Abstract
Neutrophil kinetics of acute experimental infection were studied with diisopropylfluorophosphate-(32)P labeling in 31 dogs inoculated intrabronchially with pneumococci. In vitro neutrophil labeling indicated a rapid transit time through the blood in early infections, with an elevated marginal granulocyte pool sometimes preceding an elevation of the circulating granulocyte pool. 13 hr after infection, the circulating and total blood granulocyte pools were increased but the rate of neutrophil transit through the blood was normal. During the recovery from infection there was a marked prolongation of neutrophil blood transit time, suggesting virtually complete cessation of bone marrow release of neutrophils into the blood. Labeling of neutrophils in vivo indicated an increased rate of emptying of the bone marrow storage pool proportional to the severity of infection as measured by the fever index. The change in the blood ratio of nonsegmented to segmented neutrophils was a much more accurate index of the severity of infection than the blood granulocyte concentration, correlating significantly with the fever index.