A comparison of three immunoperoxidase techniques for antigen detection in colorectal carcinoma tissues

We compared the streptavidin-peroxidase conjugate (SP) method of immunoperoxidase histochemistry to the unlabeled antibody (PAP) and avidin-biotin-peroxidase complex (ABC) techniques in human colorectal carcinoma tissues stained with a monoclonal antibody for expression of carcinoembryonic antigen. Compared to the ABC and PAP method, the SP method produced stronger staining intensity and very low background staining. This was true when other antibody isotypes, other antibody species, other organs, and another tumor-associated antigen were used. Moreover, the SP procedure time could be reduced to one third that of the ABC or PAP methods without compromising accuracy, and the SP reagent is stable for several months. The chemical nature of the streptavidin molecule accounts, in large part, for the advantages of the SP method.