SAWDUST-INDUCED INFLAMMATORY CHANGES IN RAT LUNG - EFFECTS ON ALVEOLAR AND INTERSTITIAL-CELLS IN RELATION TO TIME

Exposure to sawdust and its contaminants, e.g., terpenes, may cause re spiratory tract and lung parenchymal inflammation. To monitor these ch anges over time, Sprague-Dawley mts were exposed at one occasion to 2. 5 mg sawdust or saline by intratracheal instillation. Flow cytometry a nalyses were done on bronchoalveolar lavage (BAL) cells. Lung tissue s pecimens were analyzed histologically and immunohistochemically. After one week, the number of BAL polymorphonuclear leukocytes was increase d (P < 0.05, N = 8), followed at six weeks by increases of macrophages and lymphocytes (both P < 0.01, N = 8). Enhanced expressions of class II antigens and complement receptors on macrophages after one week we re even more pronounced at six weeks, indicating cellular activation. The BAL findings, also including increased (P < 0.001, N = 8) concentr ations of hyaluronan with progressing changes over time, confirmed the signs of inflammation, as did the histological analysis of the lung t issue specimens with an accumulation of polymorphonuclears, macrophage s, and hyaluronan in the interstitium.