Elevated CD20⁺ cell numbers in the peripheral blood of WM patients during the stable phase of disease are polyclonal B cells. CDR3 of unfractionated peripheral blood B cells was analyzed by RT-PCR using FR3 and fluorescence-labeled J_Hc primer (Table 2) and DNA fragment analysis using capillary electrophoresis. The PCR product includes 26 bp upstream and 36 bp downstream of CDR3. Corrected length of CDR3 is as indicated.