Effect of IFN-γ on CCR3 and CD4 expression. Monocytes were incubated with IFN-γ (500 U/mL) for 24 hours. CCR3 and CD4 expression were determined in untreated and IFN-γ–treated monocytes by flow cytometry. The shaded histograms represent control staining with isotype-matched antibodies, and the open histograms represent cells staining positive for CCR3 and CD4. Results are shown as the percentage of cells positive for CCR3 or CD4 expression and are representative of 3 cord blood samples.