Environmental Health Perspectives 105, Supplement 5, September 1997

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Alveolar Macrophage Interaction with Air Pollution Particulates

Carroll-Ann Goldsmith, Charles Frevert, Amy Imrich, Constantinos Sioutas, and Lester Kobzik

Department of Environmental Health, Harvard School of Public Health, Boston, Massachusetts

Abstract
We applied flow cytometric analysis to characterize the in vitro response 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 found a dose-dependent increase in AM-associated right angle light scatter (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 (SR) in AM uptake of components of ROFA and CAP was identified by marked inhibition of RAS increases in AM pretreated with the specific SR inhibitor polyinosinic acid. We combined measurement of particle uptake (RAS) with flow cytometric analysis of intracellular oxidation of dichlorofluorescin. Both ROFA and CAP caused a dose-related intracellular oxidant 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 M PMA, respectively). We conclude that flow cytometry of RAS increases provides a useful relative measurement of AM uptake of complex particulates within ROFA and CAP. Both ROFA and CAP cause substantial intracellular oxidant stress within AM, which may contribute to subsequent cell activation and production of proinflammatory mediators. -- Environ Health Perspect 105(Suppl 5):1191-1195 (1997)

Key words : alveolar macrophage, flow cytometry, particles, phagocytosis, oxidant stress, scavenger receptor

This paper is based on a presentation at The Sixth International Meeting on the Toxicology of Natural and Man-Made Fibrous and Non-Fibrous Particles held 15-18 September 1996 in Lake Placid, New York. Manuscript received at EHP 26 March 1996; accepted 3 July 1997.

This work was supported by National Institute of Environmental Health Sciences grant 00002, National Institutes of Health grant HL 07118, and U.S. Environmental Protection Agency grant R824790.

Address correspondence to Dr. L. Kobzik, Dept. of Environmental Health, Harvard School of Public Health, 665 Huntington Ave., Boston, MA 02115. Telephone: (617) 432-2247. Fax: (617) 432-3468. E-mail: lkobzik@hsph.harvard.edu

Abbreviations used: AM, alveolar macrophage(s); BSS, balanced salt solution; CAP, concentrated ambient air particulate(s); DCF, dichlorofluorescein; PI, polyinosinic acid; PMA, phorbol myristate acetate; RAS, right angle light scatter; ROFA, residual oil fly ash; SR, scavenger-type receptor(s).

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Last Update: October 31, 1997