Local and systemic antibody production in horses affected with chronic obstructive pulmonary disease.

An enzyme-linked immunosorbent assay (ELISA) was used to quantify isotype-specific antibody to Micropolyspora faeni and to Aspergillus fumigatus in the sera and bronchoalveolar lavage fluid (BALF) of normal horses, horses with chronic obstructive pulmonary disease (COPD) and horses with other chronic respiratory diseases. Elevated antibody levels were not detected in the sera of affected horses. However, both IgE and IgA antibody to both allergens was significantly elevated in BALF in COPD affected horses sampled both when symptomatic and asymptomatic. Elevated levels were also found in animals that developed a chronic cough after an acute onset with symptoms compatible with a respiratory virus infection. In one animal a ten fold increase in IgE antibody to the two allergens developed after an interval of 7 weeks. These findings are supportive of a central role of local IgE antibody to mould allergens in the immunopathogenesis of COPD, and also suggest that respiratory viral infection may predispose to the development of COPD in some horses.