IDENTIFICATION OF A RECOMBINATIONAL BREAKPOINT AT THE BAT5 LOCUS IN 3INTRA-H-2 RECOMBINANT INBRED MOUSE STRAINS

We have analyzed the S/D region in 14 inbred mouse strains by restrict ion fragment length polymorphism (RFLP) using human BAT2 and BATS gene s as probes. In all recombinant strains, the recombinational breakpoin t mapped centromeric to Bat-2 (D17H6S51E). In recombinant strains B6.R 4, B6.AK1 and B10.BYR1, recombination occurred within or close to the Bat-5 (D17H6S82E) locus. The immunogenicity of B10.BYR1 and B6.R4 bone marrow cell (BMC) grafts differs from that of both sets of parents, a s if genes at or just centromeric to Bat-5 are involved. The phenotype of B6.AK1 BMCs (K-b D-k) is similar to that of the H2(k) parent sugge sting no changes occurred. However, RNA blot analysis has shown that t he Bat-5 gene is expressed well in bone marrow cells of B10,BR mice bu t not in B6.AK1 marrow eels. Analysis of a limited number of tumor cel ls of hemopoietic origin identified a single transcript for Bat-5. Our present data identify a recombinational hot spot at the Bat-5 locus, The expression of Bat-5 or a nearby gene may influence the immunogenic ity of BMCs.