Crossed Immunoelectrophoretic Analysis of ARDS Lavage Proteins

Abstract

Serum proteins in normal and ARDS bronchoalveolar lavages were analyzed using crossed Immunoelectrophoresis. Normal lavages demonstrated relatively few proteins (albumin, α₁antitrypsin, transferrin, and haptoglobin) in low concentrations. In contrast, substantial amounts of all identifiable serum proteins were detected in ARDS lavages. IgA was apparently locally produced. Two of the largest proteins, β-lipoprotein (mol wt > 2 million) and IgM (mol wt ~ 900,000) were found to be complexed as evidenced by their coprecipitation in a single spike in ARDS lavage. Electrophoretic modifications of ARDS albumin and α₁antitrypsin precipitation peaks and partial identity spurring of the α₁-lipoprotein peak with other precipitation loops indicated possible complex formation between these proteins and other possibly pathogenic lung fluid constituents. Similarly, modifications of orosomucoid and Gc-globulin peaks indicated possible molecular alterations resulting from interactions with other components. The relatively few protein modifications exhibited in ARDS lavages together with α₁antitrypsin-protease complex formation confirm the relative absence of substantial proteolytic activity in ARDS edema fluids obtained within 12 hr of the onset of the syndrome demonstrated in previous studies.