Persistent mucin glycoprotein alterations in equine recurrent airway obstruction

Horses with the episodic asthmalike condition of recurrent airway obstructi on (RAO) have bouts of inflammation and bronchoconstriction. associated wit h indoor housing. To assess the potential differences in airway secretions between RAO-affected and control horses, methods to quantify mucus secretio ns were developed and applied to bronchoalveolar lavage fluid. The relative difference in the amount of mucin glycoproteins between control and RAO-af fected horses was assessed with a carbohydrate side chain-specific monoclon al antibody (4E4) in an enzyme-linked immunosorbent assay and by carbohydra te-specific enzyme-linked lectin assays. Significantly increased levels of 4E4-immunoreactive glycoprotein and the mucin-associated carbohydrates fuco se (alpha -1,2 linkage) and N-acetylglucosamine were detected in RAO-affect ed horses in acute disease. RAO-affected horses in remission maintained sig nificantly elevated levels of alpha -1,2-fucose and N-acetylglucosamine, wh ereas the 4E4-immunoreactive glycoprotein levels displayed a trend toward a n increase over control levels. These results indicated that persistent cha nges in the quantity and/or quality of mucus glycoproteins occurred in the RAO-affected horses.