Since Treg cells produce regulatory cytokine IL-10 that modulates the entire repertoire (Th1/Th2/Th17) of CD4+ effector cell responses indiscriminately in filariasis that limits the Th1 response [22,23],we have evaluated the level of IL-10 in two groups of children to draw the functional relationship with Tregs. The gene discussed is CD4; the disease is filariasis.