A rare D-region recombination event which gave rise to the B10.RQDB major histocompatibility complex haplotype has been examined to ascertain the nature of the crossover and to determine which class I genes are present in the new alignment of D-region genes. Serologic analyses have shown that the B10.RQDB major histocompatibility complex recombinant mouse inherited the H-2D(d) gene from the B10.T(6R) parental line and the H-2Db gene from the B10.A(2R) parental line, representing the first example of an intra-D-region crossover resulting from an intercross. Previous molecular genetic analyses of the d and b haplotypes revealed structural diversity in the organization of their D-region gene clusters. Hence, the D region is comprised of five class I genes in the d haplotype and only one in the b haplotype. Because allelic relationships among the various D-region genes are not defined, either a homologous or nonhomologous alignment of genes has generated the RQDB crossover. Therefore, the possibility that all three D-region antigen-presenting molecules (D(d), L(d), and Db) might be encoded by the RQDB haplotype was examined. Fluorescence-activated cell sorter and cytotoxic T lymphocyte analyses revealed no detectable levels of H-2L(d) cell-surface expression, confirming earlier studies with antibody-mediated cytotoxicity and immunoprecipitation. Southern blot analysis localized the recombination point to within a 1-kb region at the centromeric end of the H-2L(d) gene on the B10.T(6R) chromosome in a region of high homology to the H-2Db gene on the B10.A(2R) chromosome. Together, these studies define the D region of the RQDB haplotype as containing the five class I genes: D(d), D2(d), D3(d), D4(d), and Db. In addition to providing insight into rare recombination events in the D region, the B10.RQDB mouse should be a useful tool for exploring the function of D-region genes.
|Original language||English (US)|
|Number of pages||7|
|Journal||Journal of Immunology|
|State||Published - 1987|
ASJC Scopus subject areas
- Immunology and Allergy