The skin as an immunological organ
Bjerke, J.R.
Tidsskrift for den Norske Laegeforening Tidsskrift for Praktisk Medicin Ny Raekke 122(8): 793-796
2002
ISSN/ISBN: 0029-2001 PMID: 12092071 Document Number: 544900
The skin is our largest organ. Its physico-chemical properties are adapted to its function as a non-specific general defense line against infections and injury from the environment. Through evolution the skin has developed a second line of highly specific immune defense comprising epidermal Langerhans cells, T lymphocytes and keratinocytes as the most distinct cellular elements. On the basis of available research data and reviews, an overview on the skin as an immunological organ is presented. Antigens penetrating into the epidermis are bound to dendritic Langerhans cells, processed and presented to T lymphocytes. Certain memory T cells are able to remember where they first encountered antigen. Skin homing T cells are CLA+ and circulate between the skin, peripheral blood and skin draining lymph nodes. Keratinocytes produce a wide spectre of cytokines, in particular interleukin-1, which has a key role in the skin immune function. The most common inflammatory skin disorders are mediated by T lymphocytes, usually Th1 cells, as in psoriasis, or Th2 cells, as in atopic dermatitis. Systemic treatment with T cell specific suppressive drugs, such as cyclosporine, has been successful in certain dermatoses. Promising cyclosporine analogues for topical treatment (tacrolimus and pimecrolimus) have been developed and may soon be introduced.