LUMINOL-ENHANCED CHEMILUMINESCENCE AFTER IN-VITRO EXPOSURES OF RAT ALVEOLAR MACROPHAGES TO OIL FLY-ASH IS METAL-DEPENDENT

Epidemiologic studies have associated exposures to air pollution parti cles with human mortality. Much of this excess mortality is attributed to a respiratory injury. It has been postulated that such injury afte r particle exposure can result from the capacity of these dusts to cat alyze the generation of oxygen-based free radicals. We tested the stud y hypotheses (1) that oxidant production by rat alveolar macrophages i ncreases with exposures to an emission source air pollution particle ( i.e., an oil fly ash), (2) that this elevation in radical generation i s dependent on the concentrations of metal associated with the oil fly ash and available to support electron transport, and (3) that increas er in the cellular oxidant formation can be simulated by both soluble metal salts and metal complexed to insoluble carboxylate functionalize d latex beads. Luminol-enhanced chemiluminescence was measured in reac tion mixtures that included rat alveolar macrophages (0.5-1.0 x 10(6) cells/ml), 0.1 mM luminol, 1% bovine serum albumin, and either oil fly ash, iron sulfate, nickel sulfate, vanadyl sulfate, or latex particle s with iron, nickel, and vanadyl cation groups complexed to the surfac e. In vitro exposure of the cells to the oil fly ash significantly inc reased chemiluminescence, while inclusion of deferoxamine and hydroxyl radical scavengers diminished the signal. Solutions of metal sulfates similarly elevated chemiluminescence in a dose- and time-dependent ma nner. Finally, latex beads with complexed iron, nickel, and vanadyl ca tion groups significantly augmented the signal again in a dose- and ti me-dependent manner. We conclude that (1) the in vitro generation of o xidants by rat alveolar macrophages increases after exposures to an em ission source air pollution particle, (2) these elevations in the prod uction of oxygen-based free radicals alter exposure of phagocytes to a n air pollution particle can be metal dependent, and (3) solutions of metal sulfates and latex particles with complexed metals similarly aug ment chemiluminescence by alveolar macrophages.