The role of fibronectin in bronchoalveolar lavage fluid of asthmatic patients.

Allergic and chronic inflammation of the airway is regarded as the main pathogenesis of bronchial asthma, in which adhesion of inflammatory cells requires the expression of adhesion molecules. Thus, to clarify the role of fibronectin (FN) in the airway inflammation of bronchial asthma, FN levels in plasma and bronchoalveolar lavage fluid (BALF) from bronchial asthmatics were determined. FN concentrations in plasma and BALF were measured by enzyme-linked immunosorvent assay (ELISA) in 17 asthmatic patients and 10 healthy controls to elucidate the role of FN in allergic inflammation. The mean FN/albumin (Alb) level in the BALF of asthmatic patients was 2.973 micrograms/mg, which was significantly higher than that of healthy controls (0.727 microgram/mg). Non-atopic asthmatics showed a significantly higher level of FN in their BALF in comparison with atopic asthmatics, although the ratio of FN to albumin showed no significant difference. FN levels in BALF correlated significantly with total cell density (r = 0.71, P < 0.05) and alveolar macrophage density (r = 0.64, P < 0.05). FN levels in plasma did not correlate with those in BALF. In conclusion, increased FN in BALF, which was produced locally in the airways of asthmatic patients, is actively involved in the regulation of allergic inflammation.