KIR2DL2 inhibits TCR-mediated IFN-γ production and cell proliferation. (A) KIR2DL2⁺ T cells were stimulated with SEB-coated 721.221 or 721.221/HLA-Cw3 target cells. Gene expression was profiled at 0, 4, and 24 hours. Only those genes that showed at least a 3-fold increase in expression after activation were selected, and the expression levels of these genes under the 2 culture conditions were compared. KIR2DL2 engagement by HLA-Cw3 reduced the stimulation-induced up-regulation of the majority of genes. (B) Induction of IFN-γ was found to be strongly inhibited by gene array. To confirm this result, KIR2DL2⁺ T cells were incubated with anti-CD3 + IgG (150 ng/mL) or anti-CD3 + anti-KIR2DL2 (150 ng/mL) coated P815 cells (top panel); or with SEB-coated 721.221 or 721.221/HLA-Cw3 target cells (bottom panel) for 48 hours. IFN-γ in the supernatant was quantified by ELISA. Results are shown as mean ± SD of triplicate cultures representative of 5 experiments. (C) CFSE-labeled KIR2DL2⁺ T cells were incubated with SEB-coated 721.221 or 721.221/HLA-Cw3 target cells for 5 days. The percentage of T-cell proliferating was determined by FACS analysis. Results are shown as mean and SD of triplicates representative of 3 experiments.