Effect of Human Leukocyte Interferon on the Response of Lymphocytes to Mitogenic Stimuli In Vitro

Partially purified human leukocyte interferon suppressed the in vitro response of human lymphocytes to phytohaemagglutinin. concanavalin A, and purified protein derivative and also the mixed lymphocyte reaction. The inhibitory effect correlated with concentration and was detectable at 10 units/ml of culture medium. The activation of lymphocytes by pokeweed mitogen was affected by interferon only in very high concentrations The data presented are considered to be of clinical importance, since the serum interferon levels in patients receiving therapy with such preparations exceed the concentrations required for detection of in vitro inhibition of mitogenic stimuli.