Clinical transplantation of skin remains an unsolved problem. The rejection process is a rapid one and high doses of immunosuppressive drugs are needed to mitigate it, bringing about systemic complications in the recipient. The strong response of skin cells to alloantigens is dictated by their evolutionarily developed innate reaction to the penetrating microorganisms. The details of this mechanism are still unclear. The understanding of immune processes in a transplanted skin requires more knowledge of the physiological functional relationship between the keratinocytes, Langerhans cells, macrophages, fibroblasts and endothelial cells and their receptors and humoral products. Transplanted skin is a site of hostversus- graft and graft-versus-host reaction.

Keywords: Skin, Epidermis, Physiology, Transplantation, Toll-Like Receptors