Characteristics of pulmonary macrophages lavaged from hamsters exposed to iron oxide aerosols
Kavet, R.I.; Brain, J.D.; Levens, D.J.
Laboratory Investigation; A Journal of Technical Methods and Pathology 38(3): 312-319
1978
ISSN/ISBN: 0023-6837 PMID: 633855 Document Number: 137815
Syrian golden hamsters breathed an Fe2O3 aerosol for 3 h (mass median aerodynamic diameter = 0.15 .mu.m.; 274 .+-. 18 (SD) mg per cm3). To inhibit potential recruitment of mononuclear phagocytes into alveoli, some animals received hydrocortisone acetate i.m. (0.3 mg/g of body wt) 18 h before exposure. In vitro phagocytic rates and intercellular phagocytic heterogeneity of lavaged pulmonary macrophages were visually assayed after 4 min of incubation of pulmonary macrophages with 2-4 .mu.m albumin-coated spheres (17 .times. 106 particles/ml). Fe2O3 stimulated phagocytic rates and expansion of macrophage volumes and provoked a recruitment of mononuclear phagocytes into the lavageable pool of cells. These effects were all prominent 24 h after aerosol exposure. Stimulation of phagocytosis was greatest at 3 days postexposure (.uparw. 66%) and still evident at 11 days. Inflammation, as measured by granulocytic influx, peaked at 24 h and was gone at 3 days. Hydrocortisone blocked aerosol-induced macrophage recruitment, suppressed the inflammatory response and depressed phagocytic rates. Despite this depression, Fe2O3 stimulated an increase in the phagocytic rates of pulmonary macrophages harvested from steroid-treated animals. Neither Fe2O3 nor hydrocortisone, alone or in combination, importantly affected heterogeneity. Aerosol exposure may activate pulmonary macrophages. This activation can occur even when steroids minimize the addition of new cells to the resident pool.