The seminal studies Rituximab in ANCA-associated vasculitis (RAVE) [63,64] and Rituximab versus cyclophosphamide in ANCA-associated vasculitis (RITUXVAS) [65] have underlined the relevance of B cells, as targeting B cells by treatment with rituximab, a monoclonal antibody directed against CD20-bearing cells, has become mainstay in the management of PR3- and MPO-ANCA vasculitis. This evidence concerns the gene MPO and anti-neutrophil cytoplasmic antibody-associated vasculitis.