bluuebunny/crossref_metadata_2025_split huggingface dataset:
Expression of complement factor H on the cell surface of the human monocytic cell line U937
Authors: Malhotra Vivek , Sim Robert B. 
Published: February 2007

AbstractBinding assays and immunocytochemical staining with monoclonal antibodies against the human serum complement protein factor H indicate that factor H antigen is present on the surface of more than 95% of the cells of the human monocytic cell line U937. The antigen is uniformly distributed and there are 10000–15 000 copies/cell. Factor H antigen is strongly associated with the cell surface and is not removed by hypotonic or hypertonic washes. Factor H antigen has been isolated from surface radioiodinated and 35S biosynthetically labeled cells using polyclonal anti‐factor H‐Sepharose columns. The antigen is indistinguishable from serum factor H in molecular weight. Secretion of factor H by U937 cells was not detected using sensitive tests in which factor H secretion by monocytes was apparent. Phorbol myristate acetate stimulation of the cells had no effect on the average number of factor H molecules expressed. We conclude that factor H is synthesized by U937 cells, but is not secreted, and remains strongly associated with the cell surface. The surface‐bound factor H may function as a C3b receptor.
Ontogenic studies on the appearance of two classes of immunoglobulin‐forming cells in the spleen of the Aleutian skate, Bathyraja aleutica, a cartilaginous fish
Authors: Kobayashi Kunihiko , Tomonaga Susumu , Teshima Kazuyuki , Kajii Tadashi 
Published: February 2007

AbstractWe identified the presence in the Aleutian skate, Bathyraja aleutica, of two classes of immunoglobulins (Ig), a high molecular weight Ig analogous to mammalian IgM and a low molecular weight Ig, similarly to the spiny rasp skate, Raja kenojei, (Kobayashi, K. et al., Mol. Immunol. 1984. 22: 397), using an immunological cross‐reaction with the specific antisera to the spiny rasp skate Ig components. The antigenic similarity of the heavy chains of the Ig of the Aleutian skate and those of the spiny rasp skate was less than that between their light chains. Two types of Ig‐producing cells, one producing the high molecular weight and the other forming the low molecular weight Ig, were present in the spleen of embryos and adults in the Aleutian skate at a ratio of 5–6:4–5. The number of these Ig‐producing cells increased with advancing development of the embryos but was 1/20 to 1/50 of those of adults. Cells, each of which were capable of forming both classes of Ig, were found in the spleen of embryos but not in that of adults. These results suggested that the spleen of the Aleutian skate is the primary lymphoid organ for B lymphocyte differentiation and proliferation, possibly equivalent to the bursa of birds.
Bone marrow macrophages induced to antigen presentation by lymphokines interact selectively with distinct T cells
Authors: Fischer Hans‐Georg , Reske‐Kunz Angelika B. , Spaeth Eberhard , Rüde Erwin 
Published: February 2007

AbstractIn vitro matured bone marrow‐derived macrophages (BMMϕ), which represent a pure population of Mϕ, were shown to act as antigen‐presenting cells (APC) to the T cell clone ST2/K.9. This interaction was major histocompatibility complex restricted. Upon long‐term culture in macrophage colony‐stimulating factor, BMMϕ were activated for antigen presentation by a 48‐h pulse with lymphokine‐containing supernatant of concanavalin A‐stimulated rat spleen cells (Con A sup). The capacity of such activated Mϕ to function as APC decreased upon removal of Con A sup, and could be regenerated by a second pulse. This finding suggests that antigen presentation by mature Mϕ is a reversible function regulated by T cell factors. When the responsiveness of various T cell lines to antigen presented on BMMϕ or spleen cells was compared, distinct activation requirements were observed for different T cells since lymphokine‐activated BMMϕ were not capable of inducing antigen‐specific proliferation of all lines.
The ability of Ia and H‐2Kk‐bearing membranes to replace the antigen‐presenting cell in an H‐2Kkallogeneic cytotoxic T cell response
Authors: Weinberger Ofra , Herrmann Steven H. , Greenstein Julia L. , Mescher Matthew F. , Burakoff Steven J. 
Published: February 2007

