The present inventors generated modified antibodies in which several Fc domains are linked in tandem to the C terminus of the heavy chain, and modified antibodies in which Fc domains are linked in tandem via spacers, and measured the affinity for Fc receptors, CDC activity, and ADCC activity. A previous report indicated that CDC activity is not enhanced by linking multiple Fcs. However, the modified antibodies of the present invention exhibited enhanced ADCC activity. The methods of the present invention enable provision of antibody pharmaceuticals having a marked therapeutic effect.
