Effect of Noncarcinogenic and Carcinogenic Hydrocarbons on Antibody-Forming Cells Measured at the Cellular Level In Vitro2

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Abstract
The number of antibody-forming cells in adult CBA male mice was determined in vitro by an agar plaque technique 5, 11, and 36 days after exposure of the host to carcinogenic or noncarcinogenic hydrocarbons. The number of plaque-forming spleen cells (PFC) was depressed, both totally per spleen and specifically within the spleen cell population, after the host had been exposed to the carcinogenic hydrocarbons benzo[a]pyrene (BaP), 7,12-dimethylbenz[a]anthracene (DMBA), or 3-methylcholanthrene (MCA). The noncarcinogenic hydrocarbons anthracene (Ae) and benzo[e]pyrene (BeP) had no such immunodepressive effect. 7-Methyldibenzanthracene (MDBA) had a slightly depressive effect on the number of PFC. BaP, DMBA, and MCA are all potent carcinogens, inducing antigenic neoplastic cells. The lack of effect on the number of PFC observed for noncarcinogenic BeP and Ae suggests a possible correlation between carcinogenic power and inhibition of the host's immune response. This agrees with earlier results showing that MCA depresses the number of PFC for a long period, corresponding to the latency period before appearance of MCA-induced sarcomas. It is suggested that the immunodepressive effect of the carcinogens observed may favor the development of antigenic tumor cells, induced either by virus or the carcinogens themselves, or those resulting from spontaneous cellular variation.