Antibody measurement in extrinsic allergic alveolitis.

Serum IgG antibody against purified avian antigens was quantified by radioimmunoassay in 507 active pigeon fanciers, of whom 110 had documented Pigeon Breeders Disease (PBD). The incidence of PBD increased from 3.7% in the antibody-negative group to 78% of those with IgG antibody greater than 30 micrograms/ml. The highest levels of antibody tended to occur in subjects with relatively short avian exposure, and a significant correlation between decreasing antibody levels and increasing years of avian contact was demonstrated, which was unrelated to age or smoking history. The antibody -positive subjects had lower daily hours of avian contact and this group which contained most of the PBD subjects demonstrated some self-regulation of antigen exposure.