KIR2DL3 expression on T cells inhibits MLR. (A) The proliferation of splenic T cells from Tg-KIR2DL3 and WT mice of H-2^b haplotype in response to allogeneic (H-2^k) stimulator spleen cells was assessed by (³H)thymidine incorporation after 3 days of MLR. (B) IL-2 secretion in the supernatant of MLR at day 3 was assessed by measuring the proliferation of the IL-2–dependent CTLL-2 cell line. Data represent the mean values ± standard deviation of triplicate determinations of 1 out of 3 representative experiments. (▪) None; () WT H2^b; (▨) WT H2^k; () Tg-HLA-Cw3 H2^k.