Complement consuming antibodies against a modified human serum protein in pigeon breeders' disease.

The sera of patients with pigeon breeders' disease contain precipitating and human complement consuming antibodies against pigeon dropping antigens. Cessation of antigen exposure results in a decrease of precipitins below the level of detection in immunodiffusion. Complement consuming antibodies remain present, however, despite antigen avoidance. A close correlation is observed between human complement consumption tests with pigeon dropping antigens PDF1-A or pigeon cropmilk IgA and a modified human serum gamma-globulin. Isolation of this protein is readily achieved by its non-specific adsorption onto activated Sepharose 4B and subsequent elution with 1 M acetic acid. This modified protein may act as an autoantigen in pigeon breeders' disease, maintaining human complement consuming antibodies for years in subjects with no further bird antigen contact.