The mast cell and signs of pulmonary fibroblast activation in sarcoidosis.

Hyaluronate and type III procollagen propeptide were assayed in bronchoalveolar lavage (BAL) fluids from patients with sarcoidosis. Levels were significantly elevated suggesting increased rates of synthesis of these connective tissue components in the lung. They were strongly related to each other (p less than 0.001) favoring the idea of a common cellular origin, as a suggestion activated fibroblasts. There was a significant inverse correlation (p less than 0.001) between lavage hyaluronate or procollagen propeptide and the clinical severity of the disease process defined by lung volume, diffusion capacity and pulmonary radiological findings. Correlation of clinical findings with lavage cell profiles was poor except for recovered mast cells (p less than 0.001). Lavage mast cell counts were also closely associated with BAL fluid hyaluronate and procollagen peptide (p less than 0.001). These findings may reflect a link between the mast cell, the activation of fibroblasts, and the progress of connective tissue changes in sarcoid lung.