Regulation of the Antibody Response to Type III Pneumococcal Polysaccharide

Abstract

Abstract The present study was conducted primarily to obtain information concerning the mechanism by which suppressor thymic-derived (T) cells influence the magnitude of the antibody response to type III pneumococcal polysaccharide (SSS-III). This was accomplished by examining the effects of treatment with antilymphocyte serum (ALS) and Velban, a mitotic inhibitor, on the kinetics for the appearance of plaque-forming cells (PFC) in mice immunized with SSS-III. Without ALS-treatment, the kinetics were essentially biphasic. First, there was a phase during which PFC appeared at a relatively rapid rate; this was followed by a phase during which the rate of appearance of PFC gradually declined until maximal numbers were attained. In contrast, similar rate changes were not noted for mice given ALS; here, PFC increased at a uniform exponential rate throughout the 1st 5 days of the antibody response. Velban completely arrested the development of additional PFC in ALS-treated but not non-ALS-treated mice. These findings indicate that suppressor T cells act primarily by limiting the extent to which antibody-forming bone marrow-derived cells proliferate following immunization.