Effect of IL-4 on inhibition of sIgM signaling by ibrutinib and idelalisib. CLL samples were treated with IL-4 for 23 hours or left untreated as a control (NA) and treated then with ibrutinib or idelalisib for 1 hour. Anti-IgM–induced calcium fluxes were analyzed by flow cytometry. (A-B) Representative samples and (C-D) summarized data (n = 18) are shown. Black icons, U-CLL; gray icons, M-CLL. Graphs show medians and the statistical significance of differences between groups. Statistical significance was determined by paired Student t test or Mann-Whitney U test.