Provided is a novel composition. A composition for cytotoxic T cell depletion, the composition including an anti-LAG-3 antibody or a binding fragment thereof that has the properties described in (i) to (iii): (i) has in vitro ADCC activity; (ii) reduces the number of LAG-3-positive cells in vivo in low-fucose form; and (iii) binds to human activated T cells.本發明之課題係提供一種新穎組成物,其解決手段係一種細胞毒性T細胞耗竭用組成物,其包含具有下述(i)至(iii)記載之性質的抗LAG-3抗體或其結合片段:(i)具有活體外ADCC活性;(ii)在低海藻糖形態下,於活體內使LAG-3陽性細胞數減少;及(iii)與人類活化T細胞結合。