AbstractInduction of an allogeneic cytotoxic T lymphocyte (CTL) response is dependent, in part, on uptake and processing of the class I alloantigen by antigen‐presenting cells and subsequent Ia‐restricted recognition of the alloantigen by helper T cells, resulting in lymphokine production. The nature of the antigen‐processing event has been investigated using reconstituted membranes to replace the antigen‐presenting cells in the generation of a secondary allogeneic CTL response. Membranes were isolated from an Iad‐positive antigen presenting B cell lymphoma (D2N), detergent solubilized and then reconstituted together with affinity‐purified H‐2Kk antigen in the presence of protease inhibitors. These reconstituted vesicles, containing both syngeneic Ia and alloantigen, were able to induce the helper T cell arm of the CTL response in cultures depleted of antigen‐presenting cells. A variety of control experiments provided strong evidence that the helper T cells recognized the H‐2Kk, probably in its native form, in an Ia‐restricted manner on the vesicles, while the pre‐CTL can directly recognize H‐2Kk. Recognition was only effective if both the Ia and alloantigen were inserted into the same membrane bilayer. The results strongly suggest that the obligatory antigen processing event required for helper T cell recognition of alloantigen is simply the insertion of the alloantigen into the same membrane bilayer as the syngeneic Ia restricting element.
Insulin‐specific T cell hybridomas derived from (H‐2b × H‐2k)F1 mice preferably employ F1unique restriction elements for antigen recognition
Authors: Reske‐Kunz Angelika B. , Rude Erwin 
Published: February 2007

AbstractT cell hybridomas of (B10 × B10.BR)F1 genotype with reactivity to bovine insulin (BI) were established to analyze the restriction and antigen fine specificity of (H‐2b × H‐2k)F1 T cells towards BI. Our data indicate a focusing of the response on two epitopes on the insulin molecule, the A chain loop determinant comprising amino acids A8 and A10, as well as the glutamic acid residue in position 4 of the A chain. Both were recognized either separately or in conjunction. Unexpectedly, the T cell hybridomas exhibited a marked preference for recognizing insulin in the context of F1‐unique restriction elements of A A type rather than parental high‐responder I‐Abmolecules. Analysis of the response of primed lymph node T cells of (B10 × B10.BR)F1 mice towards BI corroborated the finding of a preponderant corecognition of F1unique I‐A molecules.
The effects of cyclosporin on lymphocyte activation in a systemic graft‐vs.‐host reaction
Authors: Chisholm Patricia M. , Drayson Mark T. , Cox Josephine H. , Ford William L. 
Published: February 2007

AbstractWe have investigated the effects of cyclosporin (CsA) on each of three stages of lymphocyte activation in vivoviz. sequestration of alloantigen‐reactive lymphocytes from the circulation into the spleen and lymph nodes, blast transformation and induction of DNA synthesis in the activated cells and release of these cells and their progeny into the circulation. Parental strain lymphocytes injected i.v. into semiallogeneic rats and recovered from the thoracic duct within 36 h are profoundly unresponsive in a local graft‐vs.‐host assay to the alloantigens of the F1 hybrid but have normal activity against unrelated alloantigens (negative selection). CsA treatment of the F! hybrid recipients did not prevent this selective sequestration of antigen‐reactive cells. In the untreated FI hybrid, from 36 h after injection, large numbers of dividing blast cells were released into the lymph. These cells did not appear in the lymph of recipients treated with CsA. However, CsA did not prevent the activation of cells sequestered in the spleen or lymph nodes as assessed by [3H] thymidine incorporation and autoradiography. This unexpected finding suggests that CsA inhibits lymphocyte responses to alloantigens in vivo after DNA synthesis which is a later stage than the in vitro studies have shown.
Direct effect of interleukin 2 on the differentiation of human B cells which have not been preactivated in vitro
Authors: Bich‐Thuy LĚ Thi , Fauci Anthony S. 
Published: February 2007

AbstractUnfractionated as well as small and large human tonsillar B cells were found to differentiate in the presence of recombinant interleukin 2 (IL 2) without requiring an in vitro preactivation signal. These cell suspensions did not contain detectable T cells, monocytes or natural killer cells both at the initiation and the termination of cultures, and did not respond to the T cell‐dependent polyclonal B cell activator pokeweed mitogen. They contained very few Tac antigen‐bearing cells (less than 2.5%) at the beginning and at the termination of the cultures in the absence of IL 2. In the presence of IL 2, only a minimal increase in the number of Tac antigen‐bearing cells was noted. The observed differentiation was not due to the effects of contaminating T cells, since cultures purposely contaminated with up to 5% of T cells did not contain greater amounts of IgM, IgG or IgA than cultures without T cells added back. Furthermore, when T cells were present at a ratio of IT cell per 9 B cells, the production of IgM was decreased. Taken together, these data support the hypothesis that (a) B cell differentiation in response to IL 2 may occur in the absence of in vitro preactivation, and in this case cannot be related to the expression of Tac antigen on the B cell surface; (b) it is not due to helper effects of very low numbers of T cells which might contaminate the B cell suspensions; and (c) it most likely results from a direct effect of IL 2 on B cells themselves. The data also point out the fact that, in the presence of IL 2, T cells may trigger inhibitory effects on IL2‐induced B cell differentiation rather than provide helper signals.
Biochemical and functional characteristics of the human leukocyte membrane antigen family LFA‐1, Mo‐1 and p!50,95
Authors: Keizer Gerrit D. , Borst Jannie , Figdor Carl G. , Spits Hergen , Miedema Frank , Terhorst Cox , de Vries Jan E. 
Published: February 2007

