Franco Di Padova
Editors 2013 The IL-17 cytokines represent a novel family of cytokines, which extends the Th1-Th2 paradigm and defines a new effector T cell, the Th17 cell. Th17 cells may co-express at least IL-17A and IL-17F and IL-22. IL-17A and IL-17F can be produced by CD4þ T cells (Th17 cells), CD8þ T cells (Tc17), gd T cells, iNKT, NK cells, lymphoid tissue inducers cells, innate lymphoid cells, mast cells, neutrophils and Paneth cells. IL-17F can be expressed also by epithelial cells. IL-22 can be produced by CD4þ T cells (Th22) as well as other cell types. The regulation of IL-17 family members and the effector cells and mechanisms are an area of intense current research, and include as an example the nuclear receptors RORgt and proinflammatory cytokines such as IL-1, IL-6, TGFb, IL-21 and IL-23.