Tissue sectioning epitope/antigen retrieval processing

Performing immunohistochemistry on these rehydrated paraffin sections frequently leads to poor results. In contrast, the same antibodies on paraformaldehyde-fixed and cryostat sections will give good results. The issue with formalin-fixed and paraffin-embedded tissue is that the exposure to formalin and dehydration alters the epitopes in the tissue. As a result, formalin-fixed and paraffin-embedded tissues need additional processing methods, known as epitope retrieval or antigen retrieval. Done before immunohistochemistry, epitope retrieval involves heating the sections in buffer with either an acid or base to allow the antibody to recognize the epitope. Also, the exact process of epitope retrieval can be different for individual antibodies. There are numerous papers and books on epitope retrieval and how to apply the method. 

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