AbstractThe human leukocyte function‐associated (LFA‐1) antigen, the monocyte differentiation antigen Mo‐1 which is characterized as the C3bi receptor and the glycoprotein p150,95 are characterized biochemically. Immunoprecipitations carried out with 6 different monoclonal antibodies (mAb) against LFA‐1 indicated that four mAb (SPV‐ L1, SPV‐L5, SPV‐L7 and SPV‐L11) were directed against the a chain, whereas mAb CLB54 and MHM‐23 were found to react with the common β chain of LFA‐1, Mo‐1 and p150,95. LFA‐1 and Mo‐1 expressed on KG‐1 cells or lymphocytes, monocytes and granulocytes from one donor were homogeneous. Interestingly the a chain of p150,95 showed heterogeneity. The molecular weight of the a chain expressed on monocytes was consistently higher than that of the α chain on granulocytes. The β subunits of LFA‐1 and Mo‐1 (as detected by mAb Bear‐1) are not only similar in molecular weight and isoelectric focusing patterns, but it is demonstrated here that they are also identically glycosylated and have similar protein backbones as judged by tryptic peptide mapping. In spite of their structural similarities, LFA‐1 and Mo‐1 differ completely in some of their biological functions. Anti‐LFA‐1 mAb strongly inhibited monocyte‐dependent T cell proliferation induced by tetanus toxoid or Helix pomatia hemocyanin and pokeweed mitogen‐driven specific antibody production in vitro, whereas the anti‐Mo‐1 antibody Bear‐1 was ineffective. These results suggest that the differences in these biological functions of LFA‐1 and Mo‐1 may be related to their different a subunits, which may recognize specific counter structures.
Biosynthesis of complement protein D by HepG2 cells: a comparison of D produced by HepG2 cells, U937 cells and blood monocytes
Authors: Barnum Scott R. , Volanakis John E. 
Published: February 2007

AbstractThe biosynthesis of complement protein D of the alternative pathway by HepG2 cells, a human hepatocyte cell line, was studied and compared to the biosynthesis of D by U937 cells and blood monocytes. Increasing amounts of antigenic D were detected in HepG2 cell culture supernatants by radioimmunoassay. The kinetics of D synthesis and secretion by HepG2 cells was followed in a pulse‐chase study using [35S]cysteine. As analyzed by sodium dodecyl sulfate‐polyacrylamide gel electrophoresis followed by autoradiography, only a single D band was seen intra‐ and extracellularly and both forms had the same apparent molecular weight as D synthesized by U937 cells or purified from serum. Treatment of HepG2 and U937 cells with canavanine, an arginine amino acid analog, to inhibit intracellular processing resulted in slight depression of the apparent molecular weight of D synthesized by these cells. D synthesized by blood monocytes had an apparent molecular weight similar to that synthesized by HepG2 and U937 cells, suggesting that these cell lines do not synthesize and process D differently than normal monocytes. The data demonstrate that the hepatocyte is a site of D synthesis and suggest that D is not synthesized as a precursor molecule.
Monoclonal antibody 9.3 and anti‐CD11 antibodies define reciprocal subsets of lymphocytes
Authors: Yamada Hironori , Martin Paul J. , Bean Michael A. , Braun Marcus P. , Beatty Patrick G. , Sadamoto Kenichiro , Hansen John A. 
Published: February 2007

AbstractWe have previously described antibody 9.3 which recognizes a 44‐kDa polypeptide designated Tp44 expressed on 70‐80% of peripheral blood T cells, including nearly all CD4+ cells and some CD8+ cells. Whereas the 9.3+ population contains helper cells, cytotoxic T cell precursors and cytotoxic T cell effectors, the 9.3− population has been reported in several models to contain precursors for suppressor cells. In this report, we demonstrate that 9.3− lymphocytes express CD11, an antigen which is also present on monocytes and granulocytes. Among lymphoid cells, Tp44 and CD 11 represent markers that identify reciprocal, nonoverlapping subsets, each of which contains both CD8+ cells and CD4+ cells. With Tp44 and CD11, and CD4 and CDS, the development and function of T cells can thus be examined within the framework of two distinct systems of reciprocally expressed antigens.
Distribution of class IIDQ antigens on normal and leukemic lymphoid cells
Authors: Fermand Jean‐Paul , Schmitt Christian , Brouet Jean‐Claude 
Published: February 2007

