Follicular T helper cells are a specialized subtype within the CD4+ T helper cells. T-helper cells (Th cells) coordinate the cellular and humoral immune response against various pathogens. Thus, follicular T helper cells (Tfh cells) are essential for the production of highly potent antibodies by B cells. If Tfh cells get out of control, this can cause autoimmunity and allergies. Apparently, Tfh cells also play a role in other Th cell-mediated immune responses, e.g. in the generation of certain effector and memory Th cells. However, the exact relationship between Tfh and other Th cell die subpopulations remains unknown.