AbstractThere is a high prevalence of cocaine abuse among Americans. There is an increasing concern over the rise of infectious diseases among individuals in this drug abuse population. This concern may be due, at least in part, to a direct effect of cocaine on the immune system. The present study investigated the effects of cocaine administration on optimal mitogen-induced proliferation in rats. Following cocaine administration, splenic lymphocytes were isolated and T-lymphocytes incubated with concanavalin A. When T-lymphocytes were isolated 30 minutes following cocaine administration, a significant enhancement of optimal mitogen-stimulated proliferation was observed at 0.1 mg/Kg cocaine. Enhancement of proliferation was seen 20 hours following cocaine administration at 0.1, 1.0 and 10 mg/Kg. However, these results were not statistically significant. Cocaine administered once daily for seven days had no effect on mitogen-induced proliferation. These results suggest that cocaine administration has a limited effect on optimal mitogen-stimulated proliferation.