Pathogenesis
When infected by HTLV-1 the host mounts an antigen-specific immune response toward the HTLV-1 antigen. Cytotoxic T-lymphocytes of the host’s immune response release cytokines in an effort to fight the infection. These cytokines facilitate the transendothelial migration of lymphocytes across the blood–brain barrier. Once cytokines are within the central nervous system, demyelination is brought as a result of bystander cell injury. The disease is chronic, progressing slowly, usually causing symptoms 20–30 years after infection.
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