Cellular immune responses to HTLV-I: immunopathogenic role in HTLV-I-associated neurologic disease

This review examines current information on cellular immune responses to the human T lymphotropic virus type I (HTLV-I). HTLV-I has been associated with a number of diseases, but this review focuses primarily on the relationship of HTLV-I with a slowly progressive neurologic disorder termed HTLV-I-associated myelopathy/tropical spastic paraparesis (HAM/TSP). In particular, this review discusses the role of cellular immune responses to HTLV-I in patients with HAM/TSP and how these responses may be associated with the pathogenesis of this disorder. While a number of immunologic responses have been shown to be abnormal in HAM/TSP patients, studies on HTLV-I-specific cytotoxic T-cell responses (cytotoxic T lymphocytes) are specifically examined. By defining such antigen-specific functional cellular host responses to HTLV-I, we hope to understand better the underlying mechanisms that may be involved in the neuropathology of HTLV-I-associated neurologic disease. This has led to a number of HTLV-I-associated immuno-pathogenic models that may be operative in HAM/TSP patients. Importantly, based on these models, potential immunotherapeutic strategies for disease intervention can be devised. Moreover, such an analysis may have significant implications for our understanding of other HTLV-I-associated clinical disorders.