IFN-γ induces K562 cells to rapidly express membrane PAF receptors.

K562 and Daudi cells were stimulated with 300 U/mL of human IFN-γ for 30 minutes and for 1, 2, and 4 hours and were analyzed by flow cytometry for PAF receptor membrane expression. U937 cells were used as positive controls. The background signal is shown (dotted lines). Inset numbers indicate the percentage of cells expressing the protein and the mean fluoresence intensity at the indicated times. Regarding the capacity of tumor cells to express membrane PAF receptor, K562 cells were IFN-γ sensitive; Daudi cells, IFN-γ resistant.