Oral Presentation 6th Australian Health and Medical Research Congress 2012

UV-induced immune regulation (#162)

Karin Loser 1
  1. University of Muenster, Muenster, NRW, Germany

Cutaneous immunity can be controlled by environmental factors, like UV irradiation, which affects different cell types in the skin such as keratinocytes, epidermal Langerhans cells, and T cells. Langerhans cells, as specialized antigen presenting cells, encounter exogenous antigens, migrate to skin draining lymph nodes, and present skin-acquired antigens to naive T cells resulting in effector T cell differentiation. Effector T cell functions depend on the activation state of Langerhans cells, which can be modulated by UV irradiation in combination with co-stimulatory signals. Besides activating effector T cells, Langerhans cells from UV-irradiated skin have been shown to play a critical role in the peripheral expansion of immunosuppressive regulatory T cells. Notably, co-stimulatory signals via the receptor activator of NF-κB (RANK) and its ligand RANKL seem to connect environmental factors, such as UV irradiation to the immune system since blocking RANK-RANKL interactions abolishes the peripheral expansion of UV-induced regulatory T cells and accordingly, increases skin inflammation in mouse models of contact allergy or autoimmunity and upregulates spontaneous tumor development as well as tumor growth in a model of photocarcinogenesis.