Alloreactivity mediated by KIR2DS1⁺ NK cells against C1/C2 Bw4/Bw4 target cells. Analysis of the cytolytic activity of different groups of KIR2DS1⁺ NK-cell clones (derived from donor P61) against mDCs or PHA blasts derived from the C1/C2 Bw4/Bw4 donor SC either in the absence or in the presence of mAb to the indicated molecules. These KIR2DS1⁺ clones coexpressed either NKG2A or KIR3DL1 or KIR2DL2/L3. The E:T ratio used against mDCs was 15:1 whereas that used against PHA blasts was 20:1. Average of 3 independent experiments and SD (mean ± SD) are indicated.