Human T-Cell Leukemia Viruses: Human Disease

Abstract

In 1980, human T-cell leukemia/lymphoma virus type 1 (HTLV-1) was the first oncogenic human retrovirus to be discovered. Fifteen to twenty millions individuals are infected worldwide. HTLV-1 is transmitted from mother to child, by sexual contacts, and through blood transfusion. It is the etiological agent of two diseases of very bad prognosis: a malignant T-cell lymphoproliferation named adult T-cell leukemia/lymphoma (ATLL) and a chronic neuromyelopathy named tropical spastic paraparesis/HTLV-1 associated myelopathy (HAM/TSP). At onset, the main clinical ATLL symptoms are: lymphadenopathy, hepatomegaly, splenomegaly, specific skin lesions, and hypercalcemia, with a proliferation of CD4+, CD25+ cells, and an elevated white blood count. There is a large diversity in the clinical presentation and evolution of the disease. The survival rate of ATLL patients, especially in the acute leukemic or lymphomas forms, is very poor. TSP/HAM is defined as a chronic spastic paraparesis with signs of bilateral pyramidal tract lesions and minor sensory signs. The onset is insidious with gait disturbance and the evolution is slowly progressive with no remission. High levels of anti-HTLV-1 antibodies are present in the serum and the cerebrospinal fluid. HTLV-1 infection has also been associated with other clinical conditions including uveitis, infective dermatitis, and myositis.