AbstractThe distribution of DQ as well as DR antigens was examined on lymphoid and monocytic cells at different stages of differentiation. In the B cell series, both immature and differentiating (under Staphylococcus aureus or pokeweed mitogen stimulation) B cells often lacked DQ molecules; among surface IgM+ and IgD+ cells, both DQ and DR molecules were detected except on cells from 30% of the lymphoid malignancies studied. T cells expressed DQ molecules only after stimulation; a DQ−DR+ phenotype was observed in a large number of cells after allogeneic stimulation, in certain antigen‐specific T cell lines as well as in T cell lymphomas, suggesting that class II antigens had a distinct pattern of regulation. In the monocytic lineage, DQ molecules were expressed by most lymph node monocytes and only a low percentage (20%) of circulating monocytes.
gp140, a C3b‐binding membrane component of lymphocytes, is the B cell C3dg/C3d receptor (CR2) and is distinct from the neutrophil C3dg receptor (CR4)
Authors: Frade Raymond , Myones Barry L. , Barel Monique , Krikorian Laure , Charriaut Christiane , Ross Gordon D. 
Published: February 2007

Abstractgp140, previously identified as a 140‐kDa C3b‐binding membrane glycoprotein present on Raji cell surface, was shown to be the C3dg/C3d receptor of B lymphocytes (CR2). Specific polyclonal anti‐gpl40, prepared by immunizing rabbits with this highly purified C3 receptor, blocked Raji cell rosettes with EC3b, EC3bi, EC3dg and EC3d, and also blocked normal lymphocyte rosettes with EC3dg and EC3d without affecting CR1 or CR3 activity. Moreover, a monoclonal anti‐C3 (C3b/#130), described by others as reacting with the d region highly expressed on ECSbi, EC3dg and EC3d and poorly exposed on EC3b, completely inhibited EC3bi, EC3dg and EC3d rosettes with Raji cells, but had no effect on EC3b rosettes. Treatment of Raji cells with rabbit anti‐gp140 blocked the uptake of three 125I‐labeled monoclonal antibodies anti‐B2, HB‐5 and OKB7 reported to react with C3d‐binding proteins, indicating that each of these monoclonal antibodies recognizes epitopes present on gp140.The neutrophil C3dg receptor was examined to determine its relationship to lymphocyte CR2. While neutrophil rosettes with EC3d were undetectable, a specificity for C3d was suggested by the inhibition of EC3dg rosettes by fluid phase C3d‐complexes bearing no detectable C3dg. However, such neutrophil EC3dg and EC3bi rosettes were not inhibited by rabbit anti‐gp140 nor an excess of anti‐CRl, anti‐CR2, and anti‐CR3. In addition, neutrophils did not bind 125I‐labeled anti‐gp140, anti‐B2, or HB‐5. Thus, the neutrophil C3dg receptor is distinct from gp140, the lymphocyte CR2, and should be designated CR4.
Epitope‐specific regulation of the T cell repertoire: carrier recognition in association with I‐E or I‐A does not influence the restriction of hapten‐specific T cells
Authors: Trannoy Emanuelle , Regnier Daniel , Campbell Helen , Seman Michel 
Published: February 2007

AbstractThe T cell repertoire of BALB/c mice contains clones capable of recognizing p‐azobenzenearsonate (ABA)‐tyrosine (Tyr) in association with both I‐A and I‐E‐encoded class II molecules. Immunization of BALB/c animals with ABA‐GAT (ter‐polymer of L‐Glu60‐L‐Ala30‐L‐Tyr10) or ABA‐GLT (terpolymer of L‐Glu51‐L‐Lys34‐L‐ Tyr15) instead of ABA‐Tyr reduces the secondary proliferative response to ABA‐Tyr in vitro. Limiting dilution experiments indicate that this situation corresponds to the recruitment of fewer ABA‐specific T cells in vivo. The same experiments, performed in A.TH mice, which are nonresponder to both GAT and GLT, demonstrate that the number of ABA‐specific T cells stimulated in vivo with ABA conjugates depends on the Ir gene‐controlled immunogenicity of the carrier rather than on the ABA epitope density on the immunogen. Although GAT is preferentially recognized in association with A, and GLT with E, ABA‐GAT and ABA‐GLT stimulate both A and E‐restricted ABA T cells in vivo and in vitro. The ABA‐Tyr‐specific T cell repertoire is not qualitatively affected by the carrier. This demonstrates that the inhibition of hapten‐specific T cell expression upon immunization with ABA conjugates does not result from a competition between hapten and carrier‐specific T cells for epitope recognition in association with the same la molecule on antigen‐presenting cells.
Immunologically discrete conformation isomers of I‐A locus‐equivalent class II molecules detected in Lewis rats
Authors: Reske Konrad , Weitzel Rainer 
Published: February 2007

