Influence of human T lymphotrophic virus type I on diffuse pan-bronchiolitis

Human T lymphotrophic virus type-I (HTLV-I), a human retrovirus, infects CD4(+) lymphocytes and is thought to modify their function and a possible association with pulmonary diseases has also been suggested. However, little is known about the influence of HTLV-I on diffuse pan-bronchiolitis (DPB), a chronic inflammatory lung disease with infiltration of lymphocytes and hyperplasia of the bronchus-associated lymphoid tissue. In this study, 35 DPB patients with and without HTLV-I infection were examined. HTLV-I positive DPB patients were likely to have a larger affected area with lower FEV(1). The CD3(+)/CD25(+) lymphocyte percentage was significantly higher in the BALF of HTLV-I positive patients than in negative patients. MIP-1 alpha, IP-10 and levels in BALF were also significantly higher in HTLV-I positive patients than in negative patients. The levels of MCP-1 and IL-8 were not significantly different. In HTLV-I positive patients, the MIP-1 alpha and IP-10 levels showed a significant positive correlation with the percentage of CD3(+)/CD25 lymphocytes. BALF cells of all HTLV-I positive DPB patients showed expression of p40(tax) mRNA. We suggest that HTLV-I infection may modify DPB pathogenesis via activation of T cells. We also found that the frequency of ATL development in HTLV-I positive DPB patients was significantly higher than in all HTLV-I positive patients (OR = 8.22, 95% CI = 2.61-25.9, P < 0.01). The levels of TGF-beta in patients who developed ATL were significantly lower than in patients who did not develop ATL. Sensitivity and specificity were 80% and 85.7%, respectively (cut-off = 20 pg/ml). We also propose that these features should be taken into consideration in the treatment of DPB in HTLV-I infected individuals.