Human Umbilical Vein Endothelial Cells Support Interleukin-3- and Interleukin-5-Induced Eosinophil Differentiation from Cord Blood CD34+ Cells

Background: Human umbilical vein endothelial cells (HUVEC) are an important source of hematopoietic cytokines, and interleukin-3 (IL-3)- and IL-5-induced eosinophil differentiation from CD34+ cells has been observed. To show the supportive effects of endothelial cells on eosinophil differentiation, we examined the effects of cocultured HUVEC on IL-3 and IL-5-induced eosinophil differentiation from human umbilical cord blood CD34+ cells. Methods: CD34+ cells were obtained from the heparinized umbilical vein blood of 10 volunteers using a CD34-conjugated magnetic bead positive direct selection procedure. With HUVEC in Transwell, CD34+ cells were then cultured for 14–28 days. In neutralizing experiments on HUVEC-derived cytokines, antibodies to both stem cell factor (SCF) and granulocyte/macrophage colony-stimulating factor (GM-CSF) were added to the cell cultures. Results: Cocultured HUVEC upregulated IL-3 and IL-5-induced eosinophil differentiation from CD34+ cells on day 28 of culture by 75.0%. The eosinophilopoietic effect of HUVEC was significantly only when the cells were present in the culture from day 15 to day 28. Addition of anti-SCF antibody or anti-GM-CSF monoclonal antibody to the culture significantly suppressed HUVEC-combined IL-3- and IL-5-induced eosinophil differentiation on day 28 of culture by 49.2 and 55.0%, respectively. Conclusions: These results indicate that several cytokines including GM-CSF and SCF from HUVEC promote IL-3- and IL-5-induced eosinophil differentiation from CD34+ cells.