[Placental alkaline phosphatase as a marker of malignant neoplasms]

Activity of placental alkaline phosphatase (PAP) was studied in blood serum of 53 healthy persons and of 72 oncologic patients, using solid-phase immunoenzymatic analysis with polyclonal antibodies towards PAP. The enzyme was detected both in blood serum of healthy persons and of oncologic patients. The blood serum under study was preheated at 65 degrees in order to inactivate the intestinal phosphatase--the only isoenzyme cross-reacting with antibodies to thermostable PAP. This controlled heating treatment decreased distinctly the possibility of pseudo-positive reactions. The limiting values of the PAP activity were about 0.15 un/L in blood sera of healthy persons. Higher values were considered as an evidence of pathological state. After screening analysis of blood sera from patients with various forms of malignant tumors the PAP activity above 0.15 un/L was observed in 20% of the patients; the enzymatic activity exceeded these values in 54% of patients with ovary carcinoma. The data obtained suggest that the procedure developed as an adequate means for estimation of thermostable PAP isoenzymes as well as that the rate of PAP activity might serve as marker of malignancy in ovary and testis carcinomas independently on level of total activity of alkaline phosphatase.