Immunoassay to measure staphylococcal protein A in the presence of murine immunoglobulins.
Immunoassays designed to measure low concentrations of staphylococcal protein A are subject to varying degrees of interference by excess IgG. We have developed an enzyme-linked immunosorbent assay (ELISA) that overcomes this problem by analyzing IgG-containing protein A samples in solutions buffered at pH 3.5. Under these carefully selected conditions, protein A is absorbed efficiently by solid-phase chicken anti-protein A antibodies, but protein A-IgG complexes are largely dissociated. The assay has a protein A detection limit of 0.1 ng/ml, and the response is unaffected by 0.25 mg/ml murine IgG. The method should be useful for determining protein A contamination levels in antibodies purified by affinity chromatography on immobilized protein A resins.
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Repligen Corporation, Cambridge, MA 02139.
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D000818:Animals; D002645:Chickens; D002852:Chromatography, Ion Exchange; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods*; D006863:Hydrogen-Ion Concentration; D007074:Immunoglobulin G / Q000737:chemistry*; D011485:Protein Binding; D011994:Recombinant Proteins; D015203:Reproducibility of Results; D013205:Staphylococcal Protein A / Q000032:analysis* / Q000302:isolation & purification
D007074:Immunoglobulin G; D011994:Recombinant Proteins; D013205:Staphylococcal Protein A