Experimental silicosis: morphologic and biochemical abnormalities produced by intratracheal instillation of quartz into guinea pig lungs

Six months after intratracheal instillation of silica, histologic, ultrastructural, cytologic, and biochemical studies were performed on the lungs of guinea pigs. The tissue response consisted of both diffuse alveolar septal infiltration with interstitial fibrosis and granulomatous infiltration with nodular fibrosis. Ultrastructural studies confirmed the presence of a mixed inflammatory exudate in the alveolar interstitium (histiocytes, neutrophils, eosinophils, and lymphocytes) and the Type II lining of cell hyperplasia. The number of lung cells recovered by lavage and the proportions of neutrophils and multinucleated cells in bronchoalveolar cells were significantly greater in experimental animals (P < .05) than in controls (intratracheal saline). Total lung collagen and collagen synthesis by cultured lung tissue were also increased in the experimental animals. Since the response of guinea pig lung to intratracheal silica included pathologic features common to human silicosis and idiopathic pulmonary fibrosis, this model has the potential for improving our understanding of both of these important clinical disorders.