CD4 and adult T-cell leukemia/lymphoma: Although approximately 90% of the infected individuals remain asymptomatic carriers during their lives, chronic infection with HTLV-1 can result in multiple severe pathologies; these include the adult T-cell leukemia/lymphoma (ATLL), an aggressive neoplasm of CD25+ CD4 T-cells in about 5% of infected individuals after a prolonged latent period of 30–50 years (2, 6).