Heterogeneity of human natural killer recognition demonstrated by cloned effector cells and differential blocking of cytotoxicity with monoclonal antibodies

Monoclonal antibodies (MoAb) against cell surface determinants were employed to investigate the specificity of natural killer (NK)-like lysis by cloned human effector cells recognizing only K562, only HSB2, or both K562 and HSB2 target cells. MoAb W6/32.HL, TÜ39, YD1/48.HLK, and anti-Tac failed to inhibit lysis despite the expression of antigens bound by these MoAb on the effector cell surface. MoAb OKT3 moderately (⪕50%) blocked lysis of K562 and HSB2 targets, whereas MoAb 13.1, which binds T200 molecules, strongly (up to 95%) blocked lysis of K562, but not HSB2, targets. MoAb 13.1 inhibited lysis by clones which killed only K562, as well as lysis by those which killed both HSB2 and K562. In the latter case, however, only lysis of K562 was inhibited. Taken together, these results may suggest the existence of multiple receptor specificities on a single NK-active clone.