Monoclonal antibodies have become a general modality in therapeutic development, and a variety of monoclonal antibodies targeting soluble antigens have been developed. However, even with infinite binding affinity to an antigen, a conventional antibody can bind to the antigen only once and results in an increase in total plasma antigen concentration in vivo. This antibody-mediated antigen accumulation generally occurs because the clearance from circulation of an antibody-antigen complex is much s...