Chromogens Used With Alkaline Phosphatase (AP)

Need multiple seats for your university or lab? Get a quote
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)
Chromogens Used With Alkaline Phosphatase (AP)

Fast red TR and fast blue BB (red and blue) produce a bright red or blue end product but require aqueous mounting media since both are soluble in alcohol. An alternative to fast red TR and fast blue BB is new fuchsin (red) which is insoluble in alcohol and solvents.
Nitroblue tetrazolium (NBT) produces a blue-purple color reaction. NBT is nonsoluble so slides can be coverslipped with permanent mounting media.
Additional substrates used in alkaline phosphatase staining methods include naphthol AS-BI phosphate, naphthol AS-TR phosphate, and 5-bromo-4-chloro-3-indoxyl phosphate (BCIP).
It's important to remember that alkaline phosphatase is sensitive to heat and light, which can lead to staining inconsistency.
The image displays Varicella zoster in a section of skin, demonstrated with an alkaline phosphatase detection system and fast red chromogen.

Image provided by Jim Burchette, HT(ASCP)