95 FcyRlIb-SPECIFIC Fc ANTIBODY ABSTRACT5 An objective of the present invention is to provide a polypeptide containing an Fcregion having maintained or decreased binding activities towards both allotypes of EcyRIIa, types H and R, and having enhanced FeyRIlb-binding activity in comparison with a parent polypeptide； a pharmaceutical composition containing the polypeptide； an agent for treating or preventing immunological inflammatory diseases that includes the pharmaceutical composition； 10 a production method thereof and a method for maintaining or decreasing binding activities towards both allotypes of FcyRIIa and enhancing the FcyRIIb-binding activity. Specifically, it is found that a polypeptide containing an antibody Fc region that has an alteration of substituting Pro at position 238 (EU numbering) with Asp or Leu at position 328 (EU numbering) with (flu enhances FcyRIIb-binding activity, and maintains or decreases binding activities towards both 15 allotypes of FcyRlIa, types H and R. It is also found that a polypeptide containing an antibody Fc region that contains an alteration of substituting Pro at position 238 (EU numbering) with Aspand several other alterations, enhances FcyRIlb-binding activity, and maintains or decreases binding activities towards both allotypes of FcyRIIa, types H and R. 20 (No Suitable Figure)
