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Abstract

T follicular helper (Tfh) cells are a new subset of CD4+ T cells located in tonsils and circulating in the blood. Thf cells are required for maintenance of the germinal center reactions and generation of humoral immunity via their expression of many molecules as CD40 ligand, IL-21, IL-4, and others. Tfh cells provide the help to B-cells to differentiate to plasma cells. It has a unique phenotype CXCR5+ and express a master regulator BCL-6.