Characterization of the Ia antigens involved in suppressor T cell generation in the rat.

The WRC rat, an intra-class II recombinant strain (RT1.B beta nB alpha aD alpha, beta a), was used to study the relative roles of the two class II loci in mixed lymphocyte reaction (MLR) proliferation and suppressor T cell (Ts) generation. Both MLR proliferation and Ts generation were noted in cultures of WRC with DA (RT1a) stimulator cells. In contrast, cultures of WRC with BN (RT1n) stimulator cells proliferate but do not generate significant amounts of Ts. The data suggest that RT1.B beta incompatibility is important in the generation of Ts in the WRC rat. Suppressor cells generated in cultures of WF (RT1u) with WRC stimulator cells potently suppressed a WF + WRCx test MLR, with less suppression when tested against either the WF + DAx or WF + BNx MLRs. The latter experiments suggest that Ts clones may be produced to either class II subregion, and therefore that MLR proliferation and Ts induction are not necessarily linked, but vary with particular genotypes. The current lack of other rat intra-class II recombinant strains precludes assignment of suppressor induction/activation to a single locus.