In order to identify the Treg cells in human leprosy, immunophenotyping was done for the markers CD4, CD25 and FoxP3 (Fig 1A) on PBMCs derived from leprosy patients (BT/TT vs. BL/LL) (n = 15 in each group) and healthy contacts (HCs, n = 10). Here, FOXP3 is linked to leprosy.