The effect of CD63 deficiency on P-selectin-dependent leukocyte rolling and neutrophil migration in vivo. Surgically-induced leukocyte rolling flux was measured in WT littermate control (open bars) and CD63^−/− (closed bars) mice before and after administration of P-selectin antibody (RB40.34, 30 μg/mouse; A). Results are presented as mean ± SEM for n = 9-12 venules from at least 4 mice per group. ***P < .001 compared with wild type rolling before anti-P-selectin antibody administration; NS = not significantly different. Peritoneal neutrophil influx in CD63^−/− (●) or WT mice (○) after thioglycollate (3%, 2 mL/mouse, IP) was also measured (B). Peritoneal lavage was performed at the times indicated and the number of neutrophils present in the lavage fluid was determined from total and differential cell counts. Two mice of each genotype were used for 0 hour time point and 6 mice of each used for all other time points. Data are shown as mean ± SEM ***P < .001 compared with wild- type control at the same time point.