The aims of this proposal are to determine whether the prototypical chemical carcinogen, benzo(a)pyrene (B(a)P) or its non-carcinogenic structural isomer benzo(e)pyrene (B(e)P) are capable of forming adducts of important lymphocyte cell surface proteins, and whether these altered antigens contribute to B(a)P-induced immunotoxicity and/or carcinogenesis in the mouse. Since electrophilic metabolites of B(a)P are known to react with proteins containing nuceophilic sites adjacent to lipophilic regions, it is hypothesized that Class I (H-2K/D) or Class II (Ia) antigens that may contain such sites are important substrates for B(a)P derivatization. Lymphocytes are capable of polycyclic aromatic hydrocarbon (PAH) metabolism that is inducible in Ah+ mice and may result in intracellular derivitization of membrane proteins with reactive epoxides of BP's. Therefore, lymphocytes will be obtained from the novel mutant, recombinant inbred strains AKXL-38 (Ah-) and AKXL-38(A)(Ah+) and compared throughout this study to determine the dependence of B(a)P/B(e)P effects on inducible benzopyrene metabolism. Surface proteins from lymphocytes exposed to B(a)P/B(e)P in vitro and/or in vivo will be analyzed to measure BP derivatization. To detect, quantitate, and identify B(a)P/B(e)P adducted lymphocyte surface proteins, several monoclonal antibodies to B(a)P and B(e)P will be generated and used in conjunction with antibodies to H-2K/D and Ia in ELISA, analytical gel electrophoresis, and flow cytometry. Subsequently, the effects of B(a)P or B(e)P on lymphocyte function (DNA and protein synthesis, growth and differentiation) will be correlated with the defined B(a)P/B(e)P changes to the lymphocyte surfaces. Further, since it has been demonstrated that chemical alteration of H-2K/D and Ia antigens have been shown to preferentially activate suppressor and helper T-cells, respectively, the ability of benzopyrene-treated cells to alter the functions of untreated immunoregulatory T-cells will be evaluated. It is suggested that benzo(a)pyrene-altered glycoproteins on lymphocyte or other cell membranes, may contribute directly or indirectly to the promotional phase of chemical carcinogenesis, and/or may be the basis for the immunotoxicity of benzo(a)pyrene.
