Evidence for a third, Ir -associated histocompatibility region in the H-2 complex of the mouse

Skin grafts transplanted from B10.HTT donors onto (A.TL × B10)F 1 recipients are rapidly rejected despite the fact that the B10.HTT and A.TL strains should be carrying the same H-2 chromosomes and that both the donor and the recipient contain the B10 genome. The rejection is accompanied by a production of cytotoxic antibodies against antigens controlled by the Ir region of the H-2 complex. These unexpected findings are interpreted as evidence for a third histocompatibility locus in the H-2 complex, H-2I , located in the Ir region close to H-2K . The B10.HTT and A.TL strains are postulated to differ at this hypothetical locus, and the difference between the two strains is explained as resulting from a crossing over between the H-2 t1 and H-2 s chromosomes in the early history of the B10.HTT strain. The H-2 genotypes of the B10.HTT and A.TL strains are assumed to be H-2K s Ir s / k Ss k H-2D d and H-2K s Ir k Ss k H-2D d , respectively. Thus, the H-2 chromosomes of the two strains differ only in a portion of the Ir region, including the H-2I locus. The B10.HTT( H-2 tt ) and B10.S(7R)( H-2 th ) strains differ in a relatively minor histocompatibility locus, possibly residing in the Tla region outside of the H-2 complex.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/46727/1/251_2005_Article_BF01564045.pd