Placental protein 5 in gestational trophoblastic disease: Localization and circulating levels

With the use of an indirect immunoperoxidase technique (peroxidase-antiperoxidase) placental protein 5 (PP5) has been shown to be present in a high percentage of gestational trophoblastic tumors, especially the better differentiated ones. By sensitive radioimmunoassay, PP5 has further been found to be present in sera from patients with persistent gestational trophoblastic disease but not to the same frequency or extent as human chorionic gonadotropin. The only finding of clinical importance was the association in one case of high levels of PP5 and concurrent intravascular coagulation.