Follicular helper T cells and their application in immune diseases

Follicular helper T (Tfh) cells are a type of newly discovered independent subgroup of CD4⁺T lymphocytes under the control of B cell lymphoma 6 protein (Bcl-6), which are characterized by high expression of C-X-chemokine receptor type 5 (CXCR5), inducible co-stimulator (ICOS), programmed cell death protein (PD-1) and interleukin (IL)-21. The function of Tfh is to assist B lymphocytes to activate, proliferate and differentiate into plasma cells in the germinal center lymphatic follicles, so as to produce high-affinity immunoglobulin, and promote the classification conversion of Ig subgroups and the formation of memory B cells. Previous studies have shown that Tfh dysfunction is closely related to immunodeficiency disease, allergy, tumor, organ transplant rejection and heart disease. In recent years, it has been confirmed that Tfh also plays an important role in the pathogenesis of autoimmune diseases. This article reviews the origin, differentiation, transcriptional regulation of Tfh and its relationship with autoimmune diseases such as systemic lupus erythematosus, rheumatoid arthritis, primary Sjögren's syndrome and type 1 diabetes.