Cytolytic activity of TAP2^−/− NK cells against tumor or EBV-transformed targets.

TAP2^−/− polyclonal NK cell populations and clones (TAP1, TAP3, TAP4, TAP5) were assessed for cytotoxicity in comparison with 2 representative clones derived from a healthy donor: CB1 (NCR^bright) and CB2 (NCR^dull). (upper panels) Effectors cells were analyzed in a cytolytic assay against the indicated tumor target cells (E:T ratio, 4:1). (lower panels) The same effector cells were analyzed against different EBV-transformed B-LCLs, including the HLA class I-negative 721.221 LCL, ST-EMO LCL, ST-EFA LCL, and LM-EBV LCL (derived from a healthy donor) (E:T ratio, 4:1). The TAP2^−/− polyclonal NK cells were assessed for cytotoxicity in the absence or in the presence of anti-HLA class I mAb (A6/136 IgM).