The page below is a sample from the LabCE course Immunohistochemistry (IHC) Basics in Histology. Access the complete course and earn ASCLS P.A.C.E.-approved continuing education credits by subscribing online.

Learn more about Immunohistochemistry (IHC) Basics in Histology (online CE course) »
How to Subscribe
Histology CE Package$65 Add to cart
Individual course$20 Add to cart


Substrates are detection systems that attach enzyme labels to the primary or secondary antibodies to visualize the localized antibody-antigen binding in tissue section. The enzymes are proteins that are used in IHC to convert a colorless reagent into a colored product (chromogen) that marks the site of antibody-antigen complex.
Commonly used enzyme labels for IHC procedures include:
  • Horseradish peroxidase (HRP)
  • Alkaline phosphatase (AP)
Others enzyme labels are ß-galactosidase and glucose oxidase.