To investigate the role of T cell differentiation antigens in autologous mixed lymphocyte reactions (AMLR), anti-T3, anti-T4 and anti-T8 antibodies were added to AMLR cultures separately, and examined for their capacity to modulate the reactions. Both anti-T3 and anti-T4 antibodies manifested profound inhibitory effects on AMLR-induced proliferative responses, whereas anti-T8 antibody did not. We next examined the precise mechanisms by which anti-T3 and anti-T4 antibodies interfered with AMLR-induced proliferation. Our overall results indicate that anti-T3 antibody in no way inhibits the expression of interleukin 2 (IL 2) receptors on the responding T-cells in AMLR cultures, but markedly inhibits IL 2 production during the course of the AMLR culture. The reverse is true for anti-T4 antibody. Taken together, these data provide strong evidence that T3 antigen may be involved in IL 2 production processes in the AMLR and that T4 antigen may play an important role in the processes of IL 2 receptor expression on responder T cells in the reactions.
