title: C-reactive protein antigenicity on the surface of human lymphocytes.
abstract: We reported previously that C-reactive protein (CRP), when complexed to a multivalent binding specificity, can bind to a subset of lymphocytes that bear the IgG Fc receptor. Recently we showed that anti-CRP plus complement depletes natural killer function. We now show the detection of CRP on the surface (S-CRP) of a small percentage of PBL and on a minor population of phagocytic mononuclear cells. S-CRP is not detectable by direct immunofluorescence, but is readily discernible by using more sensitive techniques such as biotinylated anti-CRP with fluorescent avidin or indirect immunofluorescence with monoclonal anti-CRP. S-CRP is expressed in the absence of calcium, whereas the binding of complexed CRP is calcium dependent. S-CRP does not appear to be the exclusive binding site for CRP-CPS because anti-CRP does not block the binding of complexed CRP. Both the binding site for complexed CRP and S-CRP can be capped off; however, the kinetics of capping of these two surface molecules is different. Cells binding complexed CRP are OKT11-, whereas a significant number of PBL bearing S-CRP are OKT11+. Therefore cells bearing S-CRP appear to be a separate population from those that bind complexed CRP. These studies establish the presence of S-CRP on a subpopulation of lymphocytes, define conditions required for its detection, and speak to certain of the relationships between S-CRP and the binding site of CRP-CPS complexes.
mesh_terms: D000911:Antibodies, Monoclonal / Q000276:immunology; D000954:Antigens, Surface / Q000032:analysis* / Q000276:immunology; D001665:Binding Sites; D001667:Binding, Competitive; D002097:C-Reactive Protein / Q000276:immunology* / Q000378:metabolism; D002118:Calcium / Q000097:blood; D005455:Fluorescent Antibody Technique; D006801:Humans; D007106:Immune Sera / Q000494:pharmacology; D007152:Immunologic Capping; D008212:Lymphocyte Depletion; D008214:Lymphocytes / Q000276:immunology*; D011135:Polysaccharides, Bacterial / Q000378:metabolism
chemical_list: D000911:Antibodies, Monoclonal; D000954:Antigens, Surface; D007106:Immune Sera; D011135:Polysaccharides, Bacterial; C027158:polysaccharide C-substance (Streptococcus); D002097:C-Reactive Protein; D002118:Calcium