Immunohistochemistry (IHC) is a laboratory technique that uses antibodies to detect antigens in a tissue sample. It is a powerful tool used by pathologists to look for signs of disease in a tissue sample. IHC is the most common type of immunostaining, which involves using antibodies and special markers to “label” parts of a tissue sample so they’re easier for pathologists to identify. The word “immunohistochemistry” provides clues about what’s involved: “immuno” means relating to your immune system, and “histo” refers to tissue.

IHC is used in a research context to study normal tissue and organ development, pathological processes, wound healing, cell death and repair, and many other fields. It is also used in drug development to test drug efficacy by detecting either the activity or the up- or down-regulation of disease markers in the target tissues and elsewhere.

The process of IHC involves incubating thin sections of tissues with an appropriate antibody, and the site of antibody binding is visualized under an ordinary or fluorescent microscope by a marker such as fluorescent dye, enzyme, radioactive element, or colloidal gold, which is directly linked to the primary antibody or to an appropriate secondary antibody. There are two main types of IHC:

• Chromogenic immunohistochemistry (CIH), wherein an antibody is conjugated to an enzyme, such as peroxidase, that can catalyze a color-producing reaction.
• Immunofluorescence, where the antibody is tagged to a fluorophore, such as fluorescein or rhodamine.

IHC is particularly useful in diagnosing certain types of cancer, providing the care team with a wealth of information about the disease to help determine treatment. It helps distinguish between different types and subtypes of a disease by identifying specific molecules within cells, known as markers. Markers are identified using antibodies, a type of protein that locates and binds with antigens (which are the markers found on cells) .

In summary, IHC is a laboratory technique that uses antibodies to detect antigens in a tissue sample. It is a powerful tool used by pathologists to look for signs of disease in a tissue sample and is used in a research context to study normal tissue and organ development, pathological processes, wound healing, cell death and repair, and many other fields. There are two main types of IHC: chromogenic immunohistochemistry and immunofluorescence. IHC is particularly useful in diagnosing certain types of cancer, providing the care team with a wealth of information about the dise...