Since the previous set of experiments was performed with whole PBMC cultures, the higher percentages of IL-17F-expressing CD4+ T cells observed in CLL PBMCs could reflect an inherent difference in the CLL T cells themselves or a modulatory effect mediated by autologous CLL B cells or another immune cell present in the CLL PBMC population. This evidence concerns the gene CD4 and B-cell chronic lymphocytic leukemia.