An objective of the present invention is to provide methods for facilitating
antigen-binding molecule-mediated
antigen uptake into cells, methods for facilitating the reduction of
antigen concentration in
plasma, methods for increasing the number of antigens to which a single antigen-binding molecule can bind, methods for improving
pharmacokinetics of antigen-binding molecules, antigen-binding molecules improved for facilitated
antigen uptake into cells, antigen-binding molecules capable of facilitating the reduction of antigen concentration in
plasma, antigen-binding molecules capable of repeatedly binding to antigens, antigen-binding molecules with improved
pharmacokinetics, pharmaceutical compositions comprising such an antigen-binding molecule, and methods for producing those described above. The present inventors discovered that
antigen uptake into cells is facilitated by an
antibody having human FcRn-binding activity at the
plasma pH and a lower antigen-binding activity at the early endosomal pH than at the plasma pH; such antibodies can increase the number of antigens to which a single
antibody molecule can bind; the reduction of antigen in plasma can be facilitated by administering such an
antibody; and antibody
pharmacokinetics can be improved by using such antibodies.