Boyd Richard L. , Shortman Ken
Published: February 2007

Thymic nurse cells, cortical epithelial cells enclosing 20–200 lymphocytes, were prepared from mouse thymus by enzyme digestion and repetitive sedimentation. Individual nurse cells were then isolated free of any exogenous thymocytes by micromanipulation, and the endogeneous thymocytes released from inside the nurse cells by a brief period of culture. The thymocytes from within individual nurse cells were tested, at the one cell/well level, for their capacity to proliferate in high cloning efficiency mitogen‐stimulated limiting dilution cultures. The resultant clones were tested for their cytolytic capacity in a lectin‐mediated isotype‐release assay. Most intra‐nurse cell thymocytes were unresponsive, like typical cortical thymocytes, but an average of 1/30, or around 2–6 lymphocytes/nurse cell, were able to proliferate in response to concanavalin A. The clones produced were of a relatively small size, similar to those characteristic of helper‐lineage T cells. No cytolytic clones at all were obtained, despite stringent positive controls showing an efficient cytolytic response from known sources of cytolytic precursor cells. This finding disagrees with earlier studies on nurse cell lymphocytes, where there may have been a possibility of contamination with exogenous thymocytes. These results suggest either that the nurse cell represents a selective environment for helper‐lineage T cell differentiation, or that further steps after the nurse cell stage are needed to produce mature cytolytic‐lineage T cells.
Early events during primary activation of T cells: antigen receptor cross‐linking and interleukin 1 initiate proliferative response of human T cells
Authors: Scheurich Peter , Ücer Ugur , Wrann Michael , Pfizenmaier Klaus
Published: February 2007

To study early events during primary activation of human T cells, a simple method was developed which simultaneously allows positive selection of T cells from peripheral blood lymphocytes (PBL) and their polyclonal, antigen receptor‐mediated stimulation with anti‐T3 monoclonal antibodies. In the absence of accessory cells, T cells activated with matrix‐bound OKT3 express high levels of the Tac antigen within 15 h and produce interleukin 2 (IL 2). Tac expression was further enhanced by addition of exogenous IL 2. However, under these conditions purified T cells were unable to mount a proliferative response, whereas unfractionated PBL proliferated already after 24 h of culture. This unresponsiveness of purified T cells could be overcome by either re‐addition of low numbers of autologous accessory cells or semipurified human IL 1. As IL 1 had no significant effect on Tac expression of T3‐stimulated T cells, we conclude from these data that IL 1 exerts in addition to its influence on IL 2 production an effect, which allows antigen receptor‐triggered T cells to enter the cell cycle.
Trypanosoma cruzi: modulation of parasite‐cell interaction by plasma fibronectin
Authors: Ouaissi Mohamed Ali , Cornette Jocelyne , Capron André
Published: February 2007

Treatment of either rat peritoneal macrophages (RPM), cloned 3T3 fibroblasts (3T3FR) or Trypanosoma cruzi trypomastigote culture forms with human plasma fibronectin (huFN) enhanced their association with the untreated counterpart and this related to the concentration of huFN used. When treatment was performed at 4°C, the enhancing effect of huFN on parasite‐cell interaction was greater than that observed at 37 °C. This observation could be related to the indirect immunofluorescence antibody assay showing that a significant increase of fibronectin staining was observed on the cell and parasite surfaces upon incubation with huFN and that the extent of fibronectin staining was greater at 4°C. Incubation of huFN‐treated or nontreated parasites or cells with anti‐huFN antibodies exerted an inhibitory effect on the parasite‐cell association. The region of fibronectin that interacts with the trypomastigote surface is unknown. Inhibition experiments suggested that the domain of fibronectin which interacts with parasite surface receptors would probably be localized close to the NH2‐terminal region of the molecule. Taken together, these results suggest that fibronectin may play a role in the binding of parasites to the vertebrate host cell surface.
Nude mice are nonpermissive towards the anti‐dextran response of congenic cells
Authors: Weiler Ivan Jeanne , Sprenger Renate , Weiler Eberhardt
Published: February 2007

Nude mice bearing allotype Ighb on a BALB/c genetic background (= CB nu/nu) are nonresponders to α(1 → 3)dextran (Dex), in contrast to BALB/c or BALB/c nu/nu. Although CB nu/nu mice accept transplants of congenic BALB/c, or BALB nu/nu lymphocytes, as shown by the expression of donor allotype Igha, they are not permissive for a primary anti‐Dex response by the grafted cells. BALB/c or BALB nu/nu cells, however, give a strong anti‐Dex response when grafted onto irradiated CB nu/nu or CB23 (Ighb) euthymic mice.

