Immunopathogenesis and role of T cells in psoriasis.

Psoriasis is a T cell-dependent autoimmune disease of the skin and joints. Disease manifestation is orchestrated by proinflammatory CD4-positive T helper cells producing either interferon-gamma (Th1) or interleukin (IL)-17 (Th17). These Th1 and Th17 cells interact with dermal dendritic cells, macrophages, mast cells, and neutrophils. Together, they cause an inflammation that mainly involves interferon-gamma, tumor necrosis factor, IL-8, IL-12, IL-17, IL-19, and IL-23. New therapeutics either are directed against T cells, tumor necrosis factor, and IL-12/IL-23 or deviate immune responses into a protective IL-4-dominated Th2 phenotype.