Abstract: Calf spleen extract (CSE) has been clinically used as an adjuvant agent in malignant tumor therapy. It can improve the physical status of patients. However, its mechanism of action remains relatively unclear. In this study, we investigated the effect of CSE on leucopenia in mice and on promyelocytic leukemia cells (HL60). CSE in 10 mL/kg (2.5 mg bioactive polypeptides and 190 μg ribose/mL) significantly increased leukocyte numbers in leucopenia mice. The effect on neutrophil numbers, among all leukocytes, was the most evident. CSE stimulated the proliferation of bone marrow cells in vitro and decreased the GM-CSF level in serum. In addition, CSE significantly reduced the viability of HL60 cells, decreased the production of lactate and adenosine triphosphate (ATP) of these cells. CSE induced the apoptosis and S-phase arrest in HL60 cells. In conclusion, CSE can enhance leukocyte numbers, which may be attributed to its direct stimulatory effect on bone marrow cells. CSE is an inhibitor of promyelocytic leukemia cell viability, which may be attributed to the induction of the apoptosis, the arrest of cell cycle and the inhibition of the glycolysis of cells.

Key words: Leucopenia, Glycolysis, Apoptosis, Cell cycle arrest, Calf spleen extract