Lipopolysaccharide induces rapid production of IL-10 by monocytes in the presence of apoptotic neutrophils

A Byrne, DJ Reen - The journal of immunology, 2002 - journals.aai.org
A Byrne, DJ Reen
The journal of immunology, 2002journals.aai.org
There is growing evidence that apoptotic neutrophils have an active role to play in the
regulation and resolution of inflammation following phagocytosis by macrophages and
dendritic cells. However, their influence on activated blood monocytes, freshly recruited to
sites of inflammation, has not been defined. In this work, we examined the effect of apoptotic
neutrophils on cytokine production by LPS-activated monocytes. Monocytes stimulated with
LPS in the presence of apoptotic neutrophils for 18 h elicited an immunosuppressive …
Abstract
There is growing evidence that apoptotic neutrophils have an active role to play in the regulation and resolution of inflammation following phagocytosis by macrophages and dendritic cells. However, their influence on activated blood monocytes, freshly recruited to sites of inflammation, has not been defined. In this work, we examined the effect of apoptotic neutrophils on cytokine production by LPS-activated monocytes. Monocytes stimulated with LPS in the presence of apoptotic neutrophils for 18 h elicited an immunosuppressive cytokine response, with enhanced IL-10 and TGF-β production and only minimal TNF-α and IL-1β cytokine production. Time-kinetic studies demonstrated that IL-10 production was markedly accelerated in the presence of apoptotic neutrophils, whereas there was a sustained reduction in the production of TNF-α and IL-1β. This suppression of proinflammatory production was not reversible by depletion of IL-10 or TGF-β or by addition of exogenous IFN-γ. It was demonstrated, using Transwell experiments, that monocyte-apoptotic cell contact was required for induction of the immunosuppressive monocyte response. The response of monocytes contrasted with that of human monocyte-derived macrophages in which there was a reduction in IL-10 production. We conclude from these data that interaction between activated monocytes and apoptotic neutrophils creates a unique response, which changes an activated monocyte from being a promoter of the inflammatory cascade into a cell primed to deactivate itself and other cells.
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