Use of protein A-bearing staphylococci for the immunoprecipitation and isolation of antigens from cells.

TLDR: It is found that a variety of antigens can be isolated sequentially from the same radiolabeled cell extract with the appropriate antisera and staphylococci, and has several advantages over the double antibody method.

Abstract: Publisher Summary This chapter describes the use of protein A-bearing staphylococci for the immunoprecipitation and isolation of the antigens from cells. Major developments have been made toward the molecular characterization of a great many cellular and viral proteins. The alternative approach to the precipitation of immune complexes is based on the substitution of chemically fixed, protein A-bearing strains of Staphylococcus aureus bacteria for the secondary antibody. The use of staphylococci for antigen isolation has several advantages over the double antibody method. Specific binding of immune complexes to the staphylococci is extremely rapid, occurring within seconds, and is stable in a variety of solvent systems, whereas nonspecific binding of the other proteins is low. The sequence of the steps for antigen isolation, with the staphylococcal adsorbent, includes the interaction of radiolabeled, solubilized antigen with a molar excess of specific antibody, the binding of immune complexes to the staphylococci, separation from other cell components by centrifuging and washing, and elution from the adsorbent for analysis. It is found that a variety of antigens can be isolated sequentially from the same radiolabeled cell extract with the appropriate antisera and staphylococci.