Immunohistochemistry (IHC) relies on antigen-antibody reactions to detect specific proteins within tissues. Primary antibodies bind to target antigens, and secondary antibodies coupled with enzymes or fluorescent dyes amplify the signal. For example, a common IHC reaction involves the use of a primary antibody against a protein of interest, followed by a secondary antibody conjugated with horseradish peroxidase (HRP). The HRP then catalyzes a color-producing reaction, highlighting the location of the target protein.
