Evaluation of some immunological parameters in interstitial lung disease by discriminant analysis.

In 37 subjects affected by interstitial lung diseases (19 patients with pulmonary sarcoidosis, 11 with hypersensitivity pneumonitis, 7 with idiopathic pulmonary fibrosis), we have compared by discriminant analysis (Statistical Package for the Social Sciences, version 8.3) 17 biological parameters derived from bronchoalveolar lavage analysis, gallium-67 scanning and lung biopsy. The aim of the study was to analyze the parameters of these three groups by forming one or more linear combinations of the discriminant variables. In particular, we tried to define the ability of such parameters to define these interstitial lung diseases and the relative importance of the data examined. The functions obtained are highly discriminant, so that the three groups are well distinguished among themselves; it means that the variables employed discriminate among the diseases studied. Among the variables considered, differential cell count, immune complex determination, gallium-67 lung scanning have the most important discriminant capacity. Discriminant analysis emphasizes that the three diseases are mediated by different immune mechanisms and underlines the role of each mechanism in determining the disease.