[Human T-cell leukemia virus type I and adult T-cell leukemia-lymphoma]

Adult T-cell leukemia-lymphoma (ATL) is a unique T-cell leukemia-lymphoma that is closely associated with human T-cell leukemia virus type I (HTLV-I). HTLV-I is also associated with a benign disease, HTLV-I associated myelopathy. Main routes of the infection is through breast milk feeding from carrier mother to her baby, from carrier husband to wife, and by blood transfusion of carrier blood to recipient patients. The presence of anti-HTLV-I antibody is a definite sign of the carrier of HTLV-I, then screening of the antibody has been introduced with success to prevent the HTLV-I infection. Mechanism of leukemogenesis by the virus is not known. It is important to note that age-dependent occurrence of HTLV-I associated ATL can be simply described by a Weibull model. This suggests that ATL leukemogenesis might be the result of accumulation of numerous critical events, most likely somatic mutations, which are estimated to be five from the analysis. Although HTLV-I infection plays a primary role in the pathogenesis of ATL as an initiator, it may be only a prerequisite for accumulation of later events. The presence of HTLV-I negative ATL suggests that factor(s) other than HTLV-I infection may be involved in the leukemogenic process of ATL.