PROTEIN-CONTENT IN BRONCHOALVEOLAR LAVAGE FLUID OF PATIENTS WITH ASTHMA AND CONTROL SUBJECTS

Background: Secretory component (SC), Clara cell protein (CC10) and to some extent, IgM are proteins locally synthetized in airways. Albumin , alpha 2-macroglobulin and alpha 1-antitrypsin are mainly plasma prot eins. In patients with asthma, blood proteins may occur in greater amo unts in bronchoalveolar lavage fluid (BALF) than in control subjects b ecause of plasma extravasation. These proteins were measured in BALF t o define markers of local synthesis and plasma exudation. Methods: Twe nty-four patients with asthma (mean age, 40 +/- 3.1 years) and 24 cont rol subjects (mean age, 29 +/- 11 years) were tested. Five aliquots of saline solution (50 mi) were instilled, and the recovered BALF was st ored. Clara cell protein was measured by a sensitive immunoassay techn ique based on the agglutination of latex particles. SC, immunoglobulin s, alpha 2-macroglobulin, alpha 1-antitrypsin, and albumin were measur ed by an immunoradiometric assay. Protein concentrations were normaliz ed to albumin. Results: In BALF from patients with asthma there was a significant increase in alpha 2-macroglobulin and IgM and a significan t decrease of SC, alpha 1-antitrypsin, and Clara cell protein compared with control subjects. Also, the ratio to albumin was significantly i ncreased for alpha 2-macroglobulin and IgM and decreased for SC. There was no correlation between the severity of asthma and the amount of p roteins, proteins. Conclusions: BALF protein content is significantly different in patients with asthma and cona ol subjects, for proteins p roduced locally and derived from plasma.