The release of PMN^BrdU into the circulation after IV IL-8 (2.5 μg/kg) (n = 4) or saline (n = 4). BrdU was infused 24 hours before the IL-8 was administered. At time 0, the percentage of PMN^BrdU in the circulation was less than 2% (A). IL-8 induced a rapid increase in the percentage of PMN^BrdU in the circulation, which remained higher than the controls for 90 minutes (*P < .05 v control). (B) Shows the absolute number of PMN^BrdU in the circulation. After IV IL-8, the number of circulating PMN^BrdU increased and peaked at 60 minutes, then gradually declined to baseline levels at 180 minutes. The control group showed no change in either the percentage or the number of PMN^BrdU during the 180-minute study period. Values are mean ± SEM.