CD4 and tropical spastic paraparesis: As shown in Figure 1C, the amount of HTLV-1 proviral DNA (which is the percent of HTLV-1-infected cells in PBMCs, provided the provirus integrates at the rate of 1 copy per cell) and the percentage of CD4+CD25+CCR4+ T cells were comparable in the HAM/TSP patients with low to medium HTLV-1 viral loads (HAM 1, HAM 5, HAM 6, HAM 4, HAM 7, and HAM 2).