KIR2DL1 enhances TCR-mediated IL-2 production. (A) Jurkat, EV, and Jurkat transfectants (JK9.12, JK32, JK61) were stimulated with 1 μg/mL plate-bound anti-CD3 or control mAb for 6 hours. Culture supernatants were collected, and IL-2 production was determined by ELISA. Error bars represent the SDs of n = 10 experiments. (B) Dose-response curve for IL-2 secretion after TCR triggering with various concentrations of anti-CD3 mAb. (C) IL-2 gene expression in Jurkat, EV, and JK32 cells was assessed by quantitative RT-PCR. Results are representative of 3 independent experiments. Experimental values were normalized with respect to values for 18S RNA. (D) NKVSF mAb or control IgG was coated (or not) with anti-CD3 as in panel A, and IL-2 production was measured. (E) As in panel A, Jurkat, EV, JK32, and mutated KIR2DL1 transfectants (2ΔY/D8, 2ΔY/F11, 2ΔY/H12) were stimulated, and IL-2 production was measured. Error bars represent the SD of n = 3 experiments.