We have been reported the fragile immune response such as decreased abdominal NK cell chemotaxis in women with endometriosis. In this paper, we investigated the turbidity and cell concentration of peritoneal fluid, and NK cell chemotaxis and the percentages of HLA-G+ cells during menstrual cycle.

Participants included women with endometriosis (group E) and without endometriosis (group C) who underwent laparoscopic surgery in our department. Peritoneal fluid was obtained during the surgery. Turbidity was measured by spectrophotometer, the cell concentration was measured by Burker-Turk calculator. NK cell chemotaxis was measured by time-lapse photography. Percentages of HLA-G+ endometrial cells were examined by flow cytometry. These were compared between menstrual period and non-menstrual period. This study was approved by Kochi Medical School IRB, and informed consent was obtained before surgery.

A significant positive correlation was found between turbidity and cell concentration. In the menstrual period, no significant difference was observed between two groups in all measurement items. After menstruation, turbidity, cell concentration, and percentages of HLA-G+ endometrial cell was decreased in both groups, but these were significantly higher in group E. Furthermore, after menstruation, though the chemotaxis of group C was increased, but there appeared no significant changes in group E compared to that in menstrual period.

In women with endometriosis, cytotoxicity and chemotaxis to HLA-G+ endometrial cells are decreased; thus, fragile immune response continues even after menstruation. In conclusion, fragile immune response and repeated retrograde menstruation maybe a major factor for the progression of endometriosis.