Similar characteristics of the CDR3 of VH1‐69/DP‐10 rearrangements in normal human peripheral blood and chronic lymphocytic leukaemia B cells

The variable heavy chain (V H ) gene segment V H 1‐69/DP‐10 has been shown to be over‐represented in B‐cell chronic lymphocytic leukaemia (CLL). Because of certain similar characteristics of their complementarity determining region 3 (CDR3), including preferential utilization of J H 6 elements and an extended length, it has been suggested that antigenic stimulation might be involved in leukaemogenesis. Utilizing single‐cell PCR to amplify and sequence genomic DNA from individual normal human peripheral blood B cells, we have obtained 7/421 productively and 1/69 nonproductively rearranged V H genes that used V H 1‐69/DP‐10. All productive rearrangements were unmutated, used J H 6 and had an average CDR3 length similar to that previously found in V H 1‐69/DP‐10‐expressing CLL cells. These results suggest that CLL may arise from B cells commonly found in the peripheral B‐cell repertoire and do not represent expansion of a unique subset of specific antigen‐reactive B cells.