Influence of the Spleen on the Distribution of Blood Neutrophils

The influence of the spleen on the distribution of blood neutrophils was studied in rats with varying spleen sizes following transfusion of isologous 3H-dT-labelled neutrophils. The weight of the spleen correlated with the splenic neutrophil pool (r = 0.87, P less than 0.01). Alterations in spleen size did not significantly change the total blood neutrophil pool, but with increasing splenomegaly circulating and marginal neutrophils were shifted into the splenic pool. With massive splenomegaly, up to 50% of the total blood neutrophils were trapped in the spleen. These findings suggest splenic pooling of neutrophils and a shift of circulating and marginal neutrophils into the spleen proportionate to the splenic tissue present.