HTLV-I UVEITIS

Human T-cell lymphotropic virus type I (HTLV-I) is known to cause adul t T-cell leukemia/T-cell lymphoma and tropical spastic paraparesis/HTL V-I-associated myelopathy. Recent seroepidemiologic, clinical, and vir ologic studies indicate that the virus is also related to a certain ty pe of uveitis, which has been classified as uveitis without defined et iologies or idiopathic uveitis. According to the seroepidemiologic sur vey, the seroprevalence of HTLV-I in patients with idiopathic uveitis was significantly higher than that of two control groups, that is, pat ients with uveitis with defined etiologies and patients with nonuveiti c ocular diseases, Clinically, the uveitis seen in HTLV-I carriers is characterized by moderate to severe cellular infiltration in the eye a nd by moderate retinal vasculitis, and the intraocular inflammation re sponds well to corticosteroid therapy. Interestingly, 25% of female pa tients with the disease had a previous history of Graves disease with hyperthyroidisms. The following virologic, molecular biologic findings suggest that cytokines produced by HTLV-I-infected T cells in the eye play the central role in the pathogenic mechanisms of the uveitis: (a ) the virus load in the peripheral blood monocytes analyzed by the qua ntitative polymerase chain reaction methods was significantly greater in patients with the uveitis than in asymptomatic carriers, (b) the pr oviral DNA of HTLV-I and the gene expression of the virus at the mRNA level was detected in the infiltrating cells from the eyes of the pati ents, (c) the virus particles were detected by electron-microscopic ex amination in the T-cell clones established from the intraocular fluid of the patients, and (d) the HTLV-I-infected T cells produced a variet y of cytokines without any stimuli, such as interleukin (IL)-1 alpha, IL-2, IL-3, IL-6, IL-8, IL-10, tumor necrosis factor alpha, interferon -gamma, and granulocyte-macrophage colony-stimulating factor, Based on the seroepidemiologic, clinical, and virologic data, the uveitis seen in HTLV-I carriers is considered to be a distinct clinical entity rel ated to HTLV-I infection, and the disease is designated as HTLV-I uvei tis.