Patent ID: 7597889

Claim:
A binding molecule which is a recombinant polypeptide comprising: (i) a binding domain capable of binding a target molecule, which binding domain is the binding site of an antibody, and (ii) an effector domain having an amino acid sequence homologous to a constant domain of a human immunoglobulin heavy chain; wherein the binding molecule is capable of binding the target molecule without triggering significant complement dependent lysis, or cell mediated destruction of the target, and the effector domain is capable of specifically binding FcγRIIb and optionally FcRn, and wherein the effector domain comprises a chimeric C H 2 domain which is derived from two or more human immunoglobulin heavy chain C H 2 domains, which human immunoglobulins are selected from IgG1, IgG2 and IgG4, and wherein the effector domain has a reduced affinity for FcγRI, FcγRIIa and FcγRIII and a reduced ability to mediate complement lysis by comparison with said constant domain of a human immunoglobulin heavy chain and wherein the chimeric C H 2 domain is a human immunoglobulin heavy chain C H 2 domain which has the following blocks of amino acids at the stated positions: 233P, 234V, 235A, 236G, 327G, 330S and 331S numbered with respect to the EU numbering system of Kabat, and is at least 98% identical to G1 Δac (SEQ ID NO:3) or G4 Δc (SEQ ID NO:12) as shown in FIG. 17 .