A review.Several proteins of any origin, including human proteins, when administered as therapeutics could elicit an immune response.Immunogenicity can reduce the efficacy of a biol. by lowering the mol.'s half-life in the circulatory system due to rapid clearance by immune cells.Thus, the immunogenicity observed with some therapeutic proteins is recognized as a barrier to further development of those mols. for clin. use.A number of techniques have been developed to address the issue of immunogenicity from therapeutic proteins.These include PEGylation, humanization of therapeutic proteins, and identifying and removing T-cell epitopes.