Production of reactive nitrogen intermediates (RNI) by peritoneal macrophages from rats with experimental autoimmune...

Peritoneal macrophages from experimental autoimmune prostatitis (EAP) rats were examined for their capacity to secrete reactive nitrogen intermediates (RNI), measured by the release of nitrite (NO2-). Under basal conditions, there was a significant increase of NO2- secretion by cells from autoimmune rats in relation to resident cells. After stimulation in vitro with lipopolysaccharide (LPS), the NO2- production was higher in cells from autoimmune rats compared to treated and nontreated controls. The NO2- production was dependent upon the presence of L-arginine in the culture medium. The addition of L-NG-monomethyl arginine, an inhibitor of nitric oxide synthesis, to the medium reduced the amount of measurable NO2-. Kinetic studies in cells from EAP rats showed that in basal conditions there was an significant release of NO2- at day 7 of immunization that was maintained during the whole period studied. After LPS stimulation, there was a similar behavior and maximum values were reached at day 28 of immunization. These results, together with the lesion observed in the prostate gland, suggest that RNI may be of pathogenic importance in the development of early tissue inflammation and autoimmune disease of the prostate.