Lupus nephritis (LN) and ANCA-associated vasculitis are severe autoimmune diseases, which may lead to the death of patients, particularly when they are refractory to the conventional therapeutic agents. Based on the current knowledge, the autoantibodies against self-antigens may exert important pathological roles in the pathogenesis of both LN and ANCA-associated vasculitis, of which the origins are primarily plasmablasts and plasma cells. BCMA is the molecule expressed on memory B cells, plasmablasts and plasma cells, and therefore is an ideal target for the elimination of potential pathogenic antibody secreting cells. Chimeric antigen receptor (CAR) T cells against BCMA may provide a novel therapeutic way for the refractory LN and ANCA-associated vasculitis patients to eliminate the pathogenic autoantibody-secreting cells. In this study, the safety and efficacy of a novel CAR-T cell therapy using PRG-1801 cells, are evaluated in patients with refractory LN and ANCA-associated vasculitis.