Genetic analyses of alloreactions between recently wild and classical inbred strains of Syrian hamsters: evidence in favor of a major histocompatibility complex.

Cytotoxic alloantisera were raised between recently wild and classical inbred strains of Syrian hamsters. Antisera produced by immunizing the classical inbred strains with tissue from the partially inbred, recently wild hamsters detect several specificities shared between the classical and recently wild strains. Reciprocal mixed lymphocyte reactions between the two different groups of hamsters suggest that the new source of hamsters possesses several unique MLR phenotypes which may represent new Hm-1 haplotypes. Moreover, several recently wild strains express MLR phenotypes quite similar if not identical to the Hm-1a haplotype of the inbred strain, MHA. Genetic analyses of alloreactions between domestic inbred and recently wild strains suggest that a single locus or chromosomal region encodes the allodeterminants that induce strong MLR reactivity. Six unique MLR phenotypes have been defined which most likely represent haplotypes of the hamster MHC equivalent, Hm-1. Genetic linkage studies indicate that some alloantisera detect determinants encoded by loci closely linked to the MLR locus, and therefore define Hm-1 determinants. Moreover, other alloantisera recognize determinants encoded by a locus that is unlinked to Hm-1. These studies suggest that Syrian hamsters express a polymorphic MHC equivalent, Hm-1, which encodes determinants that induce both cell-mediated and humoral alloreactivity.