Studies on Pneumococcal Polysaccharide

[摘要] Various mechanisms which have been suggested to account for “immunological paralysis” following injection of large doses of SI have been reviewed. Experimental evidence does not support some of these.When 500 μg of C14-SI is injected into mice the radioactivity of splenic extracts remains essentially unaltered for the period of one year, indicating persistence in the animal tissue of the antigen or of some complex formed with it. In contrast free antigenic C14-SI in the spleen at the end of one year is reduced to approximately 1.5 per cent of that present two days after injection. Preliminary experiments indicate that mice which have been immunized by injection of an antigenic dose of SI promptly lose their immunity when given 500 μg, as would be expected if the mechanism postulated is true.These results are consistent with the hypothesis that “immunological paralysis” is a result of the removal of antibodies as rapidly as formed through union with the excess antigen. This mechanism would account for the fact that larger than minimal dosages of SI require longer periods for the production of free antibodies. Studies of dosage size might show that many antigens may produce short term deleterious effects on the degree of immunity produced when injected in large doses.

[学科分类] 生物科学（综合）