Placental-type alkaline phosphatase in peritoneal fluid of women with endometriosis

Alkaline phosphatase (ALP) activities were studied in peritoneal fluid obtained from patients with untreated endometriosis and control women who had normal pelves. The patients (n = 18) had significantly higher total ALP (8.65 +/- 5.69 mU/mg, p less than 0.01) and thermostable ALP (0.28 +/- 0.23 mU/mg, p less than 0.05) than the controls (n = 7) (total ALP = 2.41 +/- 1.15; thermostable ALP = 0.09 +/- 0.04 mU/mg). The contents of the thermostable ALP in the total ALP were 4.5 +/- 2.4% for controls and 3.6 +/- 2.3% for patients. To define the biochemical characteristics of the thermostable ALP, the enzyme was partially purified from a mixture of peritoneal fluid from 16 patients. The partially purified, heated ALP (PFALP) responded to the various inhibitors, activators, and pH values tested in a significantly similar manner as a purified, heated human placental ALP did. Our data suggest that PFALP may be a placental-type (or Regan) ALP.