Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P00790 (PGA)
 2,475 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Several mouse monoclonal IgG antibodies (AB1, AB2, AB3, and AB5) were developed that reacted with a 140,000 mol wt glycoprotein on the surface of cultured RAJI B lymphoid cells. The antibodies reacted with purified normal human peripheral blood B cells and CLL Ig+ B cells and showed specific germinal center and mantle zone staining in tissue sections of secondary lymphoid organs. Immunodepletion studies using 125I surface-labeled Raji cell membrane antigens demonstrated that the antigen identified by AB5 is the same 140,000 mol wt glycoprotein detected by anti-B2 that has recently been shown to react with the C3d fragment or CR2 receptor. (Iida et al: J Exp Med 158:1021, 1983). Addition of the AB series and anti-B2 monoclonal antibodies to cultures of purified human peripheral blood B cells resulted in the uptake of 3H-thymidine at two to six times background control levels provided that irradiated autologous T cells were added to the culture. Stimulation was not evoked by other monoclonal antibodies to B cell surface molecules (ie, B1, BA-1, BA-2, and HLA-DR). Pepsin-generated F(ab')2 fragments of anti-CR2 antibodies were essentially as effective as the intact IgG molecule in stimulating B cells. Induction of B cell proliferation by antibody binding to CR2 suggests that the C3d receptor may have an integral role in regulation of humoral immune response.
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PMID:Monoclonal antibodies to the 140,000 mol wt glycoprotein of B lymphocyte membranes (CR2 receptor) initiates proliferation of B cells in vitro. 293 Nov 42

We asked whether binding of human immunoglobulin (Ig)G antibody reacting with Raji cells could be distinguished from binding of IgG immune complexes. Using a standard Raji assay employing 125I-IgG goat anti-human Fc gamma, we found that digestion of Raji cells with pronase reduced by 95% their ability to bind complement-fixed aggregated human gamma globulin and complement-fixed tetanus toxoid-antitetanus toxin complexes. However, binding at 37 degrees C of IgG from the sera of 16 patients with systemic lupus erythematosus (SLE) to pronase-digested Raji cells was reduced much less consistently and extensively (9-100% reduction; mean reduction of 51%). In more detailed studies of two SLE sera, sucrose density gradient centrifugation showed that greater than 50% of the IgG binding to undigested Raji cells sedimented in the 7S region. Pepsin digestion of immunoglobulin fractions from four SLE sera caused a reduction in SLE IgG binding to undigested Raji cells when detected with 125I anti-Fc gamma, but an increase when binding was detected with 125I-anti-Fab, suggesting that substantial SLE IgG can bind through F(ab')2 regions. Binding of IgG from SLE sera was not directed at neoantigenic sites induced by pronase digestion because binding activity was adsorbed with undigested cells as readily as with digested cells. Moreover, sera from 10 SLE patients that had negative Raji assays contained no IgG that bound to pronase-digested Raji cells. We conclude that much of the IgG bound at 37 degrees C to Raji cells from the sera of many patients with SLE does not represent immune complexes but is probably antibody directed toward sites on the Raji cell.
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PMID:Raji cell assay for immune complexes. Evidence for detection of Raji-directed immunoglobulin G antibody in sera from patients with systemic lupus erythematosus. 699 84