PROBLEM TO BE SOLVED: To provide antibodies or fragments thereof that are immunoreactive to the mammalian, more specifically, the human B7-H3 receptor, and methods for using them in the treatment of cancer and inflammation.SOLUTION: Provided is a dual affinity retargeting reagent comprising: (A) polypeptide chain I comprising an immunoglobulin VL epitope-binding domain that specifically binds B7-H3 and a VH epitope-binding domain that specifically binds a molecule other than B7-H3; and (B) polypeptide chain II comprising an immunoglobulin VH epitope-binding domain that specifically binds B7-H3 and a VL epitope-binding domain that specifically binds a molecule other than B7-H3, where the polypeptides I and II associate to form a functional epitope binding domain capable of binding B7-H3 and a functional epitope binding domain capable of binding a molecule other than the B7-H3, and the reagent comprises at least a part of an Fc region.SELECTED DRAWING: Figure 23【課題】哺乳類、より詳しくは、ヒトB7-H3受容体と免疫反応性のある抗体およびそれらのフラグメント、ならびに特に癌および炎症の治療におけるそれらの使用方法の提供。【解決手段】(A)B7-H3との結合に特異的な免疫グロブリンVLエピトープ結合ドメイン、及びB7-H3以外の分子との結合に特異的なVHエピトープ結合ドメインを含む、ポリペプチド鎖I、及び(B)B7-H3との結合に特異的な免疫グロブリンVHエピトープ結合ドメイン、及び前記B7-H3以外の分子との結合に特異的なVLエピトープ結合ドメインを含む、前記ポリペプチド鎖IとIIがともに会合して、B7-H3と結合可能な機能的エピトープ結合ドメイン及び前記B7-H3以外の分子と結合可能な機能的エピトープ結合ドメインを形成し、Fc領域の少なくとも一部を含む、二重親和性再標的化試薬。【選択図】図23