Thymic epithelium induces neither clonal deletion nor anergy to Mls 1a antigens

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Abstract
Grafting of thymic anlagen from day‐10 DBA/2 (H‐2d; Mls‐1a) embryos to newborn athymic BALB/c (H‐2d; Mls‐1b) mice leads to reconstitution of T cell populations in the recipients. Analysis of adult chimeras shows that their Vβ T cell receptor (TcR) repertoires, particularly Vβ6 and Vβ8.1, do not significantly differ in most animals (10 out of 13) from those scored in control chimeras that received syngeneic thymic anlagen. In all cases analyzed, such Mls‐1a−reactive T cells could be stimulated at levels comparable to control responses, both in vitro and in vivo. The few cases in which Mls‐1a reactive Vβ TcR were reduced seem to reflect the variability in TcR Vβ repertoires found inthis experimental system. In contrast, BALB/c mice, injected at birth with DBA/2spleencells show a marked, albeit variable, reduction in the frequencies of Vβ6− and Vβ8.1‐bearing CD4+ T cells, and lower frequencies of Mls‐1a−reactive T cells in limiting dilution analyses. It appears, however, that Vβ6− and Vβ8.1‐bearing T cells remaining in these mice are functionally competent. We conclude that Mls‐1antigens are not expressed by thymic epithelium.