Expression of human T lymphotropic virus type 1 (HTLV-1) tax/rex gene in fresh bronchoalveolar lavage cells of HTLV-1-infected individuals

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Abstract
Accumulating evidence has suggested the involvement of HTLV‐1 in the inflammatory lesions of various organs, including the lung. However, the causal relationship between HTLV‐1 and inflammatory responses in the organs remains to be elucidated. In order to evaluate the expression of HTLV‐1 and its effects in the lung, we examined the expression of mRNA for the HTLV‐1 tax/rex gene in fresh bronchoalveolar lavage cells (BALC) and peripheral blood mononuclear cells (PBMC) of 23 seropositive individuals, including six patients with HTLV‐1‐associated myelopathy/tropical spastic paraparesis (HAM/TSP), by use of an improved method of reverse transcription‐polymerase chain reaction (RT‐PCR). The tax/rex mRNA was more frequently detected in BALC than in PBMC. All the HAM/TSP patients and eight of 17 carriers without neurological symptoms showed the expression of tax/rex mRNA in the BALC. IgM class antibodies to HTLV‐1 were preferentially detected in sera of the tax/rex mRNA‐positive individuals. The detection of tax/rex mRNA correlated closely with the presence of lymphocytosis accompanied by an elevated proportion of IL‐2 receptor‐bearing T cells in the BALC. Our findings indicate the crucial role of viral expression in the inflammatory response in the lung in HTLV‐1‐infected individuals.