Examples of PCR amplification of de novo CD5⁺ DLBLs with genomic DNA of cases no. 1, 2, and 11 (A) and with cDNA of cases no. 1, 2, 6, and 11 (B). PCR products were electrophoresed on a 4% agarose gel, stained with ethidium bromide, and visualized under UV light. Lane M, molecular weight standard ◊X174/Hae III. Lane N, negative control. (A) Cases no. 1, 2, and 11 all presented monoclonal patterns whose VH genes were amplified. (B) VH1 through VH6 were amplified with corresponding VH1 to VH6 gene family-specific leader primer and a JH primer, respectively. In cases no. 1, 2, and 11, monoclonal patterns were obtained only in one of VH families, whereas in case no. 6, they were obtained in two VH families (VH3 and VH5). However, PCR products of VH3 in case no. 6 were polyclonal, as confirmed by sequencing.