The immunotoxicity of prenatal cocaine exposure was investigated using Sprague-Dawley rats and C57B1/6 mice. Pregnant animals were injected twice a day with cocaine or saline from gestation day 5 until the day before parturition. The immune system of the rat offspring was evaluated at 8 weeks of age by measuring the antibody response to SRBC (plaque assay and serum IgM), delayed-type hypersensitivity response to KLH, and lymphocyte subpopulations in the spleen and thymus using flow cytometry. The immune system of the mice offspring was evaluated at 4 weeks of age by measuring spleen cell proliferation in response to KLH, LPS, and alpha CD3 and IgG production to KLH. From the differences observed between cocaine exposed animals and controls, we conclude that prenatal cocaine exposure does not cause lasting detrimental effects on the immune system, but instead, may enhance. B-cell responsiveness. (C) 1997 Elsevier Science Ireland Ltd.