Furthermore, to examine whether these functional alterations in the CD4+CD25+CCR4+ T cells from HAM/TSP patients are specific to the cell subtype, we investigated the intracellular cytokine expression of IFN-γ, IL-17, and IL-10 in each of the 4 cell subtypes from 8 HDs and 7 HAM/TSP patients by FACS after PMA and ionomycin stimulation (Figure 5B). Here, CCR4 is linked to tropical spastic paraparesis.