Generation of T cell repertoire. Two distinct mechanisms for generation of T suppressor cells, T helper cells, and T augmenting cells.

The present studies were carried out to characterize the influence of the T cell maturation environment on a repertoire of Th cells, T augmenting cells, and Ts cells, which were shown to construct a minimal regulatory circuit to regulate a helper function of class II-restricted Th cells. A repertoire of keyhole limpet hemocyanin-specific Th cells was influenced predominantly by I-A molecules of the T cell maturation environment, whereas a repertoire of T augmenting cells was determined by both I-A and I-E molecules. These repertoires were not influenced by the priming with Ag. A repertoire of Ts cell factor-producing Ts cells was not influenced by the T cell maturation environment, but rather was determined by the I-J haplotype of the APC utilized for priming with Ag. In contrast, a repertoire of novel cognate type Ts cells, which inhibit class II-restricted Th cell function in a restriction-restricted manner, was influenced by both I-A and I-E molecules of the T cell maturation environment. These results demonstrate the two distinct mechanisms for generating a T cell repertoire: a selection by class II molecules of the T cell maturation environment before the priming with foreign Ag and a selection by priming with APC and Ag.