Immunohistochemistry techniques have been used since the 1940s, when AH Coons and colleagues published their landmark paper describing the identification of tissue antigens using a direct fluorescence protocol (Coons AH, Creech HJ, Jones RN (1941) Immunological properties of an antibody containing a fluorescent group. Proc Soc Exp Biol Med 47:200–202).

Immunohistochemistry enables the visualization (using light or confocal microscopy) of the tissue distribution of specific antigens (or epitopes). The process localizes protein targets of interest by applying specific monoclonal or polyclonal antibodies to tissue surfaces in a process called antibody incubation. In recent years, the protocol has been refined with the advent of avidin-biotin immunohistochemistry.

This procedure makes use of the high affinity that avidin (or streptavidin) has for biotin. Multiple binding sites on the molecules result in the amplification of the tissue signal which is useful when trying to detect low copy number antigens.

A collection of useful immunohistochemistry protocols and other methods are available in the protocols section of the website. Protocol optimization is crucial to obtaining successful and reproducible results; the troubleshooting section has some useful suggestions for improving immunohistochemistry results.

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