To evaluate cellular and protein components in the lower respiratory tract of patients with idiopathic pulmonary fibrosis (IPF) and chronic hypersensitivity pneumonitis (CHP), limited broncho alveolar lavage was done in 58 patients (19 IPF, 7 CHP, and 32 controls). Analysis of the cells and protein in the lavage fluids from patients with IPF revealed an inflammatory and eosinophilic response and a significant elevation of IgG in the lungs. With corticosteroid therapy, inflammation diminished but the eosinophils remained. Lavage fluid from patients with CHP also had eosinophils and elevated levels of IgG. However, in contrast to IPF, lavage fluid from CHP patients contained IgM, fewer inflammatory cells, and a strikingly increased number (38-74%) of lymphocytes. Identification of lavage lymphocytes in CHP showed that T lymphocytes were significantly elevated and B lymphocytes were decreased, compared to peripheral blood. These studies suggest that the lung in IPF and CHP may function as a relatively independent immune organ, and that analysis of cells and proteins in broncho-alveolar lavage fluid may be of diagnostic, therapeutic, and investigative value in evaluating patients with fibrotic lung disease.
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