The Induction of Immunologic Tolerance in Guinea Pigs Infused with Dimethylbenz(a)anthracene

The infusion of 7,12 dimethylbenz(a)anthracene (DMBA) dissolved in DMSO:glycofurol into adult guinea pigs rendered most recipients unresponsive to the induction of contact sensitization with DMBA, either by injection in adjuvant or topical application. The results were similar when guinea pigs infused with DMBA dissolved in Upjohn fat emulsion, were challenged with DMBA in adjuvant, but studies attempting topical sensitization to demonstrate unresponsiveness were inconclusive. Mam-mary tumors appeared after a latent period of 8 to 11 mo in 4 guinea pigs infused with DMBA in fat emulsion in which topical sensitization with DMBA was attempted.