How IHC works
There are multiple ways to perform immunohistochemistry, but the following components are often involved:
The protein target is commonly referred to as the antigen. An antigen is the protein or peptide to which the antibody has been raised. IHC locates the protein targets in the tissue with the primary antibody, and detects it with a variety of chemistries.
The primary antibody is an antibody that binds tightly to a specific protein target/antigen. Many antibodies are approved for use in the diagnosis of diseases such as lung cancer, breast cancer, cervical cancer, colorectal cancer, dermatological cancer, hematopathology cancer, prostate cancer and other solid tumors. Primary antibodies can be labeled directly with a marker, but for greater sensitivity they are often used with a secondary antibody.
The secondary antibody recognizes the primary antibody. Use of a secondary antibody can result in greater sensitivity since it is coupled with an enzyme that reacts with chromogens or fluorescent molecules, causing them to be deposited on the tissue. To learn more about the use of secondary antibodies in IHC, see the Educational Resources.