NITROGEN DIOXIDE-INDUCED REACTIVE OXYGEN INTERMEDIATES PRODUCTION BY HUMAN ALVEOLAR MACROPHAGES AND PERIPHERAL-BLOOD MONONUCLEAR-CELLS

Alveolar macrophages located on the alveolar surface have contact with air pollutants. We evaluated the dose-dependent effect of nitrogen di oxide exposure on the oxidative metabolism of alveolar macrophages and peripheral blood mononuclear cells by measuring the spontaneous and s timulated reactive oxygen intermediates production. Alveolar macrophag es or peripheral blood mononuclear cells were placed on a polycarbonat e membrane, which was in direct contact with the surface of a nutrient reservoir. The cells were exposed to nitrogen dioxide during differen t periods of time, varying between 30 and 120 min at concentrations ra nging from 0.1 to 0.5 ppm. Exposure of alveolar macrophages to nitroge n dioxide for 30 min yielded a dose-dependent stimulation of reactive oxygen intermediates generation of 1.7- to 2.9-fold of control. An 120 -min exposure to nitrogen dioxide at concentrations between 0.1 and 0. 5 ppm resulted in a similar reactive oxygen intermediates production o f about 1.9- to 2.2-fold of control at all concentrations tested. The nitrogen dioxide exposure to peripheral blood mononuclear cells yielde d identical results. These experiments demonstrate that alveolar macro phages and peripheral blood mononuclear cells become activated by nitr ogen dioxide and that concentrations up to 0.5 ppm nitrogen dioxide in duce an increase in reactive oxygen intermediates production after 30 to 120 min exposure of the cells.