A New Immunoenzyme Tracer for Localization of Antibodies in Immunohistology: Peroxidase-Labeled Protein A

Abstract

Protein A from Staphylococcus aureus, characterized by high affinity binding properties for IgG-type antibodies, was labeled with horseradish peroxidase to form a stable immunohistological tracer molecule of comparatively low MW. It was used for demonstration of [human] antibodies against tissue antigens, in direct and indirect technqiues, and the findings were consistent with those in routine immunofluorescence and in staining with peroxidase-coupled anti-IgG. The lowest unspecific tissue adsorption and staining were obtained with protein A-peroxidase in buffer containing glucose, galactose and mannose. The immunohistological preparations were mounted and stored for documentation without apparent loss of staining.