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General Epitope/Antigen Unmasking

Unmasking of the antigens from the effects of fixation is important for optimal staining. With aldehyde fixation, extended fixation times may damage antigens from the induction of molecular cross-links in proteins that can make it more difficult for the antibody to bind to its target. This is referred to as "antigen masking."

The term unmasking is identified under several names such as epitope retrieval, antigen retrieval (AR), antigen unmasking, and others that are usually trade names for companies that prepare retrieval reagents.
There are two main types of epitope retrieval:
  • Heat-induced epitope retrieval (HIER)
  • Enzyme-induced epitope retrieval (EIER)