ALVEOLAR MACROPHAGE INTERACTION WITH AIR-POLLUTION PARTICULATES

We applied flow cytometric analysis to characterize the in vitro respo nse of alveolar macrophages (AM) to air pollution particulates. Normal hamster AM were incubated with varying concentrations of residual oil fly ash (ROFA) or concentrated ambient air particulates (CAP). We fou nd a dose-dependent increase in AM-associated right angle light scatte r (RAS) after uptake of ROFA (e.g., mean channel number 149.4 +/- 6.5, 102.5 +/- 4.1, 75.8 +/- 3.5, and 61.0 +/- 4.6 at 200, 100, 50, and 25 mg/ml, respectively) or CAP. A role for scavenger-type receptors (SH) in AM uptake of components of ROFA and CAP was identified by marked i nhibition of RAS increases in AM pretreated with the specific SR inhib itor polyinosinic acid. We combined measurement of particle uptake (RA S) with flow cytometric analysis of intracellular oxidation of dichlor ofluorescin. Both ROFA and CAP caused a dose-related intracellular oxi dant stress within AM, comparable to that seen with phorbol myristate acetate (PMA) (e.g., fold increase over control, 6.6 +/- 0.4, 3.6 +/- 0.4, 4.6 +/- 0.5, 200 mg/ml ROFA, 100 mg/ml ROFA, and 10(-7) nil PIV;A , respectively). We conclude that flow cytometry of RAS increases prov ides a useful relative measurement of AM uptake of complex particulate s within ROFA and CAP. Both ROFA and CAP cause substantial intracellul ar oxidant stress within AM, which may contribute to subsequent cell a ctivation and production of proinflammatory mediators.