Increased frequency of HTLV-1 tetramer-specific CD8+CD127-/loCD25+ regulatory T-cells. A) Human PBMCs were gated on lymphocytes based on forward and side light scatter, and phycoerythrin-labelled HLA-A*2402 Tax301-309 or HLA-A*0201 Tax11-19 and HLA-A*24 CMV or HLA-A*02 CMV PP65 tetramer (Medical and Biological Laboratorie, Japan) specific CD8+ T-cells analyzed for intracellular FOXP3 and/or surface staining for CD25, CD8, GITR, and CD127 or appropriate isotype controls. The above representative data is shown after subtracting immunoglobulin isotype control background. B) Proportion of cells expressing the regulatory T-cell phenotype CD127-/lo CD25+ was higher for HTLV-1 Tax-specific CD8+ T-cells compared to CMV-specific T-cells (p<0.05) among asymptomatic carriers. Horizontal black bars represent means for the respective tetramer specific cell groups.