Immunochemical characterization and biological properties of a cell surface antigen extracted from encapsulated...

Protection inducing antigen (PIA) was mechanically extracted from Staphylococcus epidermidis (encapsulated strain SE-10) and purified by DEAE-Sephadex A 25 (C1- form) ion exchange chromatography. Major carbohydrate constituents of PIA were galactose, glucose, and N-acetylglucosamine at the molar ratio 1.00:0.96:0.78. Antigenic activity was considerably reduced after sodium metaperiodate oxidation, however, pronase digestion was not effective. N-acetylglucosamine residues were shown to be closely related to the antigenic determinant. No cross reactivity to PIAs from other encapsulated strains of S. epidermidis was found which indicates type specificity. Protection of mice after immunization and enhancement of human granulocyte function suggests that PIA might be considered to be a biological response modifying substance.