Directs effects of erythropoietin on functional properties of human monocytes/macrophages

Abstract

Aim. We studied direct effects of erythropoietin (Epo) on the function of human monocytes/macrophages (Mc/Mphs) in vitro. Methods. CD14-positive cells were isolated from human peripheral blood mononuclear cells (PBMCs) by positive magnetic separation. Mc/Mphs were cultured without or with lipopolysaccharide (LPS) for 24 hours. Membrane expression of CD14 (membrane glycosylphosphatidylinositol-bound protein), CD16 (low-affinity Fc receptor), CD119 (interferon-γ receptor), CD124 (interleukin-4 receptor), and CD197 (chemokine receptor CCR7) was evaluated by flow cytofluorometry. The content of tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), IL-6 and IL-10 in culture supernatants was determined by the enzyme immunoassay. Results. Epo was found to significantly reduce the amount of CD14⁺, CD124⁺ and CD197⁺ cells, but not CD16⁺ and CD119⁺ cells, among non-activated Mphs. Epo also detectably reduced the content of CD197⁺ cells, but not CD14⁺, CD124⁺ and CD197⁺ cells, among LPS-activated Mphs. In addition, Epo was able to moderately increase the production of interleukin-1β (IL-1β) and IL-6 by non-activated Mphs and, vice versa, to reduce the production of these cytokines by activated Mphs. At the same time, Epo did not significantly affect the Mph production of TNF-α and IL-10. Conclusion. Direction and intensity of regulatory effects of Epo on Mphs functions depend on the activation status of these cells.