The Basis for Conflicting Results Obtained in Studies on the Plaque-Forming Cell Response to Type III Pneumococcal Polysaccharide

Open Access
Publisher Website
Google Scholar
Abstract
Treatment with several preparations of anti-lymphocyte or anti-thymocyte serum (ALS or ATS)1 has been shown to cause a significant increase (10- to 20-fold) in the magnitude of the plaque-forming cell (PFC) and serum antibody response to Type III pneumococcal polysaccharide (SSS-III) in different strains of mice (1–4); such enhancement is evident with respect to both PFC/106 nucleated spleen cells and PFC/spleen, indicating that it is not due simply to splenomegaly (3). These observations have been confirmed using preparations of ALS and SSS-III, made independently by different methods (5). In all of these studies, sheep erythrocytes, sensitized with purified SSS-III by the CrCl3 coupling method (6), were used as indicator cells for the detection of PFC making antibody specific for SSS-III. Despite these reproducible findings and their independent confirmation, some investigators have reported that treatment with ALS produces either no change, or a significant reduction in the number of PFC found after immunization with this antigen (7–9); here, sheep erythrocytes, sensitized with uncharacterized filtrates from broth cultures of pneumococci (10), were used as indicator cells in assays for PFC.