Neutrophil Kinetics after Acute Hemorrhage

Abstract

Mice were bled and at intervals thereafter, blood neutrophil concentration, blood band/segmented neutrophil ratio and total number of neutrophils per humerus were determined. Within the first 3 hr after hemorrhage maximal increase in the circulating blood neutrophil concentration was observed. However, this was not accompanied by a significant increase in band/seg ratio in the blood nor was it accompanied by a significant decrease in marrow neutrophils. Therefore, the early neutrophilia after hemorrhage probably reflects a shift of intravascular neutrophils from the marginal to the circulating pool. However, between 3 and 6 hr after hemorrhage there was a striking increase in band/seg ratio in blood and a decrease in total marrow neutrophils. Thus, following the initial pseudoneutrophilia caused by demargination, an increase in the rate of release of marrow neutrophils occurred resulting in a decrease in marrow neutrophils and an increase in the band/seg ratio in the blood. It is suggested that this increase in release rate is triggered by a decrease in the size of the marginal pool.