A thymus‐independent, radiation‐sensitive suppressor cell population is postulated, which specifically hinders the anti‐Dex response, and which is exhibited by strains bearing that portion of chromosome 12 which codes for CH allotype Ighb, not containing the germ‐line anti‐Dex V/D genes. The suppressive action of Ighb lymphocytes could be demonstrated directly in staggered co‐transfer experiments.
The effects of stress in normal and adrenalectomized mice
Authors: Rocha Benedita
Published: February 2007

Many of the present concepts in lymphocyte physiology were established using experimental protocols involving surgery in cortico‐sensitive rodents. In the present report we demonstrate that commonly used operative procedures in mice result in a depletion of 50‐90% of cells from primary or secondary lymphoid organs 24 to 48 h post‐ surgery. Adrenalectomy, by itself, induces considerable depletion, and does not abolish the effects of stress in lymphocyte populations. These findings indicate that questions concerning the dynamics of production renewal rate and life‐span of lymphocytes cannot be investigated by approaches involving surgery in the mouse.
VH‐gene expression in murine lipopolysaccharide blasts distributes over the nine known VH‐gene groups and may be random
Authors: Dildrop Renate , Krawinkel Ulrich , Winter Ekkehard , Rajewsky Klaus
Published: February 2007

VH‐gene expression in hybridomas derived from lipopolysaccharide‐activated B cells was analyzed. Isolated cytoplasmic RNA was hybridized to probes representing the 9 known VH‐gene groups or subjected to mRNA sequencing. In the collection of hybridomas VH genes of all 9 groups are expressed at frequencies which in most correlate reasonably well with the relative complexities of the groups. In 51 out of 54 RNA samples VH‐gene transcripts could be identified and corresponded to one of the known VH‐gene groups. It therefore appears that the latter essentially represent the Vn‐gene cluster of the mouse.
Synergy of B cell growth factor and interleukin 2 in the proliferation of activated human B cells
Authors: Romagnani Sergio , Giudizi Grazia M. , Maggi Enrico , Almerigogna Fabio , Biagiotti Roberta , Delprete Gianfranco , Mazzetti Marcello , Aiessi Anna , Vercelli Donata , Ricci Mario
Published: February 2007

The activity of purified interleukin 2 (IL2), obtained by the recombinant DNA technology, on the proliferative response of human B cells stimulated with low concentrations of anti‐μ antibody was investigated. Recombinant IL2 was capable of augmenting the proliferative response of anti‐μ‐activated B cells and the T cell activation (Tac) antigen was expressed on a substantial proportion of normal B cells stimulated with anti‐μ antibody. However, crude supernatants from protein A‐stimulated peripheral blood mononuclear cells, which were found to possess both IL2 and B cell growth factor (BCGF) activities, maintained the ability to promote proliferation of anti‐μ‐ activated B cells after depletion of IL2. In addition, supernatants from some T cell clones, apparently free of IL2 activity, displayed strong BCGF activity in the costimulation assay with anti‐μ antibody. This BCGF activity was found in 25 kDa fractions by gel filtration and it was unaffected by addition to the cultures of anti‐Tac antibody, which consistently inhibited the B cell proliferative response promoted by recombinant IL2.

The proliferative response of anti‐μ‐activated B cells to clonal, IL2‐free supernatants containing BCGF and recombinant IL2 present together from the beginning of culture was close to the sum of responses to the two stimulants, separately. In addition, the presence of clonal supernatant containing BCGF from the beginning of culture had a synergistic effect in the response of activated B cells to the subsequent addition of IL2, whereas the initial presence of IL2 had no such an effect on the reactivity of anti‐μ‐stimulated B cells to the late addition of clonal supernatant containing BCGF. The synergistic effect of BCGF in the IL2‐promoted B cell proliferation was probably the result of the recruitment of a greater number of IL2‐reactive B cells. In fact, the number of Tac‐positive cells was significantly higher in 36‐h cultures established in the presence of anti‐μ antibody plus clonal supernatant containing BCGF than in cultures stimulated with anti‐μ antibody alone.

Taken together, these data indicate that anti‐μ antibody promotes the expression by normal human B cells of distinct receptors for IL2 and a BCGF distinct from IL2. They also suggest that BCGF can exert a synergistic effect in the IL2‐promoted proliferation of activated B cells.