The effects of the antiprogesterone RU486 (Mifepristone) on an endometrial secretory glycan: An immunocytochemical study

Objective: To examine the effects of progesterone (P) receptor blockade by RU486 (Mifepristone; Roussel-Uclaf, Paris, France) on a secretory endometrial glycan recognized by monoclonal antibody D9B1. Design: Retrospective comparison of endometrial biopsies from treated and untreated women from 2 to 8 days after the luteinizing peak (LH) peak. Setting: Infertility clinic, Jessop Hospital for Women, Sheffield. Patients: Twenty-two normal fertile women received the RU486. A control group of 44 normal fertile women were also assessed. Interventions: RU486 was administered to 22 normal women during the first half of the luteal phase and an endometrial biopsy examined 3 days later. Main Outcome Measures: Immunohistochemistry was used to assess the production and secretion of the D9B1 epitope. Results: When the drug was given 2 days after the LH peak, it prevented appearance of the epitope. When RU486 was administered 5 days after the LH peak, epitope already present in gland cells was subsequently secreted. Conclusions: These data suggest that production of the sialo-oligosaccharide is P-dependent, but secretion through established intracellular pathways is P-independent.