title: Regulation of antigen-induced lymphoproliferation by BSA gradient-separated T cell fractions.
abstract: Human T cells from 6 volunteers immunized with keyhole limpet hemocyanin (KLH) or tetanus toxoid were fractionated on bovine serum albumin (BSA) gradients. These T cell fractions were then recombined with autologous unseparated mononuclear cells or unseparated T cells to determine the effect of each fraction on the proliferative (DNA synthetic) response to the immunizing antigen. Using this separation technique, we were able to define 2 fractions of T cells of widely different densities that had a suppressive effect on the proliferative response to KLH of unfractionated T cells. The demonstration of suppressive activity was possible only if cells were tested within 8 wk of immunization with KLH. These suppressive T cell fractions differed not only in density but also in surface characteristics. Fraction 1 cells had a high proportion of Ia+ cells but no Fc receptors for IgG (FcRG-) were seen, whereas cells from fraction 4 (of higher density) were Ia- and were composed of 12.1 +/- 1.2% FcRG+ cells. this suppression was shown to be specific for the immunizing antigen. One individual who had been immunized with KLH for more than 1 yr in which suppression of KLH-induced proliferation was no longer demonstrable was given primary immunization to tetanus toxoid. Suppression could be demonstrated in fractions 1 and 4 specific for tetanus toxoid; there was no demonstrable effect of these T cell fractions on the response to KLH. We postulate that these are different functional populations of suppressor T cells that regulate antigen specific lymphoproliferation.
mesh_terms: D000818:Animals; D000941:Antigens; D002417:Cattle; D002469:Cell Separation; D002499:Centrifugation, Density Gradient; D000939:Epitopes; D006801:Humans; D007114:Immunization; D008213:Lymphocyte Activation; D012710:Serum Albumin, Bovine / Q000494:pharmacology*; D013601:T-Lymphocytes / Q000276:immunology; D050378:T-Lymphocytes, Regulatory / Q000276:immunology; D013997:Time Factors
chemical_list: D000941:Antigens; D000939:Epitopes; D012710:Serum Albumin, Bovine