ABSTRACT
Immunohistochemistry (IHC) is the process of localizing proteins in tissue section using monoclonal antibodies directed against specific antigens and visualizing the antibody–antigen reaction by one-step or two-step enzymatic reaction. IHC plays an important role in diagnostic hematopathology. The availability of monoclonal or polyclonal antibodies, automation, and protocols for antigen retrieval designed for formali-fixed, paraffin-embedded tissues made the IHC techniques a common practice in everyday diagnostic surgical pathology. A colorimetric reaction of the substrate identifies the presence of any given antigen under the microscope with its correlative morphologic parameters. Identification of numerous targets in formalin-fixed, paraffin-embedded tissues requires the antigen retrieval process that involves exposing the tissue sections to microwave ovengenerated high temperature. Depending on the location and distribution of the antigens, the color reaction may be visible in the nucleus, cytoplasm, cytoplasmic membrane, Golgi area, and/or nucleolus.
