Microbial adjuvant and autoimmunity. I. Induction of antibody responses to syngeneic tissue extracts in mice treated with capsular polysaccharide of Klebsiella pneumoniae.

With the use of the capsular polysaccharide of Klebsiella pneumoniae (CPS-K) as a powerful adjuvant, high precipitin responses could be induced in mice to syngeneic eyeball extracts and thyroid gland extracts which were normally nonimmunogenic. Only very weak responses were induced to eyeball extracts by Freund's complete adjuvant. Repeated administrations of the antigens mixed with CPS-K at time intervals of 30 days (more than twice for the eyeballs or more than three times for the thyroid glands) were required for induction of high precipitin responses. Antibody responses detectable by the immunofluorescent technique could be induced to syngeneic lymphoid tissue extracts by injecting the mixture of antigen and CPS-K more than five times at time intervals of 30 days. These findings suggest that repeated stimulation by autoantigens together with such a strong adjuvant as CPS-K can terminate natural tolerance against autoantigens.