The Study Of Characteristics And Mechanism Of EGCG On Reducing Apoptosis Rate Of Langerhans Cells After UVB Irradiation

Background and object:More than 25 years have passed since the discovery that ultraviolet (UV) radiation can affect the immune system. Since then numerous studies in the field of photoimmunology have tried to identify the biological impacts of UV-induced immunosuppression and precancerous lesion even skin cancer. The immuno suppressive effects of solar radiation are mediated mostly by the middle wave length range (UVB, 280-320 nm). There is also recent evidence that the long wave range (UVA, 320-400 nm) can affect the immune system although its effects are less pronounced.Langerhans cell is an idiographic type of dendritic cells. Since Langerhans cells are the major antigen presenting cells in the skin and they play important roles in the immune system, they are the main target cells of immunosuppression induced by UVB. Depending on the UV dose applied, the disappearance of Langerhans cells may be due to the emigration of Langerhans cells out of the epidermis since Langerhans cells harbouring UV-mediated DNA damage can be detected in the draining lymph nodes. All of these approve the injury of LC conducted by UVB. LC is rare in the skin — only 2% ~ 5% of the total epidermal cells and hard to be isolated and purified. CDla is Langerhans cells-specific marker and is used to...