Biochemical and ultrastructural evaluation of the interaction between IgG immunecomplexes and polymorphonuclear leukocytes: effect of natural antioxidants.

The generation of reactive oxygen species (EROs) by polymorphonuclear leukocytes (LPMNs) during phagocytosis plays a key role in the organism defense against invading microorganisms. However, in some diseases the immune complexes deposition occurs, that causes an increase in the production and release of EROs. Consequently, the host tissue is damaged. In this work we studied the effect of natural compounds (quercetin and 7-allyloxycoumarin) on EROs generation by rabbit (LPMNs) stimulated with immunecomplexes (IC) of chicken egg albumin (antigen) and class G immuneglobulins (IgG) - ICIgG. The EROs production was measured by chemiluminescence assay (OL) enhanced by luminol (QL(lum)) or by lucigenin (QL(luc)). The interaction between ICIgG (conjugated with colloidal gold) e LPMNs, mediated by Fcgamma membrane receptor, was observed by transmission electron microscopy. The results indicated that the studied compounds inhibited QL(lum), and QL(luc). They also suggest that such effects are not related to phagocytosis inhibition, as observed by the electron microscopy assay.