Genetic Studies in Inbred Rats.

SUMMARY The relationship between the mixed leukocyte reaction (MLR) and the serologically defined antigens of the major histocompatibility complex was examined in twenty‐three strains of genetically inbred rats. Interstrain cell combinations involving representative members of the different major Ag‐B groups were associated with significant MLR responses. Strain combinations within a single Ag‐B group were never associated with significant MLR responses, suggesting that non‐Ag‐B loci probably do not play an important role in MLR reactivity among inbred strains of rats. The WKA and KGH strains, representing newly defined histocompatibility groups, were also examined. The WKA strain (Ag‐B8) showed positive MLR responses against representative members of all the different Ag‐B groups, including the KGH strain. The KGH strain (Ag‐B7) had positive MLR responses against all Ag‐B groups except Ag‐B1: no reactions occurred with three strains in this group, and inconsistent and weak reactivity was observed with a fourth strain (F344).