Fig. 2.

CD14⁺HLA-DR^−/low cells suppress NK cell function. (A) Purified NK cells were cultured in the absence or presence of different ratios of CD14⁺HLA-DR⁺ or CD14⁺HLA-DR^−/low cells as indicated. After 12 hours, K562 cells were added at a ratio of 2.5:1 (E:T) and lysis was determined by standard ⁵¹Cr-release assay (P < 0.05). Shown are cumulative results from four independent experiments. (B) NK cells were stimulated with IL-2 and cultured in the presence or absence of CD14⁺HLA-DR^−/low or CD14⁺HLA-DR⁺ cells as indicated. IFN-γ release was determined after 48 hours by ELISA. Shown are cumulative results from five independent experiments (*P < 0.05, **P < 0.001). NK cells cultured without IL-2 were used as background (arrow).