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A simple technique for preservation of fixation-sensitive antigens in paraffin-embedded tissues
1Department of Pathology, Oregon Health Sciences University, Portland 97201.
Insights
A new zinc-based buffer fixative offers superior antigen preservation in paraffin-embedded tissues, matching frozen sections. This method combines excellent antigen survival with the convenience and morphology of traditional formalin fixation for immunohistochemistry.
Area of Science:
- Histopathology
- Immunohistochemistry
- Biochemistry
Background:
- Immunohistochemistry is crucial for tissue diagnosis and research.
- Frozen sections are the gold standard but have limitations.
- Paraffin-embedded tissues offer convenience but poor antigen preservation.
Purpose of the Study:
- To develop a new paraffin-embedding method for optimal antigen preservation.
- To compare a novel zinc-based fixative with traditional methods.
- To achieve both antigen survival and morphological quality.
Main Methods:
- Paraffin-embedded tissues were fixed using various methods, including a novel zinc buffer.
- Human lymphoid tissues and specific cell surface marker antibodies were used.
- Comparison of antigen preservation and morphological quality was performed.
Main Results:
- The zinc buffer fixative demonstrated antigen preservation comparable to frozen sections.
- Morphological preservation was similar to routine formalin-fixed sections.
- This new method closely combines antigen survival with convenience and morphology.
Conclusions:
- A simple zinc buffer fixative provides excellent antigen preservation in paraffin-embedded tissues.
- This technique overcomes limitations of traditional methods for immunohistochemistry.
- It offers a practical solution for combining diagnostic morphology with antigen integrity.
Abstract:
Immunohistochemistry is a powerful tool for tissue diagnosis and research. Although the frozen section has remained the gold standard for this important approach to evaluation of antigens in tissues, there is widespread acknowledgment of many limitations. Routine paraffin-embedded sections ware widely used for morphological examination of tissues but are not optimal for antigen preservation. In this study, paraffin-embedded tissues fixed with a simple buffer containing zinc as the primary fixative were compared with tissues fixed with routine formalin, zinc-formalin, paraformaldehyde, ethanol, a variety of commercial (non-formalin-containing) fixatives that have been recommended for reduced toxicity and improved antigen survival, and frozen sections. Human lymphoid tissues and a group of antibodies to antigens (CD1, CD4, CD7, CD8, CD19) usually preserved only in frozen tissue were used as a model system. Fixation in a simple solution of zinc acetate and zinc chloride in a Tris-Ca acetate buffer resulted in antigen preservation comparable to that in frozen sections with antibodies to these cell surface markers. Morphological preservation was comparable to formalin-fixed sections. The work presents a new method that represents the closest approach yet to a technique that combines optimal antigenic survival with the convenience and morphological preservation of traditional formalin-fixed tissue embedded in paraffin.