CD40-activated CLL B-cells exhibit an activated B-cell phenotype and morphology (192, 196, 264, 265), with upregulated IRF4 expression, decreased expression of CD20 and CD184, and enhanced expression of CD18, CD40, CD54, CD80, CD86, and HLA-DR, and secrete moderate levels of IgM (196, 265, 266). This evidence concerns the gene IRF4 and B-cell chronic lymphocytic leukemia.