Oxidant-mediated inhibition of ligand uptake by the macrophage XXXX receptor.

@entity274 @entity8197 @entity3624 @entity1359 @entity3913 @entity35 @entity224 @entity413 @entity855
We have investigated the effect of oxidants on ligand recognition and internalization by the macrophage @entity3913 receptor. @entity35 bone marrow macrophages were treated with increasing concentrations of @entity274 for 30 min at 37 degrees C. Fifty percent inhibition of ligand uptake was observed at 250 microM, with only 10% of control uptake remaining following exposure to 1 mM @entity274 for 30 min. Electron micrographic analysis of macrophages following @entity274 treatment showed no morphological alterations compared to untreated cells. Ligand uptake was also inhibited by the following @entity274 generating systems: @entity8197 , @entity3624 / @entity3624 oxidase, @entity413 / @entity413 oxidase, and @entity1359 -stimulated polymorphonuclear leukocytes. Inhibition could be blocked by catalase plus or minus @entity224 dismutase. Treatment of macrophages at 4 degrees C with @entity274 had no effect on ligand binding, whereas treatment with @entity274 at 37 degrees C reduced binding to 15% of control levels and decreased the number of surface receptors to one-third of control cells. @entity274 treatment inhibited ligand degradation by macrophages, but did not prevent ligand movement from the surface to the interior of the cell. In addition, ligand delivery to lysosomes was blocked by oxidant treatment. These results suggest that treatment of macrophages with reagent @entity274 or @entity274 -generating systems inhibits the normal ligand delivery and receptor recycling process involving the @entity3913 receptor. Potential mechanisms might include receptor oxidation, alterations in @entity855 levels, or membrane lipid peroxidation.
