Prostatic acid phosphatase

Serum marker PAP was used to monitor and assess progression of prostate cancer until the introduction of prostate specific antigen (PSA), which has now largely displaced it. Subsequent work, suggested that it has a role in prognosticating intermediate and high-risk prostate cancer, and led to renewed interest in it as a biomarker. Immunohistochemistry PAP immunohistochemical staining is often used with PSA (staining), by pathologists, to help distinguish poorly differentiated carcinomas. For example, poorly differentiated prostate adenocarcinoma (prostate cancer) and urothelial carcinoma (bladder cancer) may appear similar under the microscope, but PAP and PSA staining can help differentiate them; prostate adenocarcinoma often stains with PSA and/or PAP, while urothelial carcinoma does not. ==HIV==

PAP may play an important role in the transmission of HIV. Researchers at the University of Ulm in Germany found that PAP forms fibers made of amyloid. They called the fibers semen-derived enhancer of virus infection (SEVI) and showed that they capture HIV virions promoting their attachment to target cells. The association of PAP with HIV may increase the ability of the virus to infect human cells "by several orders of magnitude." PAP may be a future target of efforts to combat the spread of HIV infection. ==Pain suppression==

A study at the University of North Carolina and University of Helsinki suggested that PAP could have potent antinociceptive, antihyperalgesic, and antiallodynic effects that last longer than morphine. One dose of PAP lasted for up to three days, much longer than the five hours gained with a single dose of morphine. When in distress, nerve cells release a chemical known as adenosine triphosphate (ATP) which in turn invokes a painful sensation. ATP is broken down into AMP (adenosine monophosphate), which PAP converts into adenosine, a molecule known to suppress pain. ==History==

PAP was the first useful serum tumour marker and emerged in the 1940s and 1950s. ==See also==