“Protein A” from S. Aureus I. Pseudo-Immune Reaction with Human γ-Globulin

Protein A was isolated from S. aureus and shown to precipitate about 45% of a pooled normal human γG preparation. In addition it was demonstrated that protein A reacts with myeloma γG-globulin, H chains from both normal and myeloma γG-globulins and the Fc fragment of normal γG-globulin. Thus, the reaction is not a true antigen-antibody reaction.