LPS-, TNF-–, and IL-8–induced CXCR downregulation is not due to cell death. Purified peripheral blood PMNs were incubated for 3 hours at 37°C in media alone (RPMI/10% fetal calf serum) or stimulated with LPS (100 ng/mL), TNF- (50 ng/mL), IL-8 (500 ng/mL), or dexamethasone (100 mmol/L). Propidium iodide staining and CXCR1 staining was measured using two-color parameter flow cytometry. Data are represented as contour plots with the x-axis indicating CXCR1 fluorescence intensity measured on a log₁₀ scale and the y-axis indicating propidium iodide fluorescence intensity measured on a log₁₀ scale. MFI values for CXCR1 staining are indicated in the bottom right panel of each contour plot. MFI values for propidium iodide staining are indicated in the top right panel of each contour plot. Similar data were observed for CXCR2 expression.