Key immune cell cytokines have a significant role in the expansion of CD26 population of cord blood mononuclear cells

BACKGROUND: Umbilical cord blood expresses cluster of differentiation (CD) 26, a fraction of CD34 + cells, negatively regulating in vivo homing and engraftment of hematopoietic stem cells. CD26 is highly expressed in various cells such as HSCs, immune cells, fibroblasts, and epithelial cells. It has been shown that inhibition of the CD26 on CD34 + cells improve the efficiency of transplantation of hematopoietic stem and progenitor cells. This study aimed to investigate the effect of key immune cell cytokines on CD26 expansion. MATERIAL AND METHODS: Cord blood mononuclear cells were cultured for 21 days using the stem cell factor, fetal liver tyrosine kinase 3 (Flt3) ligand (FL), interleukin (IL) 2, IL7, and IL15. Harvested cells were analyzed by flow cytometry at distinct time points. RESULTS: Our results showed that utilization of IL7 significantly improved the expression of total CD26 + cells (8.6-fold higher). When either IL2 or IL15 were added to the culture, the expression also improved 2.5-fold. The IL2 and IL7 showed significant effect on the expansion of both the CD26 + and CD26 fractions of the CD34 + cells. However, the effects of IL15 on CD26 + and CD26 -expansion were similar. CONCLUSION: Taken together, our data suggested that using IL7 causes higher proliferation of CD26 cells in comparison to that seen under other culture conditions.