Provided is a novel antibody. According to the present invention, a monoclonal antibody or a binding fragment thereof binds to domain 3 of a human LAG-3, and has the properties described in (i) and (vi) and one or more of the properties described in (ii) to (v) below: (i) the antibody has in vitro ADCC activity； (ii) the antibody is a low-fucose antibody and reduces the number of LAG-3 positive cells in vivo； (iii) the antibody is a low-fucose antibody and suppresses experimental autoimmune encephalomyelitis in vivo； (iv) the human LAG-3 binds to a human activated T cell； (v) the human LAG-3 binds to a human major histocompatibility gene complex class II molecule in the presence of the antibody or a binding fragment thereof； and (vi) the human LAG-3 exhibits a human T cell suppression function in the presence of the antibody or a binding fragment thereof.本發明的課題係提供一種新穎抗體。本發明的解決手段係提供一種單株抗體或其結合片段，其結合至人類LAG-3的域(domain)3，且具有下述(ii)至(v)所記載的性質中之一個以上、以及(i)及(vi)所記載的性質：(i)具有體外ADCC活性；(ii)以低海藻糖形態，於活體內使LAG-3陽性細胞數量減低；(iii)以低海藻糖形態，於活體內抑制實驗性自體免疫性腦脊髓炎；(iv)結合至人類活化T細胞；(v)在該抗體或其結合片段存在下，人類LAG-3與人類主要組織相容性複合體第二型(class II)分子會結合；及(vi)在該抗體或其結合片段存在下，人類LAG-3發揮人類T細胞抑制功能。
