Flow cytometric analysis of B7-1 and B7-2 expression on GM-CSF/IFN-γ–treated PMN. PMN were cultured for 44 hours in the absence or presence of 100 U/mL GM-CSF/IFN-γ before staining. Open peaks represent staining with isotype controls. Closed peaks represent staining with HLA-DR, B7-1, B7-2, or FcγRI-specific antibodies. Antibody binding to PMN cultured in the absence of GM-CSF/IFN-γ had the same MFI as the isotype control. Flow cytometric histograms represent 5,000 to 10,000 gated PMN.