B7-2 surface expression is enhanced by treatment with IFN-γ. MM6 cells were cultured for 24 hours in the presence or absence of 500 U/mL of IFN-γ. Cells were harvested and labeled for immunofluorescence analysis as described in Materials and Methods. Flow cytometry analysis was performed using an Elite flow cytometer. Closed histogram (in black) represents isotype-matched antibody control. Broken line histogram (-----) represents medium treated cells (MCFI = 16). Solid line histogram (_____) represents IFN-γ–treated cells (MCFI = 48). The MCFI values shown for medium- and IFN-γ–treated cells indicate the relative MCFI of the B7-2 staining monoclonal antibody after subtracting the MCFI of the isotype-matched antibody. Data shown are from 1 of 3 similar experiments.