Disclosed are: a genetically recombinant antibody composition which has a CH2 domain having the substitution of an amino acid residue at position-276 and position-339 numbered according to the EU index as in Kabat et al. in a human IgG1 antibody and has an enhanced complement-dependent cytotoxicity compared to an antibody having a CH2 domain without any amino acid residue substitution therein； an antibody molecule contained in the genetically recombinant antibody composition, or DNA encoding a heavy-chain constant region of the antibody molecule； a transformant produced by introducing the DNA into a host cell； a method for producing a genetically recombinant antibody composition by using the transformant； and a pharmaceutical agent comprising the genetically recombinant antibody composition as an active ingredient.
