Background and objective: The long-term outcome of bird fancier's lung appears to be variable. The objective of this study is to clarify the sequelae of disease process in bird fancier's lung, with special reference to the humoral and cellular immune responses after avoidance of direct antigen exposure.
Methods: Five patients with bird fancier's lung were studied for various parameters including pulmonary function tests, cellular profiles of bronchoalveolar lavage (BAL) fluids, determinations of antibodies in BAL fluids and sera, and antigen-induced proliferation of peripheral and bronchoalveolar lymphocytes during the 5 years of follow-up.
Results: Four of five patients showed improvement in pulmonary function, and one showed marked deterioration. This patient's room was close to the pigeon coop where her son was breeding pigeons, resulting in low-grade antigenic stimulation. Three patients demonstrated an increase in CD8+ cells in BAL fluid, but the remaining two showed an increase in CD4+ cells. The levels of IgA antibodies remained unchanged, whereas IgG levels started declining after the first 3 years of follow-up. Antigen-induced proliferation of BAL lymphocytes from all five patients and blood lymphocytes from four of five patients became weaker and gradually approached normal levels. One patient had pulmonary fibrosis and showed significant reduction in pulmonary functions but elevated reactivity of BAL lymphocytes to pigeon antigens.
Conclusion: This follow-up study demonstrates persistence of sensitized lymphocytes and antibody production in the respiratory tract and warrants careful evaluation of patients with bird fancier's lung, even after antigen avoidance.