Quantitation of cellular and extracellular constituents of the pulmonary lining in rats by using bronchoalveolar lavage. Effects of silica-induced pulmonary inflammation.

The efficacy of bronchoalveolar lavage in the removal of cellular and extracellular components of the lining layer from the lungs of silica-treated and control rats was determined. Exponential functions were fitted to curves generated by plotting the quantity of lining layer constituent removed from the lungs by bronchoalveolar lavage versus the lavage number. From these exponential functions we determined the total amount of constituent available in the pulmonary extracellular lining and hence the efficacy of the lavage procedure in removing materials from the lungs. With control rats the removal of extracellular phospholipids, soluble protein, alkaline phosphatase, and beta-N-acetylglucosaminidase by bronchoalveolar lavage occurred at significantly different rates. Removal of 95% of the total available extracellular phospholipid, beta-N-acetylglucosaminidase, soluble protein, and alkaline phosphatase from the lungs required 4, 4, 8, and 11 lavages, respectively. Removal of 95% of the total available alveolar macrophages required 18 lavages. The influence of pulmonary inflammation on the efficacy of the lavage procedure was investigated by injecting silica dust intratracheally into the lungs of rats (50 mg/200- to 250-g rat) and after 3 days performing the analyses. Silica caused an inflammatory condition in the lungs resulting in the accumulation of materials in the alveoli. Highly significant increases in soluble protein (16-fold), alkaline phosphatase (9-fold), and beta-N-acetylglucosaminidase (11-fold), polymorphonuclear leukocytes, eosinophils, and lymphocytes were observed. Alveolar macrophages and extracellular phospholipid were not significantly elevated at 3 days after dosing. Silica did not alter the efficacy of the lavage procedure in removing from the lungs any of the extracellular constituents of the lung lining.(ABSTRACT TRUNCATED AT 250 WORDS)