FIGURE 7.

Role of CD40L-CD40 interactions in induction of GC B cells and class switching. nvB cells from unimmunized WT or CD40^–/– mice were co-cultured with primed Tfh cells in the presence or absence of primed Tfr cells. Cultures were stimulated with anti-CD3 (A,C) or anti-CD3/IgM (B,D). Anti-CD40L was added to cultures in panels C and D. Differentiated B cells were gated as Fas⁺GL7⁺ B220⁺ IgD^lo CD4^– and switched B cells were gated as IgG1⁺GL7 + IgD^loB220⁺CD4^–. (D) Statistical results are from five independent experiments showing SEM (n = 5). *p < 0.05, **p < 0.005, unpaired Student t-test.