Importance of anti-lung antibody in farmer's lung disease.

The presence of anti-lung antibody was evaluated in 20 patients with farmer's lung disease. Antibody was found in 14. In patients with disease of less than five years' duration, there was no evidence of any significant differences in vital capacity, total lung capacity, diffusion capacity, and PaO2 between those with and without anti-lung antibody. However, in patients with disease of longer than five years' duration, the diffusion capacity was lower in the anti-lung antibody-positive group (p less than 0.05). The prevalence of abnormalities of vital capacity and diffusion capacity and fibrosis on chest roentgenograms was higher in those who had anti-lung antibody and disease of more than five years' duration. The study suggests that anti-lung antibody is present before permanent measurable physiologic abnormality occurs and may potentiate the pulmonary damage during subsequent episodes.