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Unmasking antigens for immunohistochemistry
1Edinburgh University Department of Veterinary Pathology, Easter Bush Veterinary Centre, Roslin, Midlothian, UK.
Insights
Formalin fixation and paraffin embedding are standard for tissue morphology but damage antigens for immunohistochemistry. Antigen retrieval techniques, including enzymatic, non-enzymatic, and heat-based methods, have revolutionized immunohistochemistry for diagnostic pathology.
Area of Science:
- Histopathology
- Immunohistochemistry
- Biochemical analysis
Background:
- Formalin fixation and paraffin embedding (FFPE) are standard for tissue preservation and morphological analysis.
- FFPE processing can alter antigen structure, hindering subsequent immunohistochemical (IHC) studies.
- Immunohistochemistry is a crucial diagnostic tool in pathology.
Purpose of the Study:
- To review the development of antigen retrieval techniques.
- To appraise current methods for antigen retrieval in immunohistochemistry.
- To highlight the impact of antigen retrieval on diagnostic pathology.
Main Methods:
- Review of enzymatic antigen retrieval methods.
- Review of non-enzymatic antigen retrieval methods.
- Review of heat-based antigen retrieval methods.
Main Results:
- Antigen retrieval techniques have significantly improved IHC sensitivity and specificity.
- Various methods exist, including enzymatic, non-enzymatic, and heat-based approaches.
- These techniques overcome limitations of FFPE for IHC.
Conclusions:
- Antigen retrieval is essential for effective immunohistochemistry after FFPE.
- The development of these techniques has transformed diagnostic pathology.
- Current methods offer diverse options for optimizing IHC staining.
Abstract:
Preservation of tissue by fixation in a formalin solution, followed by dehydration and paraffin-wax embedding remains the predominant method of preparation for microscopic analysis of morphology. Whilst this may be optimal for morphological assessment, this technique has major disadvantages for subsequent immunohistochemical study as a result of the structural alteration of antigens that occurs during the processing procedure. However, the introduction of a range of antigen unmasking procedures has revolutionised immunohistochemistry, establishing the technique as a powerful tool in diagnostic pathology. Here, the development of enzymatic, non-enzymatic and heat-based antigen retrieval techniques is reviewed, and the methods in use currently are appraised.