A BLAST of sunshine doesn鈥檛 just ward off depression. It could also help fight skin cancer and other skin diseases by attracting immune cells to the skin surface.
Skin produces the inactive form of vitamin D3 in response to sun exposure. Now Eugene Butcher of Stanford University in California and his colleagues have shown that immune cells in the skin known as dendritic cells convert the inactive vitamin D3 into its active form.
The active form then causes T-cells 鈥� immune cells that destroy damaged and infected cells, and regulate other immune cells 鈥� to change the receptors on their surfaces to enable them to migrate to the upper layers of the skin. Here they can help repair sun-induced damage and fight off pathogens (Nature Immunology, DOI: 10.1038/ni1433).
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鈥淪unshine is good for you, as long as it鈥檚 not too much,鈥� says team member Hekla Sigmundsdottir. She says the finding may help explain the success of vitamin D3 skin creams for conditions like psoriasis: the creams attract T-cells to the skin, where they can fight inflammation.
The finding also adds to a growing body of evidence that dendritic cells, which live in tissues exposed to the external environment, such as those in the skin and nose, act as traffic controllers for the immune system, interpreting local conditions and directing T-cells to where they are needed.
