The recruitment of FcγRIIB was increased in WAS memory. (A-D) TIRFM and IRM analysis of FcγRIIB staining in the contact zone of HCs and WAS patient (P1-12) memory and naive B cells incubated with membrane-tethered Fab′–anti-Ig. The colocalization coefficients between BCR and FcγRIIB staining were determined using NIS-Elements AR 3.2 software (F). Shown are representative images (A-D) and the average MFI (E) or colocalization coefficients (F) (±SD) from ∼300 individual cells of 3 independent experiments. Bars, 2.5 µm. *P < .01, compared with WAS naive or memory B cells.