[IgA antibodies in exogenous allergic alveolitis are more specific than IgG antibodies]

Nineteen sera from patients suffering from extrinsic allergic alveolitis (bird fancier's lung, farmer's lung) and 19 sera from asymptomatic persons demonstrating IgG-antibodies were examined for IgA-antibodies against pigeon serum, Micropolyspora faeni and Aspergillus fumigatus. The IgA-antibodies against pigeon serum and Micropolyspora faeni were less of ten false-positive than the corresponding IgG-antibodies. Hence the IgA-antibodies were more specific than the IgG-antibodies. However, the sensitivity of the IgA-antibodies was lower than that of the IgG-antibodies. On the other hand IgA-antibodies against Aspergillus fumigatus were scarcely more specific than the corresponding IgG-antibodies against pigeon and M. faeni. It would thus seem that IgA-antibodies can supplement the IgG-serodiagnosis of extrinsic allergic alveolitis.