Increased activated human T cell lymphotropic virus type I (HTLV-I) tax11-19-specific memory and effector CD8(+) cells in patients with HTLV-I-associated myelopathy/tropical spastic paraparesis: Correlation with HTLV-I provirus load

To discern the T cell subtype associated with T cell differentiation, the e xpression of CD45RA and CD27 was measured from total CD8(high) cells and fr om human T cell lymphotropic virus type I (HTLV-I) Tax11-19 peptide-specifi c CD8(+) cells in peripheral blood lymphocytes of patients with HTLV-I-asso ciated myelopathy/tropical spastic paraparesis (HAM/TSP). Phenotypically de fined memory and/or effector cells (CD45RA(-)CD27(+), CD45RA(+)CD27(-), and CD45RA(-)CD272(-)) were increased in HAM/TSP CD8(+) cells, compared with t hose of HTLV-I-seronegative healthy control subjects. The percentage of hum an leukocyte antigen (HLA)-DR-positive cells was also increased in CD8(+) c ells of HAM/TSP, compared with those in HLA-DR(+)CD8(+) cells of healthy co ntrol subjects. HTLV-I provirus load correlated with the frequency of Tax11 -19-specific CD8(+) cells. The high frequency of memory and/or effector typ e HTLV-I Tax11-19-specific CD8(+) cells suggests that continuous restimulat ion driven by HTLV-I antigens in vivo may be associated with the pathogenes is of HAM/TSP.