Regulation of the T helper cell type 2 (Th2)/T regulatory cell (Treg) balance by IL-4 and STAT6.

During the development of immune responses to pathogens, self-antigens, or environmental allergens, naive CD4(+) T cells differentiate into subsets of effector cells including Th1, Th2, and Th17 cells. The differentiation into these subsets is controlled by specific transcription factors. The activity of these effector cells is limited by nTregs and iTregs, whose differentiation and maintenance are dependent on the transcription factor Foxp3. The regulation of autoimmune diseases mediated by Th1 and Th17 cells by Tregs has been studied and reviewed extensively. However, much less has been presented about the interplay between Tregs and Th2 cells and their contribution to allergic disease. In this perspective, we discuss the regulation of Th2 cells by Tregs and vice versa, focusing on the interplay between the IL-4-activated STAT6/GATA3 pathway and Foxp3.