PROBLEM TO BE SOLVED: To provide antigen binding molecules promoting antigen uptake into cells and promoting reduction of antigen concentration in plasma, and to provide pharmaceutical compositions comprising the antigen binding molecules, and production methods of the same.SOLUTION: There are provided antibodies whose antigen binding activity in the pH in early endosome is weaker in comparison to the antigen binding activity in the pH in plasma, and having human FcRn binding activity in the pH in plasma. There are provided antigen binding molecules comprising antigen binding domain and human FcRn binding domain, which have human FcRn binding activity in the pH neutral region, and whose human FcRn binding activity in the pH neutral region is stronger than KD 3.2 μM.EFFECT: The antibodies promote antigen uptake into cells, and increase the number of antigens to which a single molecule antibody can bind. Reduction of antigens in plasma is promoted by administering the antibodies, and pharmacokinetics of antibodies can be improved by using the antibodies.SELECTED DRAWING: None【課題】抗原の細胞内への取込の促進及び血漿中の抗原濃度の減少を促進する抗原結合分子、前記抗原結合分子を含む医薬組成物、及びそれらの製造方法の提供。【解決手段】血漿中でのｐＨにおける抗原結合活性と比較して早期エンドソーム内でのｐＨにおける抗原結合活性が弱く、かつ血漿中でのｐＨにおけるヒトＦｃＲｎ結合活性を有する抗体。抗原結合ドメインとヒトＦｃＲｎ結合ドメインとを含む抗原結合分子であって、ｐＨ中性域においてヒトＦｃＲｎ結合活性を有し、ｐＨ中性域におけるヒトＦｃＲｎ結合活性がＫＤ ３．２μＭより強い、前記抗原結合分子。【効果】前記抗体は、抗原の細胞内への取込を促進し、１分子の抗体が結合できる抗原の数を増加させることができ、そのような抗体の投与により血漿中の抗原減少を促進することができ、前記抗体の使用により抗体の薬物動態を改善することができる。【選択図】なし
