Functional differentiation and regulation of follicular T helper cells in inflammation and autoimmunity

Summary Follicular T helper (TFH) cells are specialized T cells that support B cells, which are essential for humoral immunity. TFH cells express the transcription factor B‐cell lymphoma 6 (Bcl‐6), chemokine (C‐X‐C motif) receptor (CXCR) 5, the surface receptors programmed cell death protein 1 (PD‐1) and inducible T‐cell costimulator (ICOS), the cytokine IL‐21 and other molecules. The activation, proliferation and differentiation of TFH cells are closely related to dynamic changes in cellular metabolism. In this review, we summarize the progress made in understanding the development and functional differentiation of TFH cells. Specifically, we focus on the regulatory mechanisms of TFH cell functional differentiation, including regulatory signalling pathways and the metabolic regulatory mechanisms of TFH cells. In addition, TFH cells are closely related to immune‐associated diseases, including infections, autoimmune diseases and cancers.