Characterization of Immune Response and Mixed Lymphocyte Reactions in Selected Intra-H-2 Recombinant Strains^1,2

The genes controlling the immune response to the random linear terpolymers GAT and GLpro have been mapped in the Ir-1A or Ir-1B subregions with five lines of H-2^a/H-2^a recombinant mice. The I region also contains a third subregion, I-C, which codes for a lymphocyte-activating determinant, Lad₂, controlling mixed lymphocyte reactivity. The mixed lymphocyte responses associated with I-C region disparity are compared with the stimulation noted with other H-2 region differences. Unidirectional lymphocyte activitation was associated with the Lad₂ determinants in selected combinations.