The chain of events leading to HTLV-1 associated myelopathy/tropical spastic paraparesis (HAM/TSP)
would appear to be as follows: inefficient CTL response to HTLV-1, high proviral load and high level
of tax expression, high frequency of tax activated CD4+ T cells, frequent migration of CD4+ T cells to the central nervous system, release of IFN-γ, TNF and metalloproteinases by antigen-stimulated T cells, and tissue damage.