The significance of immune disorder in tropical spastic paraparesis

Abstract

The reports of the occurrence of HTLV-1 infection and/or HTLV-1 associated myelopathy (HAM/tropical spastic paraparesis (TSP) in patients with certain organ-specific and nonorgan-specific autoimmune diseases prompted us to assess the relationship between TSP and humoral autoimmunity. Blood samples from 76 TSP patients, 60 asymptomatic HTLV-1 carriers and 100 HTLV-1 seronegative blood donors were examined for the presence of organ-specific and nonorgan-specific autoantibodies, reactive serological tests for syphilis, immunoglobulin and complement concentrations as well as immunecomplexes. High prevalences of autoantibodies (39/76, 51%), reactive serological tests for syphilis (23/76; 30%), hypergammaglobulinaemia (69/76, 90%) and complement fixing immune complexes (44/76, 58%) were found in the TSP patients. These indicators of immunological disorder were found in statistically significantly lower prevalences in asymptomatic HTLV-1 carriers (12/60, 20%; $\mathit{p}\mathrm{<}0.001$ ; 6/60, 10%; $\mathit{p}\mathrm{<}0.05$ ; 32/60, 53%; $\mathit{p}\mathrm{<}0.001$ and 8/60, 13%; $\mathit{p}\mathrm{<}0.001$ , respectively) and HTLV-1 seronegative blood donors (8/100, 8%; $\mathit{p}\mathrm{<}0.001$ ; 3/100, 3%; $\mathit{p}\mathrm{<}0.001$ ; 15/100, 15%; $\mathit{p}\mathrm{<}0.001$ and 5/100, 5%; $\mathit{p}\mathrm{<}0.001$ , respectively). The profiles of autoimmune phenomena observed in the patient and control groups revealed that they were associated with TSP rather than mere HTLV-1 infection and consequently pathogenetic significance. The array of immunological features present in TSP was suggestive of autoimmune disease resulting from immune dysfunction. Studies which explore the possible existence of HTLV-1 induced autoantibodies with specificity for antigens of the spinal cord in TSP might be useful in elucidating its pathogenesis.