Two Step Polymer Immunohistoprobe Plus® is an extremely sensitive immunohistochemistry detection system. It is based on signal amplification by using a two-step polymer detection method. The primary antibody specific to an antigen on the tissue section is detected by an amplifier for primary antibody then followed by polymer detector. The antigen sites are then intensely visualized with an appropriate substrate/chromogen. Immunohistoprobe Plus® does not use avidin or biotin, which completely eliminated nonspecific staining from endogenous avidin-biotin activity. It is currently the most sensitive detection system for IHC application.