Regulation of anti-IgM– and anti-IgD–induced calcium flux by IL-4. CLL samples were treated with IL-4 for 24 hours or left untreated as a control (NA). (A) CLL cells were subsequently treated with the JAK1/3 inhibitor (CP) for 1 hour and then stimulated with soluble anti-IgM and calcium flux assessed by flow cytometry. A representative flow cytometry plot is shown. (B) anti-IgM (n = 38) and (C) anti-IgD (n = 19) signaling responses were quantified using calcium flux analysis. Graphs show fold change in signaling (%responsive cells with IL-4/%responsive cells in the absence of IL-4). Statistical significance of differences are shown. (D) Effect of IL-4 titration on anti-IgM–induced calcium fluxes as previously described. Statistical significance was determined by paired Student t test or Wilcoxon matched pairs signed rank test.