On the mechanism of post-splenectomy leukocytosis in mice

Background Increased number of peripheral white blood cells (PWBCs) has been noted after removal of the spleen. Design To clarify the possible mechanisms by which splenectomy affects the PWBC number, the percentage of apoptotic PWBCs, the number and migration rate of peritoneal cells, as well as the H-3-TdR incorporation into PWBCs, were examined in splenectomized, sham-operated and control mice. In addition, the effect of control plasma injected to splenectomized animals on the number of PWBCs was examined. Results One and two months after splenectomy the PWBC counts significantly increased, whereas the percentage of apoptotic PWBCs and the number of cells in the peritoneal cavity decreased in comparison with that of the control and sham-operated mice. Seventeen days after injection of carboxy-fluorescein diacetate succinimidyl ester (CFSE)-labelled peritoneal cells into the peritoneal cavity of the animals, their number was significantly higher in the peripheral blood and lower in the peritoneal cavity of the splenectomized animals in comparison with that of the control and sham-operated mice. Injection of control plasma into the splenectomized mice prevented the development of postsplenectomy leukocytosis. Finally, H-3-TdR incorporation into nonstimulated and Con A stimulated PBMCs from the splenectomized mice was higher as compared with cells from the control and sham-operated mice. Conclusions The results of the study present several mechanisms that may clarify the cause of postsplenectomy leukocytosis.