Circulating autoantibodies in patients with pigeon breeder's disease

Sera from 19 patients with hypersensitivity pneumonitis induced by avian antigens were studied in order to determine the presence of circulating autoantibodies. IgM and IgG rheumatoid factors were positive in 68% and 100% of the cases respectively. IgM-rheumatoid factor was detected with at least two methods, showing titers between 1:20 and 1:1280 by the latex agglutination test and between 140 and 579 IU/ml by nephelometry test. The IgG rheumatoid factor was studied by the indirect immunofluorescence technique, showing positive determinations in all of our hypersensitivity pneumonitis patients. Titers of these autoantibodies ranged from 1:80 to 1:640. In addition, we studied the presence of antinuclear, anti-nDNA, anti-mitochondrial, and anti-smooth muscle antibodies by the immunofluorescence test using HEp-2 cells, mouse kidney, and Crithidia luciliae targets. Sera from all of our hypersensitivity pneumonitis patients have negative results of autoantibodies to these antigens. Negative results of autoantibodies to the nRNP, Sm, SS-A(Ro) and SS-B(La) nuclear antigens by counterimmuno-electrophoresis and double immunodiffusion techniques were also obtained. As controls we studied 14 healthy individuals and 8 subjects exposed to avian antigens but without hypersensitivity pneumonitis symptoms and no positive determinations for rheumatoid factor, antinuclear antibodies, as well as to anti-mitochondrial and anti-smooth muscle antibodies, were found. These findings support that different immune abnormalities are present in patients with hypersensitivity pneumonitis induced by avian antigens. One of these immune alterations or a combination of them may promote or facilitate the acute interstitial lung injury and/or perpetuate a chronic inflammatory process.