CD8(+) T lymphocytes in double alpha beta TCR transgenic mice. I. TCR expression and thymus selection in the absence or in the presence of self-antigen

We derived Rag2-deficient mice bearing two rearranged ap TCR transgenes, on e specific for the HY male Ag and the second specific for the gp33-41 pepti de of lymphocytic choriomeningitis virus, both restricted to the MHC H-2D(b ) class I molecule. We found that, in female double transgenic (DTg) mice, most CD8 T cells express only the TCR beta chain from the aHY transgene. By comparing the mRNA species for both beta -chains, we observed that in T ce lls from DTg mice the aHY TCR beta chain transcripts are abundant, whereas the anti-lymphocytic choriomeningitis virus TCR beta chain transcripts are rare. In contrast to TCR beta chain expression, most of the T cells from DT g mice express two TCR alpha chains. We examined the thymus selection of th e dual-receptor CD8 T cells in the presence of self-Ag. We found that the p resence of a second TCRa chain allows a significant number of CD8 T cells e xpressing a self-reactive receptor to escape central deletion and migrate t o the peripheral pools of male mice. Differences in TCR and coreceptor expr ession between female and male MoaHY and DTg mice suggest that peripheral T cell survival requires an optimal level of signaling, which implies a proc ess of "adaptation" of lymphocyte populations to the host environment.