ABSTRACT
Background: Polyethylene glycols (PEGs) are hydrophilic polyethers widely used in pharmaceutical, cosmetic, food, and household products. PEG is usually safe and allergic reactions are rare, however according to literature, hypersensitivity is most likely underestimated and mild to life-threatening immediate-type hypersensitivity to PEG have been reported. PEG 2000 is an ingredient in some of the COVID-19 vaccines and is a possible cause of rare cases of adverse reactions to the vaccines that have been reported*. PEG hypersensitivity seems to depend on molecular weight (MW) and higher MW PEGs appear to be more allergenic. Based on this, we developed two ImmunoCAP PEG tests with different MW:s of PEG for measurement of anti-PEG specific IgE (sIgE) and specific IgG antibodies. Method(s): ImmunoCAP PEG 2000 and PEG 10000 Research Use Only (RUO) tests were developed according to conventional methods. As PEG is structurally related to polysorbates, a specific polysorbate 20 free washing solution was developed. The analytical characteristics of the ImmunoCAP PEG tests have been determined and an accelerated stability study has been performed. Result(s): The developed RUO ImmunoCAP PEG 2000 and PEG 10000 tests fulfilled internal standard RUO specifications using the polysorbate 20 free washing solution. Intra-and inter assay performance were evaluated at three concentrations from low to high on the sIgE measuring range (0-100 kUA/L). Overall results for intra-and inter assay performance were <=6.0 %CV and <=9.5 %CV, respectively. Anti-PEG IgG have been reported in human plasma samples with levels reaching up to 6.5 mug/mL (median 49.3 ng/mL). No anti-PEG IgG interference could be detected for these PEG tests when assayed with an anti-PEG IgG positive control in concentrations up to 6.5 mug/mL. An accelerated stability study indicated a shelf-life of two years for both PEG tests. Conclusion(s): Two ImmunoCAP PEG tests have been developed. These tests have been used as a complementary research tool to evaluate the risk for hypersensitivity reactions to PEG and to determine sIgE sensitization pattern in patient serum. In addition, studies have shown sIgE levels >0.1 kUA/L using these ImmunoCAP PEG tests for patients with a history of reactions to PEG together with positive skin prick testing. *It is important to understand that these reactions are extremely rare and should not discourage the general public from vaccination.