Evaluation of the CSR process together with BSAP, Pax-5/Δ-Ex8, and AID translation in CLL B cells. Western blot analysis of BSAP, Pax-5/Δ-Ex8 spliced variant (A), and AID protein (B) were detected with specific antibodies from 3 representative patients (nos. 39, 28, and 01). Relative molecular weight is indicated in kilodaltons (kDa). (C) Flow cytometry analysis shows IgM and IgG isotypes in B-CLL lymphocytes from patients 01 and 39, respectively. Histograms show the percentage of cells expressing IgM, IgG, or both IgM/IgG.