Polyethylene glycol (PEG) chains are often used to modify therapeutic biologic agents in order to prolong the circulating half-life of the modified protein by slowing proteolytic degradation. It has been reported that repeat injections of PEGylated proteins can induce anti-PEG antibodies. Anti-PEG antibodies can result in rapid clearance and decreased drug efficacy (accelerated blood clearance, or ABC, phenomenon). PRINCIPLE OF THE ASSAY This immunogenicity assay measures the presence of human IgG in serum or plasma that bind to immobilized PEG using the direct ELISA technique. The supplied stretavidin precoated 96 well microplate is incubated with biotinylated PEG (5KDa). After washing, quality control and test samples are pipetted into the appropriate wells. Anti-PEG antibodies bind the immobilized PEG. After washing, detection antibody (anti human IgG Peroxidase) is added. Any unbound antibody enzyme reagent is removed with a final wash and a substrate solution is added to the wells for color development. Color development is proportional to the amount of anti-PEG IgG. Range: 250ng/ml-62.5ng/ml. Time: 3.5 hours.