Figure 8. IL-5-mediated induction of killer B cell function, but not FasL expression, is inhibited by IL-4.

CD19⁺ B cells from naïve mice were cultured for five days with CD40L Fb and IL-4, IL-5, or both cytokines concurrently. (A) The ability of B cells stimulated under these conditions to induce apoptosis in activated CD4⁺ T cells was then assessed as in Figure 6. Apoptotic cells were identified and enumerated (mean ± SEM) on the basis of positive staining for Annexin V by flow cytometry. (B) B cells were cultured with CD40L-expressing fibroblasts in the presence or absence of IL-4 and IL-5, or in the presence of both cytokines. Cells were harvested after 5 days in culture and cell lysates were probed for FasL and β-Actin proteins as in Figure 5G. ***p<0.001 and ****p<0.0001.