RvE1 regulates L-selectin shedding on PMNs and monocytes in whole blood. Heparinized human whole blood was incubated (30 minutes, 37°C) with increasing concentrations of RvE1 or vehicle alone, then stained with anti-CD62L (or L-selectin) for flow cytometry. CD14 was used to identify monocyte populations and PMNs were identified based on cellular morphology. (A) RvE1 stimulates L-selectin shedding in PMNs () and monocytes (■): concentration dependence. (B) Representative histograms of CD62L expression on PMNs and monocytes in whole blood after 7-minute incubation with RvE1 (30 nM). Numbers on plots are the mean fluorescence intensity of CD62L-positive PMNs or monocytes. (C) Percentage CD62L shedding from human PMNs compared with vehicle alone. Results are expressed as a percentage shedding of control mean fluorescence intensity (MFI) with the means plus or minus SEM from 3 to 6 healthy donors. **P < .005; ***P < .001.