Figure 1.

2B4 and NTB-A-mediated cytotoxicity is dependent on the expression of SAP, but not EAT-2 in primary human NK cells. IL-2-activated primary human NK cells were transfected with control siRNA, siRNA against SAP, against EAT-2 or both. (A) The knockdown was confirmed 48 h later by Western blotting of whole cell lysates. The numbers below the lanes indicate relative signal intensity. The values were normalized to the respective actin signal and the value for the control siRNA sample was set to 1. (B) The functional consequence of the decreased expression of the adapter molecules was tested in a 4 h ⁵¹Cr-release assay against P815 cells in the presence of control Ab, or antibodies against 2B4, NTB-A, or NKG2D. Results shown are from four independent experiments. Plotted is the specific lysis at an E/T ratio of 5/1 corrected by subtracting the lysis observed in the presence of control Ab for each experiment. The bars represent the mean value. Statistical significance of the reduced lysis compared to control siRNA-transfected cells was calculated using One-Way ANOVA and Dunnett's post test (^*indicates p < 0.05).