High frequency and nonrandom distribution of alloreactivity in T cell clones selected for recognition of foreign antigen in association with self class II molecules.

Previous studies have demonstrated that a single T cell clone can respond to both a foreign antigen in the context of self major histocompatibility complex (MHC)-encoded molecules (self plus X) and to an allogeneic class I or class II molecule in the absence of antigen (non-self). We have used limiting dilution of T cells obtained from the draining lymph nodes of antigen-primed B10.A mice to establish a large number of T cell clones that recognize either GAT, pigeon cytochrome c, or sheep insulin in association with syngeneic antigen-presenting cells. Sixty-two antigen-specific T cell clones were assayed for their ability to proliferate in response to a panel of nine different allogeneic haplotypes. Of these, 38 (61%) responded to at least one allogeneic haplotype, and 15 of the 38 (39%) responded to more than one allogeneic stimulator. In addition, the patterns of alloreactivity varied with the immunizing antigen. The GAT-specific T cells had at least one responder to every haplotype tested, although H-2u-responsive T cell clones were the most common. In contrast, no pigeon cytochrome c-specific T cells responded to stimulators of the H-2u haplotype, but rather predominantly responded to H-2t4/H-2s and H-2i5/H-2b. Finally, sheep insulin-reactive T cell clones preferentially responded to H-2u stimulators, although stimulation by antigen-presenting cells of the H-2p and H-2q haplotypes was also common. A chi 2 analysis of the data demonstrated that the dependence of the pattern of alloreactivity observed upon the antigen used for immunization was statistically significant (p less than 0.01). The high frequency of alloreactivity found in antigen-specific T cell clones is discussed, as well as the implications that the antigen-dependent skewing of the distribution of alloreactivity have for a one-receptor model vs a two-receptor model of T cell recognition.