Inhibition of human lymphocyte responses by methylmethacrylate

The in vitro response of normal stimulated human peripheral blood lymphocytes to methylmethacrylate (MMA) was a dose related inhibition. Fifty per cent inhibition occurred at concentrations of 0.078-0.125%. MMA affected not only responses to soluble phytomitogens but also responses to specific antigens and allogeneic lymphocytes. Numbers of viable cells in cultures with and without mitogens and MMA were comparable at the beginning and end of experiments, excluding methacrylate-related cytotoxicity as the primary mechanism of inhibition of lymphocyte responses. Inhibition did not result from alteration of kinetics of lymphocyte responses. Inhibition was greatest when MMA was added during early phases of cellular activation. It also reduced the ability of T-lymphocytes to rosette with sheep erythrocytes. These data indicate that MMA causes noncytotoxic, incompletely reversible inhibition of nonspecific, specific, soluble, and insoluble stimulated lymphocyte responses and rosette formation in vitro.