Ig gene rearrangements on individual alleles of Abelson murine leukemia cell lines from (C57BL/6 x BALB/c) F1 fetal livers.

We have previously shown that selection of Ig H chain V region genes used by colonies obtained from splenic B cells and fetal liver pre-B cells was dependent on strain-specific factors. Moreover, by examining the V gene usage in strains congenic at the Igh locus, we also determined that the strain-specific factor was encoded by sequences lying outside of the Igh locus. We decided to examine whether there are differences in Vh gene rearrangement between alleles in an F1 strain. To do this analysis we chose to examine the relative Ig H chain V region gene usage of pre-B cell lines derived from (C57BL/6 x BALB/c)F1 fetal liver cells by Southern blot analysis. We found a high frequency of Vh-gene rearrangements (77% of the alleles had VDJ rearrangements) and these rearrangements occurred to Vh-genes throughout the Vh locus and were not confined to the D-proximal Vh-genes as has been previously observed with lines from other mouse strains. The Vh-gene usage pattern is similar on both alleles indicating that at least one of the determinants of which Vh-gene is used is trans-acting and acts similarly on each allele. Furthermore, one allele, Ighb (donated by the C57BL/6 parent), rearranged Vh-genes more frequently than the other allele, Igha (donated by the BALB/c parent) suggesting that one of the determinants of Vh-gene rearrangement may be acting in an allele-specific manner.