CD4 + FoxP3+ T-cell frequency in both HTLV-1-infected and healthy donors. Data are presented as median (interquartile range). The Mann–Whitney U-test was used to compare healthy donors (HD; n = 5) and asymptomatic HTLV-1-infected individuals (ASS n = 15). ASS individuals had PVL < 1% infected cells, except one 26% of infected cells. *p = 0.02.