Effects of ultraviolet radiation on Langerhans cells

Research on penetration of ultraviolet (UV) radiation into human skin shows that about 20% of UVA and 10% of UVB can reach the basal layer of the epidermis. As a consequence, Langerhans cells (LCs), located in suprabasal layers, are subject to the influence of the two types of UV radiation. This phenomenon leads to quantitative and qualitative alterations in LCs, including reduction in their number in the epidermis and modifications in morphology and immune functions. Studies show that two mechanisms may be responsible for their depletion from epidermis, namely, migration to the lymph nodes or induction of cell necrosis or apoptosis. UV radiation also affects the phenotype of LCs and their functions as antigen presenting cells. In recent years, the role of LCs in the UV-dependent immunosuppression and immune tolerance has been emphasized. The aim of the study is to review the literature about the influence of ultraviolet radiation on Langerhans cells.