Nicotine suppresses the proliferative response of peripheral blood lymphocytes in rats

Nicotine, the psychoactive ingredient of cigarette smoke, alters lymphocyte function in vitro. However, unlike tobacco smoke, the immunologic effects of nicotine in vivo have not been determined. In the present study a single SC administration of 0.33, 0.66, or 1.32 mg/kg (free base) of nicotine bitartrate to male rats produced a dose‐dependent decrease in the in vitro proliferative response of blood lymphocytes to the T‐cell mitogen Con A when sampled 1 hr after nicotine administration. These results strongly suggest that acute nicotine exposure can induce immune perturbation in vivo. Nicotine also increased plasma corticosterone (CORT) and there was a substantial negative correlation (r = −.52) between CORT levels and the extent of proliferation (DPM) for the optimal Con A dose. The correlation between nicotine's immunologic and CORT effects is discussed within the context of several other potential mediators of nicotine's effects. © 1992 Wiley‐Liss, Inc.