INTERACTIONS BETWEEN EPITHELIAL-CELLS AND THE IMMUNE-SYSTEM

Such interactions must be envisaged in the concept of the lymphoid system associated with the skin and the cutaneous immune system. Skin contains cells and humoral factors which are responsible for immune reactions involved in various physiological and pathological events (defence against infections, defence against foreign allergens, cutaneous inflammatory and lymphomatous process). Keratinocytes produce various cytokins which are more than interleukins and which participate in cutaneous immune and inflammatory reactions. They include in particular epidermal cytokins (interleukin 1, interleukin 3, interleukine 6 in particular and other cytokins such as factors which stimulate granulomatous colonies) and less well differentiated soluble factors or mediators which act upon differentiation or activation or which are inhibitors of immune responses. These various factors, produced by human and animal keratinocytes, have several possible targets, whether cells belonging to the immune system or other cells, dermal fibroblasts in particular. This is the case for interleukin 1 but also other soluble mediators. Finally, the authors point out the participation of and experimental data concerning these factors in various processes: healing (epidermal and dermal), inflammation and inflammatory skin disorders and T cell skin lymphomas.