ABSTRACT

Th22 cells are recently identified subtype of CD4 T lymphocytes. Naive CD4 T lymphocytes convert to Th1, Th2, Th9, Th17 and Th22 cells according to the cytokines they product. IL-22, a member of IL-10 family, is produced by natural killer (NK), Th17 and Th22 cells. IL-22 receptor complex is composed of IL-22 receptor 1 (IL-22R1) and IL-10 receptor 2 (IL-10R2) units and IL-22 receptor complex is usually expressed on the surfaces of nonhematopoietic cells. IL-22 induces keratinocyte proliferation and epidermal hyperplasia in the skin. IL-22 promotes the production of antimicrobial peptides and chemokines essential for tissue remodeling. IL-22 was initially thought to be released from Th17 cells however it was recently understood that the major part of IL-22 is released from newly identified subtype of T cell as Th22 cells. Th22 cells don’t secrete IL-17 and interferon-γ (İFN-γ), unlike Th17. Th22 cells are located to the skin by chemokine receptors CCR4 and CCR10 and their amount is increased in many skin diseases. In this review, we aim to discuss the role of newly identified subtype of T cells, Th22 cells in skin diseases.