Circulating neutrophil counts in the arterial and venous blood during and after infusion of complement fragments. The counts between 0 and 20 minutes are shown in (A), and (B) shows the counts for the entire 2-hour duration of the experiment. The venous counts (□) decreased more slowly than the arterial counts (○) in the first 2 minutes of the infusion. Both arterial and venous counts were decreased at 2 to 4 minutes. The neutrophil counts in the arterial blood samples remained low throughout the entire infusion. However, the counts in the venous samples began to increase by 7 minutes, and continued to rise throughout the infusion. After the infusion was stopped, neutrophil counts in both arterial and venous blood increased similarly, reaching peak values that were twofold to threefold above baseline values by 45 minutes (30 minutes after the infusion was stopped). The counts returned to baseline values by 90 minutes. *Significantly greater than the neutrophil counts in the arterial blood, P < .05.