Problems in Antigen Retrieval

This new definition of immunocytochemistry derives from advances in antibodylabeling methods in recent years. These advances resulted from specific needs in animal research. Initially, formalin-fixed paraffin sections were used for immuno-histochemistry however, results were inconsistent. In most cases, the antibody did not label anything or it labeled too many cells and was dubbed over fixed. This problem led to the development of the epitope retrieval or antigen retrieval methods, where sections of tissue are treated with heat in buffers before antibody incubations. Unfortunately, epitope retrieval methods can be unique from antibody to antibody and also, for the same antibody, from tissue to tissue. Epitope retrieval is complicated and best avoided. For animal research, a simple method was then developed where tissue was fixed in paraformaldehyde and not formalin or alcohol and subsequently frozen sections were cut on a cryostat. This eliminated the steps of dehydration, embedding in paraffin, rehydration after sectioning, and epitope retrieval before antibody incubation. This was a major breakthrough. 

---