[Lymphocyte subsets in bronchoalveolar lavage fluid from patients with idiopathic interstitial pneumonia]

Lymphocyte activation may be involved in interstitial inflammatory processes in the lungs. We analyzed lymphocytes in bronchoalveolar lavage fluid obtained from 15 patients with idiopathic interstitial pneumonia (IIP) and from 7 controls. Clinical criterial were used to divide the patients with IIP into two groups: acute (n = 5) and chronic (n = 10). Lymphocytes in the bronchoalveolar lavage fluid were analyzed with a flow-cytometric two-color system. Differential cell counts showed that percentages and numbers of lymphocytes were significantly higher in patients with acute IIP (44.2 +/- 25.2%, 12.3 +/- 8.18 x 10(4)/ml) than in controls (8.31 +/- 3.66%, 0.69 +/- 0.39 x 10(4)/ml, p < 0.05) and in patients with chronic IIP (8.44 +/- 6.11%, 1.58 +/- 1.08 x 10(4)/ml, p < 0.05). In particular, percentages and numbers of CD8+ S6F1+ lymphocytes, which are regarded as activated cytotoxic T lymphocytes were markedly higher in patients with acute IIP (32.3 +/- 16.0%, 39.6 +/- 37.1 x 10(3)/ml), than in controls (6.31 +/- 1.69%, 0.42 +/- 0.25 x 10(3)/ml, p < 0.05) and in patients with chronic IIP (10.6 +/- 6.16%, 1.88 +/- 1.42 x 10(3)/ml, p < 0.05). These data suggest that patients with acute IIP differ from those with chronic IIP in the percentage and the number of lymphocytes in bronchoalveolar lavage fluid, and that activated cytotoxic T lymphocytes may play an important role in the pathogenesis of acute IIP.