Regulation of the Antibody Response to Type III Pneumococcal Polysaccharide

Abstract

Abstract A modification of the technique of localized hemolysis-in-gel was used, in conjunction with class-specific anti-γ-globulin sera, for detecting IgG and IgA plaque-forming cells (PFC) in mice immunized with Type III pneumococcal polysaccharide (SSS-III). Small, but significant, numbers of IgG and IgA PFC could be detected, and the numbers increased at least 10-fold after treatment with antilymphocyte serum (ALS). The results of plaque-inhibition studies affirmed that such PFC represent cells making antibody having the same class-specificity as the antiserum used for their detection. These findings suggest that the magnitude of not only the IgM, but also the IgG and IgA, antibody response to SSS-III is governed by the activities of regulatory thymus-derived cells having opposing functions and that ALS-induced enhancement cannot be attributed to a reversal or alteration of antibody-mediated feedback inhibition. Furthermore, the kinetics observed for the development of the IgM, IgG, and IgA antibody response to SSS-III suggest that clones of precursor cells, restricted mainly to the synthesis of one class of immunoglobulin, exist before immunization and increase independently in size upon antigenic stimulation.