CD4 and leprosy: Before de Castro et al. (2020) [11] studied the role of Tregs on T2LR, Negera et al. (2017) [13] conducted a comprehensive investigation of the Treg cells in individuals diagnosed with erythema nodosum leprosum. A cohort research of 46 individuals exhibiting erythema nodosum leprosum reaction and 31 individuals with non-reactional lepromatous leprosy were selected. There is a correlation between the presence of T2LR and a reduction in the proportion of Treg cells, as well as an increase in the CD4+ to CD8+ T cell ratio.