KIR2DL2 does not inhibit TCR-mediated cytotoxicity. (A) The level of KIR2DL2/2DL3/2DS2 expression on CD4⁺CD28^– T cells and CD56⁺ NK clones were examined by FACS analysis. (B) KIR⁺ CD4⁺CD28^– T-cell clones were tested for the presence of KIR2DL2, KIR2DL3, and KIR2DS2 mRNA by PCR. (C) The ability of KIR2DL2 to inhibit either T-cell–mediated (top panel) or NK cell–mediated (bottom panel) cytotoxicity was examined in a 4-hour cytotoxicity assay against anti-CD3 (•) and anti-CD3 + anti-KIR2DL2/2DL3/2DS2 (○) or anti-CD16 (▪) and anti-CD16 + anti-KIR2DL2/2DL3/2DS2 (□)–labeled P815 cells. Both anti-CD3 and anti-CD16 were tested over a wide dose range, and selected concentrations are shown. (D) The effect of KIR2DL2 on CD4⁺CD28– T cells on granule exocytosis was measured in 4-hour BLT release assay against either anti-CD3 and anti-CD3 + anti-KIR2DL2-coated P815 cells (left panel) or SEB-coated 721.221 and 721.221/HLA-Cw3 cells (right panel). Results are shown as mean ± SD of triplicate cultures.