The measurement of staphylococcal protein A by ELISA in immunoglobulin preparations (original) (raw)

Chicken antibodies were used to develop an ELISA for the quant~tatJon of parts-per-milhon levels of protein A in the purification of immunoglobuhns or 0mmunoglobuhn-like molecules Quant~tat~on of prote~n A ~n the presence of excess human or murlne ~mmunoglobuhns ~n this assay was compared with that obtained ~n ELISAs developed w~th rabbit antibodies specific either to prote~n A or to other molecules Experiments demonstrate that protein A is bound to the ~mmunoglobuhns being punfied 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 quantitat~on of th~s protein by ELISA In addition, comparison of the effect of different types of immunoglobuhns on the proteMn A standard curve suggests that alternatives to including the immunoglobulin under punficataon with the standards can be ut~lMzed Materials and methods Reagents Chicken antibodies to protein A, both unconjugated and conjugated to horseradish peroxidase