AbstractMonoclonal antibodies MRC‐OX6 and MRC‐OX3 were used to define biosyntheti‐cally inter‐related subsets of I‐A‐equivalent class II molecules from Lewis rat spleen cells. MRC‐OX6 was shown to recognize specifically multiple forms of the class II molecule arising along its maturation pathway from the origin of polypeptide chain synthesis, the rough endoplasmatic reticulum, through the Golgi compartment to the plasma membrane. Three MRC‐OX6‐reactive polypeptide chain complexes were distinguished: (a) an early complex composed of immature components of the polymorphic α, β heterodimer in noncovalent association with immature proteins of the invariant γ‐chain group p40, p33 (γ), p28, p20; (b) a biosynthetic intermediate comprising the subunits α,β and γ all of them being extensively glycosylated and sialy‐lated. The latter constituent is referred to as p36; (c) a cell surface structure consisting of the mature α, β heterodimer devoid of the mature invariant chain p36. A two‐dimensional (2D) separation pattern exhibited by an MRC‐OX6‐specific immunoprecipitate from spleen cells labeled for 4 h represents a superposition of these three MRC‐OX6‐reactive polypeptide chain complexes. In contrast, MRC‐OX3 recognizes exclusively a fully mature aα,β heterodimer devoid of protein precursor forms and devoid of any invariant chains. Considering the previous observation that the respective α and β subunits of MRC‐OX6 and MRC‐OX3‐specific molecules comigrate on 2D O'Farrell gels combined with the data of this investigation, it is suggested that the mature MRC‐OX6‐specific α,β heterodimer and the mature MRC‐OX3‐specific α,β heterodimer originate from the same biosynthetic intermediate. We propose that before entering the plasma membrane an MRC‐OX6‐reactive molecule composed of fully glycosylated α,β and p36 releases its post‐translationally processed γ chain (p36), giving rise to two conformation isomers, one α,β heterodimer still being reactive with MRC‐OX6 and one α,β heterodimer which has lost the serologic MRC‐OX6 and gained the MRC‐OX3 specificity. Both α,β heterodimers are expressed on the cell surface as two distinct subsets of I‐A‐equivalent class II molecules.
Three distinct subpopulations of sheep T lymphocytes
Authors: Mackay Charles Reay , And Jillian Fay Maddox , Brandon Malcolm Roy 
Published: February 2007

AbstractMonoclonal antibodies reactive with distinct T lymphocyte subpopulations have been described in man, mouse and rat and structural analyses of these antigens have demonstrated a high degree of evolutionary conservation. This report describes the reactivity of three monoclonal antibodies (mAb), 19–19, αSBU‐T4 and αSBU‐T8, which define T cell subpopulations in the sheep. The mAb αSBU‐T4 and αSBU‐T8 define the sheep CD4 and CD8 molecules, respectively. These two antigens show similar tissue distributions, molecular weights and fluorescence‐activated cell sorter profiles to human, mouse and rat CD4 and CD8 molecules. The mAb 19–19 is reactive with a subpopulation of T lymphocytes which displays a tissue distribution unlike that reported for a T cell subset in any other species. 19–19 stains 7% of efferent lymph lymphocytes, 15% of peripheral blood lymphocytes but only 1–3% of lymph node lymphocytes. Two‐color immunofluorescence demonstrates that the 19–19+ T cell subset is SBU‐T4− and SBU‐T8−, and thus defines a third T cell subpopulation in sheep. Immunohistology on frozen lymph node tissue sections localizes 19–19 mAb‐reactive cells to the subcapsular region of the lymph node and lymph node trabeculae. Only 1% of thymocytes are 19–19+ and these cells are located mainly in the medulla and often arranged as foci around blood vessels. The 19–19 mAb immunoprecipitates from sheep lymphocytes an antigen with an apparent molecular mass of 215 kDa under both reducing and nonreducing conditions. It is concluded that αSBU‐T4 and αSBU‐T8 recognize the sheep homologues of the human T4 and T8 antigens, respectively, whereas 19–19 recognizes an antigen (termed SBU‐T19) which has not been reported in any other species.