The measurement of staphylococcal protein A by ELISA in immunoglobulin preparations.
Chicken antibodies were used to develop an ELISA for the quantitation of parts-per-million levels of protein A in the purification of immunoglobulins or immunoglobulin-like molecules. Quantitation of protein A in the presence of excess human or murine immunoglobulins in this assay was compared with that obtained in ELISAs developed with rabbit antibodies specific either to protein A or to other molecules. Experiments demonstrate that protein A is bound to the immunoglobulins being purified and that this binding affects subsequent recognition by the antibodies used for the assay. Because of these effects and because fragments of protein A might not be detected in assays which rely on Fc binding of protein A, chicken antibodies that bind protein A specifically are an advantage for the quantitation of this protein by ELISA. In addition, comparison of the effect of different types of immunoglobulins on the protein A standard curve suggests that alternatives to including the immunoglobulin under purification with the standards can be utilized.
Lucas
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Department of Medicinal and Analytical Chemistry, Genentech Inc., South San Francisco, CA 94080.
Mora-Worms
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Chen
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D000818:Animals; D000911:Antibodies, Monoclonal / Q000302:isolation & purification; D004340:Drug Contamination; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods* / Q000592:standards / Q000706:statistics & numerical data; D006801:Humans; D007074:Immunoglobulin G / Q000302:isolation & purification; D007136:Immunoglobulins / Q000302:isolation & purification*; D012015:Reference Standards; D012680:Sensitivity and Specificity; D013205:Staphylococcal Protein A / Q000032:analysis* / Q000276:immunology
D000911:Antibodies, Monoclonal; D007074:Immunoglobulin G; D007136:Immunoglobulins; D013205:Staphylococcal Protein A