CD4+ T cells regulate the magnitude of the antibody response to several helper T cell independent antigens.

The effect of prior depletion of CD4+ T cells on the magnitude of the primary antibody response to several antigens considered to be helper T cell independent (TI) was examined. Treatment of mice with the monoclonal antibody GK1.5 to remove CD4+ T cells had little effect on the magnitude of the specific antibody response to the lipopolysaccharide (LPS) of Escherichia coli 0113; however, such treatment reduced the magnitude of the splenic IgM antibody response to E. coli 055 LPS, Serratia marcescens LPS, TNP-Ficoll, and Type III pneumococcal polysaccharide (SSS-III), compared to control untreated or rat IgG treated mice. Thus, CD4+ T cells positively influence of magnitude of the antibody response to the majority of helper T cell independent antigens tested.