sIgM expression and signaling capacity in CLL subgroups. sIgM expression (MFI) and sIgM signaling capacity (iCa²⁺ %) were analyzed by flow cytometry in 270 patients with CLL. The patient cohort was divided by IGHV mutational status to assess (A) sIgM expression and (B) anti-IgM signaling capacity. Horizontal lines indicate mean values. The statistical significance of difference was analyzed using the Mann-Whitney test.