To begin to directly assess whether CLL B cells promote T cell differentiation to IL-17F-producing Th17s, purified CD4+ T cells from three independent CLL patients were cultured alone or together with autologous CLL B cells for 7 days in the presence (or absence) of various combinations of Th17-polarizing cytokines (IL-6, IL-1β, IL-1β + IL-6, IL-6 + IL-1β + IL-23). This evidence concerns the gene CD4 and B-cell chronic lymphocytic leukemia.