1Department of Immunology, Faculty of Medical Science, Tarbiat Modares University
2Department of Regenerative Medicine, Royan Institute for Stem Cell Biology and Technology
3Department of Immunology, School of Medicine, Tehran University of Medical Sciences
4Cell and Molecular Research Center, Iran University of Medical sciences , Tehran, Iran
Background: Tumor necrosis factor alpha (TNF-α) is a primary mediator of immune regulation and might be required in the early stages of DC development from CD34+ cells. However, details of optimal timing of exposure to TNF-α in DC development process in monocytes or non-purified hematopoitic cells are still lacking and clear benefits of this approach to the development of DCs remain to be validated. Objective: To evaluate the effect of early and late exposure to TNF-α on DC devel-opment from non-purified cord blood mononuclear cells. Methods: To define the ef-fects of early exposure to TNF-α on cord blood mononuclear cells, we cultured UCB-MNC in the presence of SCF, Flt3L, GM-CSF and IL-4 for 14 days and matured them for an extra 4 days. TNF-α was added on day 0, 7 and 14 in TNF-α + group, and only on day 14 in TNF-α - group where it was used only as a maturation factor. Results: Immediate exposure to TNF-α was shown to: (1) enhance the survival of cells in the first week of culture; (2) produce mature DCs with higher maturation markers (CD80, CD83, CD86 and HLA-DR); and (3) increase secretion of IL-12 by mature DCs. In contrast, delayed exposure to TNF-α stimulate mature DCs with less purity producing a high level of IL-10 and a low level of IL-12. Conclusion: We developed a simple, easy and cost effective method to generate DCs from non-fractionating mononuclear cells in this study. Also we confirm the presence of a large number of functional DCs under inflammatory conditions, where local concentrations of TNF-α were high.