Adherence influences monocyte responsiveness to interleukin-10.

We studied the effects of adherence on the properties of interleukin (IL)-10 on monocyte-enriched peripheral blood mononuclear cells. We found that the decrease of CD11b expression induced by IL-10 was enhanced by adherence. Toll-like receptor (TLR)2 and TLR4 mRNA, as well as TLR4 surface expression, were significantly up-regulated by IL-10 in adherent cells. The absence of adherence prevented the inhibitory effects of IL-10 on lipopolysaccharide-induced tumor necrosis factor (TNF) and granulocyte-colony stimulating factor production and increased IL-1beta production and soluble TNF receptor II release in IL-10-pretreated cells. Similarly, the absence of adherence amplified the enhancement of phagocytosis induced by IL-10. Tyk2 and signal transducer and activator of transcription 3 (STAT3) phosphorylation and suppressor of cytokine signaling 3 (SOCS3) expression were induced by IL-10 in both conditions, but a longer activation and/or expression were observed in adherent monocytes. Finally, heme oxygenase-1, an anti-inflammatory molecule, was induced by IL-10 in adherent monocytes, whereas its expression remained low in nonadherent cells. Altogether, these data illustrate that adherence modulates the properties and the anti-inflammatory effects of IL-10.