A review.A novel, highly directed approach has been developed to overcome the problems of immunogenicity associated with therapeutic proteins.PEGylation is a method, which attempts to eliminate immunogenicity in therapeutic proteins.Polyethylene glycol (PEG) is a neutral, water-soluble non-toxic polymer which has a functional hydroxyl group at either end of the mol. to which proteins can be covalently attached.PEGylated proteins exhibit an increase in half-life and reduction in immune clearance which contribute to improved efficacy.Biovation has developed a novel technol., based on immunol. principles, to directly address the issue of immunogenicity caused by therapeutic proteins.A therapeutic protein can be taken up by an antigen-presenting cell (APC), such as dendritic cell.T cell epitopes are essential to the stimulation of a mature antibody response, and removal of these epitopes from a therapeutic protein can eliminate immunogenicity.