Bronchopulmonary fluids in pulmonary alveolar proteinosis

Abstract

The alveoli of patients with pulmonary alveolar proteinosis (P.A.P.) become filled with a proteinaceous material, the origin of which is uncertain. The purpose of this study was to examine bronchopulmonary washings from four adults and one child with this disease who had total lung lavage for treatment of the hypoxemia caused by the disease process. In each instance a liter or more of lavage fluid was concentrated approximately four hundred fold by ultrafiltration for protein analysis. Quantitative determinations of the proteins in this fluid and in serum were performed in quadruplicate by the Lowry method, radial diffusion, or radioimmunoassay. There was a selective increase of IgG in washings from all five patients with P.A.P., and there was a lesser increase of IgA, suggesting either a local production or a mechanism for concentrating these immunoglobulins. Albumin usually comprised a similar proportion of the total protein in serum and washings, but alpha-2 macroglobulin comprised less than half that in serum in each instance, suggesting that equal transudation of large and small proteins did not occur. There was considerable variation in the relative proportion of IgM, IgD, and IgE in washings compared to serum, suggesting that each of these immunoglobulins is metabolized (synthesized, transported, or catabolized) by an independent mechanism in the lung. Secretory piece was demonstrated in the bronchial washings of each patient, including controls, as were two soluble nonserum proteins. Fibrinogen was identified in the washings of the three patients with P.A.P. Large amounts of insoluble surfactant-like material were also present in the washings of each of the patients with P.A.P.