The importance of the phenotypic markers used to define Tregs, discussed at the beginning of this review, is highlighted in the work carried out by Zewdie et al. (58), who found that while CD4+CD25+/hi T-cell frequencies were higher in patients with active TB than individuals with LTBI, there were no differences in the frequency of CD4+CD25+CD127lo, CD4+CD25+FoxP3+, or CD4+CD25+FoxP3+CD127lo T cells. The gene discussed is CD4; the disease is tuberculosis.