The effect of benzo-pyrene on humoral antibody formation in vitro

The significance of chemical carcinogen-induced immunosuppression of the anti-sheep red blood cell response in C3H mice was investigated. The humoral immune response to a T-dependent antigen was simulated using a technique in which splenic lymphocytes were incubated in vitro (3). When the potent carcinogen benzo(a)pyrene (BP) was added to this system, the ability of these spleen cells to respond to a foreign cell, sheep red blood cells (SRBC), was greatly decreased. BP at concentrations as low as 10^-8 molar was capable of suppressing the immune response. Maximum inhibition, (app. 100%), was obtained at a concentration of aligned 4 x 10^-4 molar; this however, may have been partially due to the inherent toxicity of the BP. A characteristic dose response curve occurred in the range 10 - 10 molar; lower concentrations showed no inhibition or a slight enhancement of the plaque forming cell response (PFC). When the non-carcinogenic analog of benzo(a)pyrene, benzo(e) pyrene (B(e)P), was tested, no inhibition was seen in the range 10^-7 10^-5 molar. This supports the existing evidence that BP suppresses the immune system in mice (4,26).