Provided are methods for treatment or prevention of an autoimmune disease that comprise administering a monoclonal antibody or a binding fragment thereof that binds to domain 3 of human LAG-3 and has one or more of the properties described in (ii) to (v), and the properties described in (i) and (vi) below: (i) having in vitro ADCC activity; (ii) reducing the number of LAG-3 positive cells in vivo in low fucose form; (iii) suppressing experimental autoimmune encephalomyelitis in vivo in low fucose form; (iv) binding to human activated T cells; (v) human LAG-3 binds to human major histocompatibility complex class II molecules in the presence of the antibody or the binding fragment thereof; and (vi) the presence of the antibody or the binding fragment thereof allowing human LAG-3 to exert a human T cell suppression function.