Uniform Combretastatin-induced Effect on Monocytes and Neutrophils in Peripheral Blood but Not in Tumors

Abstract

Background/aim: Combretastatin A-4 phosphate (CA4P) is a vascular-disrupting agent which affects the level of circulating neutrophils. Since tumor-associated macrophages and neutrophils may collaborate, we compared the effect of CA4P treatment on monocytes/macrophages and neutrophils.

Material and methods: CDF1 mice with a C3H mammary carcinoma foot tumor were injected intraperitoneally with CA4P. Blood samples were taken and tumors excised at various time-points after treatment. Circulating monocytes and granulocytes were detected by flow cytometry and the tumor levels of these cell types was estimated immunohistochemically.

Results: CA4P induced similar oscillating effects on the level of circulating monocytes and of neutrophils, with an initial decrease followed by an increase and a return to control levels at 6-h and 24-h, respectively. In tumors, only the macrophage level decreased significantly after treatment.

Conclusion: CA4P induced similar changes in the level of circulating monocytes and neutrophils, but only affected the fraction of macrophages significantly.

Keywords: Combretastatin; monocytes; neutrophils; tumors.