Circumvention of immunological tolerance to bovine serum albumin by diazotized antigen as a function of hapten density.

Immunological tolerance was induced in adult guinea pigs by the injection of 10-100 mg of centrifuged BSA. The tolerant state was readily circumvented, in terms of both humoral antibody response and delayed hypersensitivity, by the immunization with sulfanilated BSA with different degree of conjugation. The level of anti-BSA and intensity of the skin reactions to BSA evolked in animals with circumvented tolerance responding to the challenge immunization with sulfanilated BSA were inversely related to the number of sulfanil groups per BSA molecule. On the basis of the experimental data, the mechanism of the circumvention of tolerance is discussed.