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

Abstract

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.