PROBLEM TO BE SOLVED: To provide antibodies for preventing or treating B cell chronic lymphocytic leukemia, non-Hodgkin's lymphoma, autoimmune disorders, inflammatory disorders, IgE mediated allergic disorders etc.SOLUTION: The invention provides an anti-FcγRIIB antibody and an antigen-binding fragment thereof that specifically bind to an extracellular domain of native human FcγRIIB with a higher affinity than to the native human FcγRIIA, as well as an antibody comprising amino acid modifications in the Fc domain to alter the effector functions, and an antibody conjugated to a therapeutic material.SELECTED DRAWING: None【課題】B細胞慢性リンパ性白血病、非ホジキンリンパ腫、自己免疫障害、炎症性障害、IgE媒介アレルギー障害等の予防、治療抗体の提供。【解決手段】ネイティブなヒトFcγRIIAに結合する場合より大きな親和性で、ネイティブなヒトFcγRIIBの細胞外ドメインに特異的に結合する抗FcγRIIB抗体、その抗原結合断片、エフェクター機能を変更するためにFcドメインにアミノ酸改変を含む抗体、治療物質に結合した抗体の提供。【選択図】なし
