Surface FcμR expression by B and T cells in CLL patients and healthy donors. (A) A representative profile of each group. PBMCs from CLL patients with a mutated (MT-CLL; n = 21) or unmutated (UM-CLL; n = 19) genotype and from 23 healthy donors were stained with biotin–anti-FcμR (plus PE-SA), FITC–anti-CD5, and APC–anti-CD19 mAbs or with the corresponding, isotype-matched control mAbs. The CD5⁻/CD19⁺ non-CLL B, CD5⁺/CD19⁺ CLL B, and CD5⁺/CD19⁻ T cells in patients and the CD5⁻/CD19⁺ B and CD5⁺/CD19⁻ T cells in healthy donors were gated (boxes in left panels) and examined for their FcμR expression (open profiles) and background staining with control mAbs (shaded profiles). Purple lines drawn through the UM-CLL peak are included to allow comparison of the staining intensities in the different groups. (B) Cell surface FcμR levels on the indicated cell populations from MT-CLL (green), UM-CLL (red), and healthy (yellow) blood samples are shown as the mean fluorescence intensity ratio (MFIR; ± SD), calculated as the ratio of FcμR MFI/control MFI. Comparisons by paired and pooled t tests are indicated in black and blue lines, respectively. Other P values are listed in Table 1. (C) A representative profiles of comparative analysis of anti-FcμR (first and third rows) and anti-TOSO (second and fourth rows) mAbs in MT-CLL (top 2 panels) and UM-CLL (bottom 2 panels).