NEUROAXONAL DYSTROPHY IN HTLV-1-ASSOCIATED MYELOPATHY TROPICAL SPASTIC PARAPARESIS - NEUROPATHOLOGIC AND NEUROIMMUNOLOGIC CORRELATIONS

Detailed neuropathologic and immunohistologic analysis of a case of se rologically and polymerase chain reaction-confirmed human immunodefici ency virus type I (HTLV-I)-associated myelopathy/tropical spastic para paresis (HAM/TSP) is reported in a 73-year-old North American black wo man. In addition to the usual neuropathologic features of HAM/TSP, inc luding tractal degeneration of the spinal cord, leptomeningeal and per ivascular fibrosis, perivascular demyelination and chronic inflammatio n, neuroaxonal spheroids were prominent in the spinal cord. Neuroaxona l dystrophy was characterized by neurofilamentous masses that were imm unoreactive for phosphorylated neurofilament epitopes, but not ubiquit in. Neuroimmunologic analysis of the inflammatory reaction revealed a prevalence of CD8+ T cells and class I major histocompatibility molecu les (MHC) (HLA-ABC and beta2-microglobulin), but very few CD4+ T cells . Microglia were highly reactive for class II MHC (HLA-DRalpha) and th is was attributed to activation, rather than CD4 interaction, since CD 4 presence was minimal. Inflammatory cytokine immunoreactivity was als o detected in glia. It is concluded that the cumulative effects of cyt otoxic T cell (CD8) infiltration and the possible involvement of cytok ines were responsible for the unusual degree of neuroaxonal dystrophy and vascular fibrosis, as well as the observed demyelination in this c ase.