PROBLEM TO BE SOLVED: To provide a therapeutic and/or prophylactic agent for transplant rejection, immune diseases, allergic diseases, inflammatory diseases, blood clots, cancer etc., targeting human Orai1.SOLUTION: According to the present invention, an antibody or an antigen-binding fragment thereof specifically recognizes human Orai1, and inhibits the amount of IL-2 released from Jurkat cells treated with PMA and A23187 by 50% at the concentration of 80 ng/mL or lower, preferably 10 ng/mL or lower. The antibody or the antigen-binding fragment thereof inhibits the amount of IL-2 released from human peripheral blood mononuclear cells treated with PMA and A23187 by 50% at the concentration of 100 ng/mL or less, preferably 20 ng/mL, and inhibits the amount of IFN-γ by 50% at the concentration of 800 ng/mL or lower, preferably 40 ng/mL or lower.SELECTED DRAWING: None【課題】ヒトＯｒａｉ１を標的とする、移植物の拒絶、免疫疾患、アレルギー性疾患、炎症性疾患、血栓、癌などの治療及び／又は予防剤の提供。【解決手段】ヒトＯｒａｉ１を特異的に認識し、ＰＭＡ及びＡ２３１８７処理されたＪｕｒｋａｔ細胞が放出するＩＬ－２量を５０％阻害する濃度が８０ｎｇ／ｍＬ以下、好ましくは１０ｎｇ／ｍＬ以下である、抗体又は該抗体の抗原結合性断片。亦、ＰＭＡ及びＡ２３１８７処理されたヒト末梢血単核球が方出するＩＬ－２量を５０％阻害する濃度が１００ｎｇ／ｍＬ以下、好ましくは２０ｎｇ／ｍＬ以下であり、ＩＦＮ－γ量を５０％阻外する濃度が８００ｎｇ／ｍＬ以下、好まくは４０ｎｇ／ｍＬ以下である、抗体又は該抗体の抗原結合性断片。【選択図】なし
