Abstract
The effects of two multicomponent pollutant atmospheres on the surface receptors (FcR) and phagocytic activity of rat pulmonary alveolar macrophages have been studied. FcR are crucial for the macrophages to become cytotoxic against target cells. The atmospheres were composed of pollutants that are prevalent in the South Coast Air Basin of southern California. Rats were exposed nose-only to a 7-component oxidant-and sulfate-containing atmosphere for 4 h/d for either 7 or 21 consecutive days. In another experiment rats were exposed 5 h/d for 5 consecutive days to another pollutant combination--acid droplets plus carbon-containing dilute diesel engine exhaust. In both experiments matched rats were exposed nose-only to purified air to be used as controls. Each of the atmospheres studied significantly reduced FcR activity for at least 3 d following the exposure, with the group of rats exposed to the 7-component atmosphere for 21 d exhibiting the most pronounced effect. Macrophages from rats exposed to the diesel exhaust plus acid atmosphere and the 7-component atmosphere for 7 d had significantly reduced phagocytic activity for at least 3 d postexposure, while the macrophages from rats exposed to the latter atmosphere for 21 d had phagocytic activity near control values. The decrease in phagocytosis and inhibition of FcR of macrophages suggests an impairment of macrophage function that probably renders the host vulnerable to bacterial and/or viral infections.
Highlights
People living in areas heavily impacted by vehicular and stationarysource air emissions are exposed to a large variety of airborne particles and gases
Air pollution in the South Coast Air Basin of southern California consists of a complex mixture of chemical species, which include oxidant products such as ozone (O3) and nitrogen dioxide (NO2), acidic products such as nitric acid (HNO3), sulfuric acid (H2SO4) and associated sulfates, insoluble particles, sulfur dioxide (SO2), free radicals, and other species (Finlayson-Pitts and Pitts, 1986)
In such samples ion analysis indicates that nitrate ion (NO3~) and sulfate ion (SO4~) are present in ratios (NO3"7 SO4~ = 2) that are consistent with the relative emission rates of nitrogen oxides (NOX) and SO2 (Waldman et al, 1982; Brewer et al, 1983)
Summary
People living in areas heavily impacted by vehicular and stationarysource air emissions are exposed to a large variety of airborne particles and gases. The seven-component mixture contains O3, NO2, SO2, soluble sulfate aerosols, trace metal ions (Fe3+ and Mn2+), and insoluble iron oxide (Fe2O3) particles (as a surrogate for insoluble atmospheric particles) Acidic reaction products such as particulate bisulfate ion (HSO4~) and HNO3 vapor formed by the interactions of the gases and particles that make up the atmosphere are present in the exposure atmosphere. The resident macrophages in the lung defend against both particulate environment pollutants and pathogenic microorganisms They possess distinct receptors (FcR) on their surfaces for the Fc portion of immunoglobulin (IgG) which help in the recognition of foreign particles (Gaafar and Doyle, 1971). The 7 or 21 d of daily exposures to the 7-component atmosphere were intended to represent subchronic exposure to a complex air pollution mixture that contains both sulfate and oxidant and generates acids as well as nitrate radical (Platt et al, 1980). A pilot exposure to ozone was performed in order to evaluate the endpoints following a single acute exposure to an atmosphere that has been demonstrated in our laboratory to affect respiratory tract permeability (Bhalla et alv 1986), alter upper and lower respiratory tract particle clearance rates (Kenoyer et al, 1981), and produce pulmonary lesions (Mautz et alv 1985)
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