Degeneracy of H-2 recognition by cytotoxic T lymphocytes: 10% of the total repertoire is "specific" for a given haplotype and up to 1% is self-H-2 reactive.

The frequency of specific cytotoxic T lymphocytes (CTL) precursors in the total CTL pool was analyzed in a lectin-driven limiting dilution system. We found that up to 10% of the expressed CTL repertoire in a normal mouse is "specific" for a given allogeneic H-2 haplotype. Split-well analysis under clonal conditions demonstrates that the antigens recognized by the effector CTL are H-2 encoded. A high frequency of CTL "specific" for self-H-2 antigens was revealed in all the experiments, accounting for about 1% of the total inducible pool of CTL. These results suggest a high degree of degeneracy of H-2 recognition by CTL and the immunocompetence of self-H-2-reactive CTL precursors in normal individuals.