Flow cytometry analysis of anti-polyethylene glycol antibodies in human plasma

Polyethylene glycol (PEG) is a biocompatible polymer used in biotherapeutics to increase bioavailability, reduce the frequency of administration, and optimize pharmacokinetics. Anti-PEG antibodies have been detected in healthy individuals and may decrease efficacy and alter the pharmacokinetics of PEGylated therapeutics; however, the prevalence of anti-PEG antibodies is unclear. In this study, a flow cytometry assay was optimized to detect anti-PEG IgG and IgM in human blood plasma. Three hundred (300) plasma samples from healthy blood donors were screened; anti-PEG IgG or IgM was detected in 65.3% of the total population, with 21.3% having anti-PEG IgG, 19.0% having anti-PEG IgM, and 25.0% having both anti-PEG IgG and IgM. The presence of anti-PEG IgG and IgM was confirmed using a 0.5% Tween-20 interference assay, a 20 kDa PEGylated polystyrene bead binding assay, and Western blotting of purified plasma from human IgG and IgM purification columns. The concentrations of anti-PEG IgG and IgM in positive samples ranged from 39 ng/mL to 18.7 μg/mL and 26 ng/mL to 11.6 μg/mL, respectively. The highest prevalence of both anti-IgG and anti-IgM was in individuals 18-24 years of age. The prevalence of anti-PEG IgG and IgM tended to be higher in women but did not differ among races. Age, sex, and race were not associated with the concentrations of anti-PEG IgG or IgM. No correlation was found between anti-PEG IgG and IgM concentrations. Our study indicates that flow cytometry can be used to detect anti-PEG IgG and IgM antibodies in human plasma.