T cell lines with dual specificity for strong Mls and H-2 determinants.

To examine the relationship of T cell specificity for Mls vs H-2 determinants, BALB/c (H-2d,Mlsb)(d,b) T cells were stimulated repeatedly in vitro with H-2-compatible, Mls-incompatible DBA/2(d,a) stimulators. This line of T cells gave strong mixed-lymphocyte reactions to the priming Mlsa determinants but, in addition, gave appreciable responses to various foreign H-2 determinants. When this T cell line was subsequently stimulated over a period of 2 mo with Mlsa-negative cells of a particular foreign H-2 haplotype, e.g., H-2k, the cells gave high responses to H-2k determinants but only very low responses to third-party H-2 determinants. Significantly, the cells retained high reactivity for Mlsa determinants. In other experiments, BALB/c T cells positively selected to Mlsa,d-negative H-2-incompatible stimulator cells retained high reactivity for Mlsa determinants. The implications of these findings are discussed.