Abstract
Summary
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.
A dose-response relationship between the degree of hemorrhage and the number of neutrophils removed as compared to the number of neutrophils flushed from the bone marrow into the blood was constructed. The relationship between the total amount of blood removed and number of neutrophils flushed was somewhat better than was the relationship between the total number of neutrophils removed from the blood and the number of neutrophils flushed from the bone marrow. It was therefore suggested that the acceleration of neutrophil release rate from bone marrow to blood was primarily a function of changes in intravascular tone rather than a function of actual loss of neutrophils from blood vessels.
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