CD4 and tropical spastic paraparesis: Although CCR4 is known to be selectively expressed on Treg and Th2 cells in healthy individuals, more detailed flow cytometric analysis of Foxp3 expression in CD4+CD25+CCR4+ T cells of HAM/TSP patients demonstrated that the frequency of the Foxp3− population was greatly increased in CD4+CD25+CCR4+ T cells [54].