title: Tumor immunity against adult T-cell leukemia.
abstract: Human T-cell leukemia virus type-I (HTLV-I) causes adult T-cell leukemia (ATL) in a small population of infected individuals after a long incubation period. Although the process of clonal evolution of ATL cells may involve multiple steps, ATL cells from half of the ATL cases still retain the ability to express HTLV-I Tax, a key molecule of HTLV-I leukemogenesis. A recent finding of reactivation of Tax-specific cytotoxic T lymphocytes (CTL) in ATL patients after hematopoietic stem cell transplantation suggests the presence of Tax expression in vivo and potential contribution of the CTL to antitumor immunity. This is consistent with the results of a series of animal experiments indicating that Tax-specific CTL limit the growth of HTLV-I-infected cells in vivo, although the animal model mimics only an early phase of HTLV-I infection and leukemogenesis. Establishment of an insufficient HTLV-I-specific T-cell response and an increased viral load in orally HTLV-I-infected rats suggests that host HTLV-I-specific T-cell response at a primary HTLV-I infection can be a critical determinant of persistent HTLV-I levels thereafter. These findings indicate that Tax-targeted vaccines may be effective for prophylaxis of ATL in a high-risk group, and also for therapy of ATL in at least half the cases.
authors.affiliation: Department of Immunotherapeutics, Tokyo Medical and Dental University, Medical Research Division, Bunkyo-ku, Tokyo 113-8519, Japan. kann.impt@tmd.ac.jp
authors.forename: Mari
authors.initials: M
authors.lastname: Kannagi
authors.forename: Nanae
authors.initials: N
authors.lastname: Harashima
authors.forename: Kiyoshi
authors.initials: K
authors.lastname: Kurihara
authors.forename: Takashi
authors.initials: T
authors.lastname: Ohashi
authors.forename: Atae
authors.initials: A
authors.lastname: Utsunomiya
authors.forename: Ryuji
authors.initials: R
authors.lastname: Tanosaki
authors.forename: Masato
authors.initials: M
authors.lastname: Masuda
authors.forename: Masao
authors.initials: M
authors.lastname: Tomonaga
authors.forename: Jun
authors.initials: J
authors.lastname: Okamura
mesh_terms: D000818:Animals; D000956:Antigens, Viral / Q000276:immunology; D018450:Disease Progression; D018380:Hematopoietic Stem Cell Transplantation; D015368:Human T-lymphotropic virus 1 / Q000235:genetics / Q000276:immunology* / Q000502:physiology; D006801:Humans; D015459:Leukemia-Lymphoma, Adult T-Cell / Q000276:immunology* / Q000517:prevention & control / Q000628:therapy / Q000821:virology
chemical_list: D000956:Antigens, Viral