The skin is an immunologic organ. There are an estimated 20 billion T cells in human skin, far greater than the number of T cells in the blood, suggesting that immune defense in the skin is a high priority. The components of the epidermis and dermis work in concert to execute immune responses in the skin. And it is clear that the epidermis can function as an immunologic organ.
Langerhans cells in the epidermis play a critical roll in the cutaneous immune system. The main function of the epidermis is to regulate epidermal permeability and to act as a physical, chemical, and antimicrobial defense system via the actions of the outermost layer of the epidermis, the stratum corneum. Studies have shown that both stress and gut inflammation can impair the integrity and protective function of the epidermal barrier.(3)
