SEQUENTIAL EVALUATION OF CLINICAL AND IMMUNOLOGICAL FINDINGS IN HYPERSENSITIVITY PNEUMONITIS - SERIAL SUBCLASS DISTRIBUTION OF ANTIBODIES

The long-term outcome of hypersensitivity pneumonitis (HP) is variable depending upon the individual. To evaluate the mechanisms involved in the progression or regression of HP, the longitudinal changes in pulm onary function test results, bronchoalveolar lavage (BAL) cells and th e subclass distribution of IgA and IgG antibodies were investigated in 14 patients with HP, including 5 cases with bird fancier's lung (BFL) . The present study has shown that: (I) All patients with bird fancier 's lung (BFL) demonstrated either a restrictive pattern or a reduced d iffusing capacity for carbon monoxide (DLco), or both; one BFL patient showed deterioration in %VC and %DLco after avoidance of direct expos ure. (2) Ail three patients with summer type HP who demonstrated reduc ed VC and DLco at the initial test improved, (3) T cells, especially C D8 cells, were predominant in the BAL fluids of the summer type HP pat ients, whereas either CD8 or CD4 cells were less common, but showed an increase in the BAL fluids of the BFL patients, depending upon indivi duals, (4) The number of CD8 cells in the summer type HP patients decr eased gradually, but at a slower rate than in the BFL patients; (5) An tibody activities of IgG1, G2, G3, G4, and Al subclasses in the sera a nd BAL fluids were detected during the 5-year observation period; (6) IgA2 subclass was abundant in the BAL fluids of both BFL and summer ty pe HP patients, in contrast to very minute amounts in sera; (7) The le vel of IgG2 antibody in the BAL fluids of the summer type HP patients was low (0.15 +/- 0.05) as compared to that in BFL (0.82 +/- 0.29); (8 ) The level of IgG3 antibody in the BAL fluids of summer type BP patie nts was lower (0.18 +/- 0.05) than in BFL (1.01 +/- 0.1); and (9) The antibody activities in most immunoglobulin subclasses fluctuated, but declined gradually in the BAL fluids, although they were well beyond t he normal ranges. We were unable to predict the progression or the dis appearance of hypersensitivity pneumonitis based merely upon the resul ts of the present study. (C) 1994 Academic Press, Inc.