CD40LG and B-cell chronic lymphocytic leukemia: Regarding plasma Ig titers, soluble IgM levels were significantly reduced in both MBLhi (P = 0.03) and CLL-0 (P = 0.008) (Fig. 2e); in addition, MBLhi showed reduced IgG2 and IgG4 soluble levels (Supplementary Figure 5C-E) while CLL-0 patients displayed overall decreased plasma levels of all IgG-subclasses (P ≤ 0.02), particularly also of those encoded downstream in the IGHC gene (i.e., IgG2, IgG4, and IgA2; P ≤ 0.001; Fig. 2f).