Preferential rearrangement of Vκ4 gene segments in Pre-B cell lines

Abstract

Examination of the in vitro Vκ gene rearrangements of murine adult bone marrow-derived pre-B cell lines reveals that 21 of 25 (84%) cell lines have rearranged a member of the Vκ4 family. In contrast, analysis of two Vκ cDNA libraries prepared from LPS-stimulated adult spleen cells indicates that only 17% of the Igκ cDNAs contain sequences belonging to the Vκ4 gene family. Half of the pre-B cell lines examined also share an 8-kbp BamHI reciprocal product (rp). However, these rp do not involve the same Vκ gene, indicating that conserved BamHI sites exist 3′ of some Vκ genes. This rp is also readily detected in DNA from normal adult spleen cells, suggesting that the in vitro rearrangements examined in this study are representative of κ rearrangements that occur in vivo. We suggest that, unlike the diverse Vκ repertoire expressed by mature B cells, the germline Vκ segments involved in initial rearrangements of the IgκK locus are highly restricted, and that an initial Vκ4 rearrangement is probably followed by other, more random recombination events.