Phenotype of aCL IgM-bearing B cells. Representation of the 3 color FACS analysis on viable (PI^-) lymphocytes after staining with labeled CL vesicles, anti-IgM and anti-CD27 of PBMCs from patient 1 (A) and patient 3 (B). IgM⁺/CL⁺ double-stained population is shown for patient 1 (Ai) and patient 3 (Biii). Panels Aii and Biv are gated on the double-stained population IgM⁺/CL⁺. The percentage of CD27⁺ cells is given.