Protein permeability in the adult respiratory distress syndrome. Loss of size selectivity of the alveolar epithelium

Abstract

12 times the levels in normals or cardiac edema patients. BALF/plasma total protein ratios and measurements of epithelial lining fluid protein also separated the patient groups. The large proteins IgM and α2-macroglobulin were found in ARDS BALF at >90 times the concentrations of normal or cardiac edema fluid. The relationship of distribution coefficient vs. log molecular weight for seven proteins (54,000-900,000 mol wt) hyperbolically increased in normals but was flat in ARDS patients. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed a paucity of high molecular weight proteins in normal and cardiac edema BALF, but demonstrated the full spectrum of plasma proteins in ARDS BALF. We conclude that normal size selectivity is preserved in cardiac edema but is destroyed by the alveolar-capillary injury of ARDS.