IFNG and tropical spastic paraparesis: Therefore, CD4+CD25+CCR4+ T cells from PBMCs of 3 HDs, 4 HAM/TSP patients, and 3 ATL patients were isolated by FACS sorting, and the mRNA expression levels of IFN-γ, IL-2, and IL-17 were quantified by real-time RT-PCR (Figure 4C).