Does iron modulate cytokine production by desferrioxamine treated mononuclear cells?

Iron is an essential element for maintaining the normal function of cellular and multicellular organisms and it is closely associated with inflammation and immunity. Macrophages and lymphocytes play an important role in its homeostasis. Hereby we have evaluated cytokine production by iron depleted and iron supplemented human peripheral blood mononuclear cells (PBMC) from healthy adult donors. Non-stimulated or stimulated PBMC (lipopolysaccharide-LPS or phorbol-myristate acetate-PMA and ionomycin) were incubated for 24 h without or with desferrioxamine (DFO) and the quantity of TNFα, IL-1β, IL-6, IFNγ, IL-2, IL-10 and IL-1ra in the supernatants was evaluated using ELISA kits. In addition, cytokine levels were determined in supernatants of cultures to which DFO was added for 2 h followed by 24 h of incubation with iron. The secretion of IL-1β, IL-6 and IL-1ra by non-stimulated PBMC and that of IL-1β by LPS-stimulated cells was dose-dependently enhanced following incubation with increasing concentrations of DFO between 25 and 100 µM. On the other hand LPS-induced production of IL-10 and PMA/ionomycin stimulated IL-2 and IFNγ secretion was dose dependently reduced. The inhibited IFNγ, IL-2 and IL-10 secretion by stimulated PBMC caused by DFO was reversed after incubation with iron at concentrations similar to those in human serum. However, the inhibition of LPS-induced IL-1ra or IL-1β production induced by DFO was not affected by iron supplementation. The results of the study underline the importance of intra and/or extracellular iron concentration and DFO for the release of inflammatory cytokines by human peripheral blood mononuclear cells.