In this project we want to clarify the regulatory mechanisms mediating the T cell repertoire in cutaneaous autoimmunity and examine the control mechanisms necessary for peripheral tolerance in more detail. It is our aim to monitor in a set of autoimmune skin diseases (pemhigus vulgaris (PV), vitiligo, halo naevi, alopecia areata, bullous memphigoid, psoriasis) the regulatory T cell (Treg) frequency and function and to determine it overactivation and expansion of autoreactive T cells override this regulation. Moreover it is our intention to unravel in more detail the role of Tregs in PV disease activity but also to apply it as a model to increase the knowledge about Treg function in general.