Abstract
The cellular components of bronchoalveolar lavage (BAL) fluids from 26 patients with hypersensitivity pneumonitis were analyzed with regard to the period of antigen exposure before BAL procedure. In the early phase of antigen exposure BAL fluids contained increased neutrophils as well as lymphocytes while a low percentage of neutrophils and a prominent increase of lymphocytes were observed in chronic antigen exposure. Furthermore, the increased neutrophils decreased rapidly after cessation of antigen exposure while lymphocytes decreased gradually. In the BAL fluids of patients with summer-type hypersensitivity pneumonitis, CD4+ percentages and CD4/CD8 ratios were significantly decreased, but CD8+ percentages significantly increased during antigen exposure compared with that in healthy controls. However, the actual CD4+ cell counts in BAL fluids significantly increased while CD4+ percentage decreased. Thus, CD4+ as well as CD8+ may play important roles in the pathogenesis of hypersensitivity pneumonitis.
Soluble IL-2 receptor (sIL-2R) levels in BAL fluids and serum obtained from patients with hypersensitivity pneumonitis, especially serum sIL-2R during the active phase, were significantly higher than those of normal controls, indicating that the elevated sIL-2R level reflected a highly activated immune response. In relation to pulmonary function, the lymphocyte percentage showed a significant inverse correlation with %TLC and PaCO2, while neutrophil percentage showed significant correlation with %TLC and inverse correlation with FEV1.0%.
These results suggest that neutrophilia in BAL fluids affects bronchobronchiolar disorders during the early phase, and lymphocytosis in BAL fluids regulates organic changes of the lung in hypersensitivity pneumonitis.
