Anti-IL-5 Therapy in Bullous Pemphigoid (BP)

Inclusion Criteria: * Men, women \>18 years * Active BP (diagnosed by typical clinical picture and skin biopsy) * Must give written informed consent Exclusion Criteria * Patients with other skin disease * Patients with severe diseases of other organ systems * Systemic treatment for BP * Topical therapy with corticosteroids and other anti-inflammatory substances * For female patients, unless postmenopausal or surgically sterile, unwillingness to practice effective contraception (defined as methods with \<1% failure rate) * Female patients who are currently pregnant or breast-feeding * Current abuse of alcohol and/or drugs * History of or a new diagnosis or treatment of an invasive malignancy within 5 years of enrollment. Patients with a history of treated squamous cell and/or basal cell carcinomas limited to the skin are not excluded. * History of recurrent clinically significant infection * Congenital or acquired immunodeficiency syndrome * Current enrollment in any other investigational drug study * Previous participation in this study or previous studies with mepolizumab * Hypersensitivity to mepolizumab or its constituents