Altered expression of the Salmonella typhimurium-specific B-cell repertoire in mice chronically treated with antibodies to immunoglobulin D

Abstract

Using a modification of the splenic focus assay, we analyzed the Salmonella typhimurium-specific B-cell repertoire in salmonella-susceptible BALB/c mice. Although these mice normally succumbed to salmonella infection before antibody was produced, they appeared to have splenic S. typhimurium-specific B-cell precursors that could be activated to differentiate and secrete antibody in a manner which was quantitatively and qualitatively identical to that of salmonella-resistant mouse strains. We also analyzed the primary S. typhimurium-specific B-cell repertoire in BALB/c mice that had been chronically treated with antibodies to immunoglobulin D (IgD) and therefore had no surface IgD-positive B cells. Although the frequency of S. typhimurium-specific precursors in these mice was similar to that of control mice, there was an apparent alteration in the isotype distribution pattern in anti-IgD-treated mice. Control mice generated a significantly greater proportion of IgG-secreting clones than did anti-IgD-treated mice. In addition, a greater proportion of S. typhimurium-specific clones from control mice secreted IgG2 than secreted IgGl, and those clones that secreted IgG2 but not IgM, IgG3, or IgGl were >20-fold more common in control than in anti-IgD-treated mice. Finally, we analyzed the immune response of control and anti-IgD-treated mice to a live avirulent vaccine, S. typhimurium SL3235. Although both groups were protected after challenge with a live virulent S.