Analyses of CD18 expression on B cells and T cells of mutation carriers and noncarriers. Peripheral blood mononuclear cells were stained as previously described¹³  with the following antibodies: anti–CD19-allophycocyanin, anti–CD5–phycoerythrin cyanine dye (to identify the CLL cell population), anti–CD3-fluorescein isothiocyanate (to identify the T-cell population) and one of the following phycoerythrin-conjugated antibodies: anti–immunoglobulin G1-isotype control or anti-CD18 (BD Biosciences, Franklin Lakes, NJ). Each sample was run in duplicate. Cells were analyzed on a fluorescence-activated cell sorter (FACS) Canto II flow cytometer (BD Biosciences) using FACS-DIVA 6.1.1 and FlowJo software (Version 8.8.6; TreeStar, Ashland, OR). (A) Expression of CD18 in B cells of representative normal individual (black line), CLL patient without CD18 mutation (blue line), and CLL patient with CD18 mutation (red line). (B) Expression of CD18 in B cells of 9 CLL patients (with CD18 mutation), 25 CLL patients without CD18 mutation, and 10 unaffected individuals. (C) Expression of CD18 in T cells of 9 CLL patients (with CD18 mutation), 25 CLL patients without CD18 mutation, and 10 unaffected individuals.