EFFECT OF NITRIC-OXIDE DONORS ON NEUTROPHIL RESPONSES INDUCED BY IMMUNE-COMPLEXES

The present study characterizes the effect of two nitric oxide (NO) do nors, S-nitrosoglutathione (GSNO) and sodium nitroprusside (SNP), on t he ability of neutrophils to perform different responses triggered by immune complexes (IC). Pretreatment of neutrophils with either GSNO or SNP exerted a biphasic action on antibody-dependent cellular cytotoxi city (ADCC) performed against erythrocytes (E) coated with IgG antibod ies (IgG-E), depending on the amount of IgG employed. While with high amounts of antibodies ADCC was markedly inhibited, at low amounts of a ntibodies it was significantly increased. Both effects were prevented by haemoglobin, a NO scavenger. Moreover, these effects were reproduce d by the cell-permeable analogue of cGMP, dibutyryl cGMP (Bt(2)cGMP). Other neutrophil functions triggered by IgG-E were also explained. It was found that NO donors did not affect either the phagocytosis of IgG -E or the emission of chemiluminescence (CL). Finally, neutrophil func tions triggered by soluble IC (sIC) and precipitating IC (pIC) were an alysed. It was observed that NO donors did not modify either cytotoxic ity performed towards non-sensitized target cells or CL emission. The significance of these results is discussed.