Effects of acute stress on CD62L− and CD62L+ monocyte and neutrophil numbers and CD62L expression on monocytes and neutrophils. Leukocyte numbers (1000 /μl blood) were quantified at 0 (baseline) and 6, 15, 30, 60, and 120 minutes during restraint stress. CD62L surface expression is expressed as mean fluorescence intensity (MFI) as measured on the flow cytometer. An increase in immune cell numbers relative to baseline represents mobilization of leukocytes into the blood. A decrease from peak numbers or relative to baseline represents trafficking of cells out of the blood and into tissues. Percent change relative to baseline at peak and trough is indicated. Data are expressed as means ± SEM (n=3). Statistically significant differences are indicated: * p < 0.05, and ** p < 0.01: relative to baseline (Fisher's LSD); † p < 0.05, and †† p < 0.01: relative to peak (Fisher's LSD).