Delayed hypersensitivity to hapten-skin protein conjugates in guinea pigs sensitized to benzo(a)pyrene.

Guinea pigs were sensitized to 3,4-benzo(a)pyrene, by epicutaneous application or by footbad injection in Freund's complete adjuvant. Conjugates of benzo(a)pyrene and guinea pig skin protein formed by ultraviolet radiation could elicit cutaneous delayed hypersensitivity and could inhibit the migration of macrophages obtained from guinea pigs sensitized to the carcinogen. Extracts of benzo(a)pyrene-treated guinea pig skin and conjugates formed in vitro with benzo(a)pyrene isocyanate were unable to consistently elicit delayed hypersensitivity reactions in vivo or in vitro. The results indicate a high degree of hapten-carrier specificity to contact sensitivity to benzo(a)pyrene.