Figure 2.

HTLV-1 associated myelopathy/tropical spastic paraparesis and multiple sclerosis: Two chronic CNS inflammatory diseases, two viruses, a common immunopathologic mechanism? The text of this figure summarizes the tropism, biology and pathogenic potential of HTLV-1 and EBV and their association with HAM/TSP and MS, respectively. The HTLV-1-mediated immunopathological model of HAM/TSP is presented vis-a-vis the hypothesized EBV-mediated immunopathological model of MS. The left side of the sketch depicts the migration of HTLV-1-infected CD4 T cells and the activation of a cytotoxic response towards HTLV-1-infected CD4 T cells in the spinal cord in HAM/TSP, leading to production of the pro-inflammatory cytokine IFNγ and the lytic enzymes granzyme B and perforin, which play a key role in bystander tissue injury. On the right side of the sketch, a similar virus-driven immunopathological mechanism involving EBV-infected B cells and EBV-specific CD8 T cells is proposed for MS.