Effects of rhIFN-γ and rhGM-CSF on A23187-induced HL-60 surface Ag expression. HL-60 cells (5 × 10⁵) were cultured in a final volume of 2 mL with or without an optimal dose (180 ng/mL) of CI A23187, rhIFN-γ (1000 U/mL), or rhGM-CSF (20 ng/mL). Cells were harvested 72 hours later, stained with PE-conjugated mouse antihuman B7.2, HLA-DR, HLA-ABC, CD40, CD1a, CD83, or IgG subclass-matched control Ab, and analyzed by FACS as described in Materials and Methods. Cell viabilities (percent) at time of analysis (72 hours of treatment) are indicated below histograms for each treatment group. Histograms display staining intensity of viable (PI-excluding) cells, comparing control Ab (light lines) to specific Ab (heavy lines).