Our proposal aims to unlock the key mechanisms behind two autoimmune diseases, vitiligo and alopecia areata, by focusing on the immunological responses surrounding hair follicles. These diseases affect millions of people worldwide and have a devastating impact on the quality of life. New treatments are emerging although a significant unmet clinical need remains. Our research is focused on understanding the immune system's role in these diseases and developing potential treatments. We will collect samples from patients with vitiligo and alopecia areata to study the immune profiles and the specific immune cells involved in the diseases. Our team will investigate the immune cells involved in the maintenance and failure of the follicular immune privilege (= local protection of hairs against immune attack) in patients with vitiligo and alopecia areata. We will also investigate the adaptive immune receptor repertoire of lymphocytes in the perifollicular skin. Finally, we will identify potential (auto)antigens associated with the etiology of vitiligo and alopecia areata. By identifying specific immune cells and antigens involved in these diseases, we hope to develop more effective and targeted therapies that can improve the lives of millions of people worldwide. Our previous track record in vitiligo and established network of (inter-)national experts ensures the feasibility of this ambitious project.