Free radicals play an important role in inflammation. We found that reactive oxygen intermediates (ROI) inhibit interleukin-1β (IL-1β) binding on human myelomonocytes. Production of superoxide anion (O2/-) by Xanthine (X) and Xanthine-Oxidase (XO) or NADPH caused a reduction (48% ± 15% in 25 experiments) in the IL-1β binding of polymorphonuclear cells (PMN) and monocytes that was inhibited by superoxide dismutase (SOD). Hydrogen peroxide (H2O2) was only active on monocytes and this effect was prevented by catalase. O2-induced loss of IL-1β binding on PMN reached half maximum at 5 minutes and peaked after 30 minutes. The reduction of IL-1β binding was due to a reduction of IL-1β receptors (R) on PMN surface without any change in affinity. ROI-induced reduction of surface IL-1R was not caused by receptor internalization, but rather by the release of a soluble form (45 kD) of the type II decoy R. The action of ROI on IL-1 binding was selective because major histocompatibility complex class I, CD18 and CD16 were unaffected. The O2/--induced release of IL-1 decoy R was not affected by protein synthesis inhibitors, but was partially blocked by protease inhibitors. Release of the IL-1 type II decoy R might represent one mechanism by which ROI antagonize and limit the proinflammatory effects of IL-1.
|Number of pages||5|
|Publication status||Published - Mar 1 1996|
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