Staining enhanced polymer one-step

Rapid immunohistochemical study of frozen sections is necessary for intraoperative diagnosis in some cases. Rapid immunostaining is also helpful in confirming or excluding tumor clearance in resection margins or in detecting micrometastases in sentinel lymph nodes in breast cancer patients. Two methods to immunostain frozen sections are the enhanced polymer one-step staining (EPOS) system and the EnVision system both systems are detailed later. 

Tsutsumi, Y., Serizawa, A., and Kawai, K. 1995. Enhanced polymer one-step staining (EPOS) for proliferation cell nuclear antigen and Ki-67 antigen Application to intra-operative frozen diagnosis. Pathol. Int. 45 108-115. 

PAP, peroxidase-antiperoxidase ABC, avidin-biotin conjugate APAAP, alkaline phosphatase antialkaline phosphatase B-SA, biotin-streptavidin PCNA, proiiferating cell nuclear antigen EPOS, enhanced polymer one-step staining (Dako) CARD, catalyzed reporter deposition HRP, horseradish peroxidase. 

Van der Loos CM, Naruko T, Becker AE. The use of enhanced polymer one-step staining reagents for immunoenzyme doublelabeling. Histochemical J. 1996)18 709. 

Rott T, Velkavrh D. Our experience with the enhanced polymer one-step staining in frozen sections. Acta Otolaryngol. 1997 (Suppl 527) 114. 

Because of these limitations, polymer-based immunohistochemical methods that do not rely on biotin have been introduced and are gaining popularity (5). These methods utilize a unique technology based on a polymer backbone to which multiple antibodies and enzyme molecules are conjugated. In the EPOS (Enhanced Polymer One Step) system, as many as 70 enzyme molecules and about 10 primary antibodies were conjugated to a dextran backbone. This allowed the entire immunohistochemical staining procedure, from primary antibody to enzyme, to be accomplished in a single step (6). On the other hand, one limitation of this method was its restriction to a select group of primary antibodies provided by the manufacturer, and not suitable for user-supplied primary antibodies. 

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