T-lymphocytosis and increased levels of soluble IL-2 receptors in bronchoalveolar lavage fluid in cases of HTLV-I-associated myelopathy with pulmonary involvement

Abstract

HTLV-I-associated myelopathy (HAM) is endemic in southwest Japan and frequently shows T-lymphocyte alveolitis. In the present study, we investigated 13 patients with HAM to determine if they showed increased levels of soluble IL-2 receptors, a marker of lymphocyte activation, in bronchoalveolar lavage (BAL) fluid. BAL studies showed that there was an increased proportion of lymphocytes in BAL fluid from HAM patients. The increased BAL lymphocytes consisted mainly of CD3+ cells and CD4+/CD8+ ratios were similar to those of normal controls. Serum levels of soluble IL-2 receptors were significantly elevated in patients with HAM as compared to normal controls (685 +/- 210 vs 286 +/- 49 U/ml, p less than 0.01). BAL levels of soluble IL-2 receptors were detectable in patients with HAM and these levels were approximately 13 times higher on average than those in serum (166 +/- 103 vs 18 +/- 13 U/mg albumin, p = 0.001). BAL Il-2R levels in patients with HAM correlated well with the number of T-lymphocytes and CD4+ cells in BAL fluid. These results suggest that T-lymphocytes infiltrating the lungs of HAM patients are activated locally to produce IL-2 receptors. In conclusion, immunological mechanisms seem to be responsible for the development of pulmonary lesions in patients with HAM.