Cytotoxicity and specificity of anti-SK and anti-OF CTL lines.

(A) The cytotoxicity of both CTL lines was tested in a 4-hour⁵¹Cr release assay against primary SK or OF cells at several effector-to-target ratios. (B) Inhibition of LAK or NK activity (or both) of the CTL lines by cold target inhibition using K562 cells. Increasing numbers of unlabeled K562 cells were added to⁵¹Cr-labeled SK or OF target cells at an effector-to-hot target ratio of 2:1. (C) HLA restriction of cytotoxicity. HLA class I or HLA class II was blocked on the target cells using monoclonal antibodies in the presence or absence of a 50-fold excess of K562 cells. Cytotoxicity was performed at an effector-to-target ratio of 1:2.