[Effects of benzo(a)pyrene on the humoral immunity of mice exposed by single intraperitoneal injection].

Mice were exposed to benzo(a)pyrene at a dosage of 50, 100 and 200 micrograms/g by single intraperitoneal injection route. The control mice were given vehicle alone (olive oil). The mice were killed 5 days later. At above dosage, it was found the body weight, thymus and spleen weights, and the leukocyte count in peripheral blood were significantly reduced as compared to control. In the plaque forming cell (PFC) assay, it was also found the IgM antibody forming response to the thymus independent antigen (TNP-Ficoll) and the thymus dependent antigen (TNP-KLH) were inhibited about 57-94% and 58-80%, respectively, (P less than 0.05). The serum anti-TNP-Ficoll antibody titer was suppressed 46-98% and parallelled to the corresponding spleen PFC response. The results suggested the benzo(a)pyrene or its metabolites may directly affect the more matured B lymphocyte's function.