Antigen-binding receptors on T cells from long-term MLR. evidence of binding sites for allogeneic and self-MHC products.
Antibody inhibition of radiolabelled stimulator membrane vesicle binding by T blasts activated in the mixed lymphocyte reaction (MLR) was used to identify responder-cell determinants involved in the binding phenomenon. Antisera or monoclonal antibodies against Thy-1, Lyt-1, Lyt-2 and Ly-6 antigens were not inhibitory. However, antibodies against heavy-chain V region (VH) determinants strongly inhibited vesicle binding by both primary and long-term MLR blasts. Anti-Ia (both alloantisera and monoclonal reagents) caused inhibition of antigen binding by primary MLR blasts only. T blasts from long-term MLR lines were neither Ia-positive, nor susceptible to blocking of antigen binding with anti-Ia. However, these cells were capable of specifically absorbing soluble syngeneic Ia material, with the concomitant appearance of vesicle-binding inhibition with anti-Ia sera. Acquisition of syngeneic Ia by T blasts was effectivelly blocked with the anti-VH reagent. Passively bound self-Ia did not interfere with vesicle binding in the absence of anti-Ia. These results strongly suggest the existance of specific self-Ia acceptor sites closely linked to the receptors for stimulator alloantigens on T cells proliferating in MLR. A receptor model based on these findings is briefly discussed.
D000818:Animals; D001665:Binding Sites; D000949:Histocompatibility Antigens Class II / Q000378:metabolism; D007135:Immunoglobulin Variable Region / Q000378:metabolism; D007519:Isoantigens / Q000378:metabolism*; D008213:Lymphocyte Activation; D007959:Lymphocyte Culture Test, Mixed; D008285:Major Histocompatibility Complex; D051379:Mice; D008954:Models, Biological; D011948:Receptors, Antigen, T-Cell
D000949:Histocompatibility Antigens Class II; D007135:Immunoglobulin Variable Region; D007519:Isoantigens; D011948:Receptors, Antigen, T-Cell