Figures & data
Figure 1 UVB rays from sunlight generates vitamin D3 from its precursor in the skin. Vitamin D3 is not very active and can be converted to both 25(OH)D3 and 1,25(OH)2D3 by dendritic cells. Dendritic cells come in close contact with T cells, and in the presence of vitamin D3, the CCR10 receptor is induced on the T cells. This attracts the T cells to CCL27, which is selectively produced and secreted by keratinocytes in the epidermis. Thus, once T cells have infiltrated the dermal layers of the skin from the cutaneous blood vessel, they can be mobilized within the skin and migrate to the epidermis. This way, T cells could be drawn to the epidermis when they are needed.
