Immunopathology of alkaline phosphatase isozymes in seminoma.

An immunohistopathological study using monoclonal antibodies for alkaline phosphatases demonstrated placental alkaline phosphatase (PLAP)-like substance in the tumor cells of 11 pure seminomas, 1 seminoma with embryonal carcinoma and 1 seminoma metastasis. Liver alkaline phosphatase (LAP) could also be demonstrated in all seminomas but a third intestinal alkaline phosphatase (IAP) was not demonstrable in any tumor. The PLAP-like substance and LAP had considerable enzyme activities. This provides two tumor markers of seminomas detectable in histopathological specimens.