Cross-reactivity of cytotoxic T-lymphocyte antigen-binding receptors immune to antigens of the H-2 system.

Anti-B10 D2 (anti-KbDb) cytotoxic T lymphocytes (CTL) and monospecific anti-Kk and anti-Dd CTL, separated from their mixture in anti-A B10 lymphocytes and concentrated with the absorption-elution technique on the macrophage monolayers of various genotypes, gave rise to cross-lysis of third-party target cells. Anti-B6 R101 (anti-Kb) CTL, which display a cross-lysis of mutant Kbd (M505) and Kba (Hzl) target cells, were separated into two fractions, one of them being able and the other unable to adhere to the cell monolayer of the particular mutant. The fraction of anti-Kb CTL adherent to Kba antigen was isolated by elution from the Hzl cell monolayer. These anti-Kba CTL and CTL eluted from the B6 cell monolayer displayed a considerably higher cytotoxic effect on B6 than on Hzl target cells. This difference was not due to lower sensitivity of Hzl targets to lysis. The findings indicate that anti-Kb CTL are homogeneous in the specificity of their receptors. The H-2 molecule is presumed to bear a single CTL determinant only, which induces a CTL clone or a group of clones homogeneous in specificity but heterogeneous in the affinity of its receptors.