title: Blocking and redistribution ("capping") of antigen receptors on T and B lymphocytes by anti-immunoglobulin antibody.
abstract: Antigen-binding T and B lymphocytes were studied by combined autoradiography and immunofluorescence; mouse spleen lymphocytes binding the antigens, [(125)I]MSH or [(125)I]TIGAL, were incubated with rhodamine-labeled anti-Ig reagents or with a rhodamine-labeled IgG fraction of anti-theta serum. B cells were identified as Ig+ or theta-, T cells as Ig- or theta+. It was found that: (a) 20% (1-2 mo after priming) to 30% (3.5-4 mo after priming) of the antigen-binding cells were T cells. (b) The range of antigen molecules bound by B and T cells was similar. (c) Binding of antigen to B and T cells was inhibited by polyvalent anti-Ig, anti-micro, or anti-L reagents. Binding to T cells was more readily inhibited than to B cells. Normal rabbit serum, antimouse lymphocyte serum, or anti-theta did not inhibit antigen binding. (d) When Ig at the surface of B cells was induced, by noninhibiting concentrations of anti-Ig reagents, to redistribute into polar caps and the cells subsequently exposed to [(125)I)antigen under noncapping conditions, the [(125)I]antigen silver grains were distributed in caps superimposed on the Ig fluorescent cap. Of crucial importance, antigen was found in cap in the same proportion of T cells as B cells. Significant capping of antigen receptors was not induced in B or T cells with normal rabbit serum or by anti-Ig reagents absorbed with mouse Ig. The main conclusions of this series of experiments using direct visualization of antigen-binding B and T lymphocytes is that T cells have antigen-specific receptors, probably of IgM nature, and that the number of these receptors appears to range in the order of thousands.
mesh_terms: D000818:Animals; D000888:Antibodies, Anti-Idiotypic; D000918:Antibody Specificity; D000961:Antilymphocyte Serum; D001345:Autoradiography; D001402:B-Lymphocytes / Q000276:immunology*; D001666:Binding Sites, Antibody; D001921:Brain / Q000276:immunology; D005455:Fluorescent Antibody Technique; D006433:Hemocyanins; D007106:Immune Sera; D007140:Immunoglobulin Fab Fragments; D007074:Immunoglobulin G; D007136:Immunoglobulins; D007456:Iodine Isotopes; D051379:Mice; D008806:Mice, Inbred AKR; D008809:Mice, Inbred C3H; D009194:Myeloma Proteins; D010455:Peptides; D011817:Rabbits / Q000276:immunology; D013601:T-Lymphocytes / Q000276:immunology*
chemical_list: D000888:Antibodies, Anti-Idiotypic; D000961:Antilymphocyte Serum; D007106:Immune Sera; D007140:Immunoglobulin Fab Fragments; D007074:Immunoglobulin G; D007136:Immunoglobulins; D007456:Iodine Isotopes; D009194:Myeloma Proteins; D010455:Peptides; D006433:Hemocyanins