CXCR5(+)CD8(+) Follicular Cytotoxic T Cell Biology and Its Relationship with Diseases

CD8(+) cytotoxic T (CD8(+) T) cells are involved in the elimination of infected and cancerous cells. Functional cell groups of this immune system differentiate into effector and memory subsets to provide long-term protection. Although CD8(+) T cells are rarely recognized as part of germinal center reactions, a new subset of the B cell follicle and germinal center, termed CXCR5(+)CD8(+) follicular cytotoxic T (Tfc) cells, has recently been identified. These cells show a functional profile like CD4(+) T follicular helper cells identified to activate B cells. While their functional mechanisms are largely similar, they control disease pathogenesis differently. Tfc cells check viral load during infection as well as support antibody-associated autoimmune disease progression. This review summarizes the phenotype, function, localization and function of Tfc cells and their relationship with diseases.