H-2 restriction of cytolysis after immunization of minorH congenic pairs of mice

Mice of three congenic resistant lines differing from C57BL/10 at theH-3, H-13, H-7, andH-8 minor histocompatibility loci were used to immunize, and were immunized with, C57BL/10. Cytotoxic cells which were capable of causing rapid lysis of cells from the immunizing strain were generated at least one-way in all combinations tested. In order for a target to be susceptible to cytolysis, it had to carry both the sameH-2 ^b haplotype and the same differential minor histocompatibility alleles as the immunizing strain. That is, B10.C(47N) (H-2 ^b ,H-7 ^b ) anti-C57BL/10 (H-2 ^b ,H-7 ^a ) cytotoxic cells lysed C57BL/10 targets but not B10.BR (H-2 ^k ,H-7 ^a ) targets, nor BALB.B (H-2 ^b ,H-7 ^b ) targets. Crossreactions in the cytotoxic assay suggest that theH-3, H-13 congenic pair —B10.LP and C57BL/10 —may differ in at least two more minor histocompatibility loci which have not yet been defined. Although 6 x 10⁶6 C57BL/10 lymphoid cells primed B10.D2(57N) (H-8 ^b ) mice for a secondary in vitro cytotoxic response, a tenfold higher dose apparently made them tolerant. It is concluded that all minor histocompatibility differences can generate cytotoxic T cells which show specificity both for the minor and major histocompatibility alleles.