Effects of IFN-γ, AA, and melittin on the levels of surface expression of CD64 in HL-60 cells. HL-60 cells were cultured for 5 days in the presence of IFN-γ (2,000 U/mL), AA (10 μmol/L), melittin (500 ng/mL), or the combination of IFN-γ (2,000 U/mL) and AA (10 μmol/L), and the combination of IFN-γ (2,000 U/mL) and melittin (500 ng/mL). Expression of CD64 was determined by flow cytometry. The data (means ± SD) represent the percentage of cells staining positive for the respective antigen obtained from six independent experiments. * Significantly different (P < .05, Student's t-test) from controls.