The present invention demonstrated that the modification of the Fc region of an antigen-binding molecule into an Fc region that does not form in a neutral pH range a heterotetramer complex containing two molecules of FcRn and an active Fcγ receptor improved the pharmacokinetics of the antigen-binding molecule and reduced the immune response to the antigen-binding molecule. The present invention also revealed methods for producing antigen-binding molecules having the properties described above, and successfully demonstrated that pharmaceutical compositions containing as an active ingredient such an antigen-binding molecule or an antigen-binding molecule produced by a production method of the present invention have excellent features over conventional antigen-binding molecules in that when administered, they exhibit improved pharmacokinetics and reduced in vivo immune response.
