Vitamin D binding protein in endometriosis.

OBJECTIVE: Two-dimensional gel electrophoresis is a powerful method for identifying post-translationally modified molecules in biological fluids. We examined the presence and expression of vitamin D binding protein (DBP) in the peritoneal fluid (PF) and plasma (PL) of women with endometriosis. METHODS: PL and PF samples were obtained from 36 women with untreated mild endometriosis (revised classification of the American Fertility Society [rAFS] stage I-II), 52 women with untreated severe endometriosis (rAFS stage III-IV), 17 women with endometriosis treated with the oral contraceptive (OC), and 40 controls (infertility, n = 23; tubal sterilization, n = 12; pelvic pain, n = 5). PF and PL samples were analyzed by quantitative, high-resolution 2-dimensional gel electrophoresis. RESULTS: The expression of one DBP isoform (DBPE) in the PF of patients with untreated endometriosis was significantly lower than in the control group (P <.05). The levels of PF DBPE in patients with endometriosis using OC were significantly higher than in women with untreated endometriosis (P <.05). No significant difference was observed in PL DBPE expression between women with and without endometriosis, while it was significantly increased in patients with endometriosis using OC (P <.05). DBP expression was not correlated with the stage of endometriosis (rAFS classification) or the phase of the menstrual cycle. CONCLUSION: The decreased level of DBPE in the PF but not in PL of women with untreated endometriosis suggests that this molecule may be relevant in the pathogenesis of this disease.