Diagnosis:
Detection Methods for Immunohistochemistry
• The avidin-biotin peroxidase complex method, although highly sensitive, does cross-react with endogenous biotin. This reaction can be reduced by the use of avidin biotin block or a combination of egg white and skim milk powder.
• For routine diagnostic use, adoption of a polymer-linked, enzyme-labeled secondary antibody eliminates this problem and, by combining the secondary antibody and enzyme in the same step, speeds up the process.
• The three-dimensional branching structure of the dextran polymer may cause some steric effects with some antigens.
• The APAAP method utilizes the divalent nature of the secondary antibody to link the primary antibody to the APAAP complex; therefore, both the primary antibody and the anti-AP antibody should be of the same species.
• Chromogens, which can be used with permanent cover-slipping methods, are available and include nitroblue tetrazolium (NBT) and new fuchsin.
Taylor CR, Shi S-R, Barr NJ, Wu N: Techniques of immunohistochemistry: principles, pitfalls, and standardization.In Dabbs DJ (ed): Diagnostic Immunohistochemistry. New York: Churchill Livingstone, 2002, pp 3-44.
