Figure 3

The effect of surface-expressed ULBP3 on NK cell activity.

(A) The surface expression of ULBP3 on CD133⁻SW620 cells (left) or CD133⁻SW620 cells with ULBP3-siRNA transfection (right) was measured by FCM. (B–C) Effector NK cells were freshly isolated from healthy volunteers (normal NK cells) and 3 cell lines (ULBP3 siRNA-treated CD133⁻SW620, CD133⁺SW620 and CD133⁻ SW620) were used as target cells. The cytotoxicity of the NK cells was measured by LDH release after co-culture for 6 h at the indicated effector cell to target cell (E:T) ratios (B) and with or without the addition of anti-NKG2D (5 μg/ml) in co-cultures with an E:T ratio of 10:1 (C). The data are representative of results obtained from at least 3 independent experiments. The results are expressed as the mean ± SEM. *P < 0.05, **P < 0.01.