Analyses of Ig VHDJH rearrangements expressed by B-CLL cells have provided insights into the antigen receptor repertoire of B-CLL cells and the maturation stages of B-lymphocytes that give rise to this disease. However, less information is available about the L chain V gene segments utilized by B-CLL cells and to what extent their characteristics resemble those of the H chain. We analyzed the VL and JL gene segments of 206 B-CLL patients, paying particular attention to frequency of use and association, mutation status, and LCDR3 characteristics. Approximately 40% of B-CLL cases express VL genes that differ significantly from their germline counterparts. Certain genes were virtually always mutated and others virtually never. In addition, preferential pairing of specific V L and JL segments was found. These findings are reminiscent of the expressed VH repertoire in B-CLL. However unlike the V H repertoire, VL gene use was not significantly different than that of normal B-lymphocytes. In addition, Vκ genes that lie more upstream on the germline locus were less frequently mutated than those at the 3′ end of the locus; this was not the case for Vλ genes and is not for VH genes. These similarities and differences between the IgH and IgL V gene repertoires expressed in B-CLL suggest some novel features while also reinforcing concepts derived from studies of the IgH repertoire.
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