H-2 antigen variants in a cultured heterozygous mouse leukemia cell line

An H-2 antigen variant, referred to as ?4 + 31 clone 1, was selected by its resistance to an anti-H-2D^d antiserum (BALB.G anti-BALB/c.H-2 ^g antiH-2 ^d ). When tested by cell-mediated cytolysis, this variant was found to be sensitive to cytolytic T lymphocytes raised in the same donor-host combination as that used in raising the antiserum. Further CML characterization of this variant, reported here, indicates that the cell line is in fact resistant to anti-H-2D^d killer cells raised in a more restricted immunization, viz. BALB.G anti-BALB/cH-2 ^db ,H-2 ^g anti-H-2 ^db . It is, however, sensitive to cytolytic cells raised in (BALB.B xBALB/c-H-2db) F¹ H-2 ^b /H-2 ^db ) against the BALB/c strain. These results suggest that the variant does not express H-2D^d itself, but probably expresses CML target antigens that are missing in theH-2 ^db mutation. This in vitro-isolated variant might thus be the complementary mutation to the in vivoobtainedH-2 ^db mutation.