T follicular helper and TH2 cells in allergic responses

IL-4 is a cytokine commonly secreted by T(H)2 and follicular helper T (T-FH) cells after antigenic sensitization. T(H)2 cells have been thought to be the major contributor of B cell help as a source of IL-4 responsible for class switch recombination to Immunoglobulin G1 (IgG1) and Immunoglobulin E (IgE). Importantly, there are some differences in transcriptional regulation between these two T cell subsets. The IL-4 production by T(H)2 and TFH cells is distinctively regulated by two pathways, GATA-3-mediated Il4-HS2 enhancer and Notch mediated Il4-CNS-2 enhancer. IgE and IgG1 antibody responses are mainly controlled by IL-4-secreting TFH cells, but not by T(H)2 cells. In this review, we discuss the role of TH2 and T-FH cells in IgE production and allergic responses. Copyright (C) 2017, Japanese Society of Allergology. Production and hosting by Elsevier B.V.