HLA-E and B-cell chronic lymphocytic leukemia: The combination of IL-4 and CD40L together led to a further increase in HLA-E expression on CLL cells (mean IL-4 + CD40L 160% (P < 0.05), IL-4 121% and CD40L 132%), and increased total HLA to a lesser extent (118%, P < 0.001) (Fig. 7A, B).