Effect of verapamil on T-lymphocyte activation in vitro.

Verapamil, a calcium-inhibitory drug, was found to inhibit T-lymphocyte proliferation in mixed lymphocyte culture and the proliferative response to phytohaemagglutinin and mumps antigen. It also inhibited production of interleukin 2 (IL-2). To exert inhibition, verapamil had to be added early in the culture period. Verapamil also had a relatively small inhibitory effect on IL-2-dependent growth. The effects were clearly seen only at concentrations exceeding the therapeutic serum level of verapamil.