Bullous pemphigoid (BP) is the most frequent autoimmune skin disease and mainly affects elderly individuals. BP classically manifests with tense blisters over urticarial plaques on the trunk and extremities accompanied by intense itches. However, BP is characterized by a large spectrum of clinical presentations allowing to distinguish between typical (with blisters) and atypical forms (non bullous, mucosal damage). High potency topical steroids and systemic steroids are the current first line intention treatments. While very efficient, these therapies are non-targeted and cause numerous side-effects, especially in these elderly patients that are the most affected. Furthermore, around 30% of BP patients will relapse during the first year of treatment when corticotherapy is decreased or stopped. The investigators and others have highlighted the presence of Il-17 family belonging-inflammatory cytokines in BP patients. Their functions in the amplification of the inflammatory response and in the mechanisms of relapse have to be precisely determined in order to develop innovative therapeutic approaches and to move forwards precision medicine.