Immunological studies in tropical spastic paraparesis.

Tropical spastic paraparesis (TSP) and other chronic-progressive myelopathies have been clearly associated with increased serum and cerebrospinal fluid antibody titers to human T-lymphotropic virus type I (HTLV-I). However, little is known about the cellular immune function in TSP. In the present study, activated T lymphocytes were found in the peripheral blood of patients with TSP. Specifically, there were increased numbers of large CD3+ cells that also expressed HLA-DR and interleukin-2-receptor molecules. A significantly elevated spontaneous lymphoproliferative response was demonstrated in all patients tested. Generation of measles virus-specific cytotoxic T-cell response was reduced in 4 of 4 patients. This was similar to previous findings in patients with multiple sclerosis. However, unlike multiple sclerosis, reduced generation of cytotoxic T-cell response to influenza and mumps viruses was observed in 2 of 4 patients. These observations confirm further the strong association between TSP and an HTLV-I-like virus and suggest that the observed abnormalities of the cellular immune response in TSP are related to infection of lymphocytes by the retrovirus.