T cell proliferation induced by anti-self-I-A-specific T cell hybridomas. Evidence of a T cell network.

Allo-I-A-reactive T cell hybridomas were generated from MLR-activated lymphoblasts. Cloned hybridomas T1.203, T1.321, and T1.426 were stimulated by I-Ab determinants, as shown by their ability to secrete IL-2 in response to a panel of MHC-recombinant mice. T2.146, T2.205, and T3.116 were found to be specific for I-Ak determinants using a similar panel of MHC-recombinant mice. Inhibition of IL-2 secretion by anti-I-A mAb confirmed these data. Some I-Ab-specific hybrids stimulated the proliferation of T cells from C57BL/6 (H-2b) mice. Similarly, some I-Ak-specific hybrids stimulated the proliferation of T cells from C3H/HeJ (H-2k) mice. These hybrids expressed no detectable surface I-A, and stimulation of T cells was not inhibited by anti-I-A mAb. These results are consistent with the hypothesis that normal mice possess a population of T cells responsive to idiotypic determinants on anti-MHC class II T cell receptors.