Patent ID: 7511121

Claim:
A polypeptide with an immunoglobulin framework consisting of an Fc region linked to two arms; wherein each arm consists of an HCH2 polymer linked to a protein or portion thereof; the HCH2 polymer consists of two to six linear copies of an HCH2 monomer; the HCH2 monomer consists of at least a portion of an HCH2 region of human IgG1 or at least a portion of an HCH2 region of human IgG3, wherein the at least a portion of an HCH2 region of human IgG1 and the at least a portion of an HCH2 region of human IgG3 include a hinge region; at least one hinge region cysteine of the HCH2 monomer is mutated to serine; and the polypeptide targets to cells expressing low affinity FcÎ³R, or binds to low affinity FcÎ³R.