Serum and peritoneal evaluation of vitamin D-binding protein in women with endometriosis

Introduction: Vitamin D-binding protein (also called DBP or Gc-globulin) is recognized as a multifunctional protein involved in the actin scavenger system, the transport of vitamin D sterols, and the modulation of immune and inflammatory responses. This study evaluated total serum and peritoneal concentrations of vitamin D-binding protein in women with endometriosis, known as an inflammation associated disease. Materials/Methods: The total concentration of DBP was measured with an enzyme-linked immunosorbent assay (ELISA) using a polyclonal antibody raised in a goat immunized with human DBP. Serum and peritoneal fluid were collected from women with endometriosis (n=26) and from patients with benign gynecological conditions serving as a control group (n=17). Results: In general, the vitamin D-binding protein concentration was higher in serum than in peritoneal fluid. Women with endometriosis had higher serum but lower peritoneal levels of DBP compared with the control group; however, no significance was noted. When the endometriosis group was divided with regard to severity, an insignificantly higher serum level of DBP was observed in advanced endometriosis compared with the mild form of the disease, whereas the peritoneal concentration was not dependent on disease severity. Conclusions: It is concluded that serum and peritoneal DBP concentrations are not affected in women with endometriosis; however, based on the latest published data, it is possible that both the serum and peritoneal concentrations of vitamin D-binding protein may be dependent on Gc genotype, which results in differential modulation of monocyte/macrophage activity.