Add to ORKGThe effects of in vitro recombinant interleukin-2 (IL-2) treatment on lymphocyte proliferation and Natural Killer (NK) cell activity inhibited by cocaine were examined. In lymphocytes activated by PHA (2mug/ml), cocaine induced a decrease of [H-3]-thymidine incorporation at the drug concentrations presented in the blood of addicts (0.1 mug/ml). This effect was not observed when IL-2 (500 U/ml) was present in the incubation medium. Interestingly, in non PHA-activated cells, cocaine had no effect on lymphoproliferative response to IL-2. Parallelly, in vitro addition of IL-2 (20, 200, 500 U/ml) promoted the reversal of the inhibition of NK cell cytotoxicity of spleen lymphocytes collected from cocaine-immunosuppressed mice. We conclude that IL...