The effects of peritoneal fluid from patients with advanced endometriosis on HLA-DR expression of monocytes

Na, Yong Jin; Park, Jong Hoon; Kwak, Jong Young; Lee, Kyu Sup

Abstract

OBJECTIVE
Endometriosis is a common gynecologic disorder characterized by the presence of endometrial tissue outside the uterine cavity. Many theories have been suggested to explain the mechanism for the development of this disease. Although no single theory can explain all cases of endometriosis, retrograde menstruation theory has gained the widest acceptance. But the discrepancy between the incidence of retrograde menstruation and prevalence of endometriosis suggests that additional factor(s) may determine susceptibility to endometriosis in the peritoneal cavity and the survival and implantation of endometrial cells seem to be related with immunologic factors. For evaluation of the immunologic factors, we investigated the effects of peritoneal fluid from patients with advanced endometriosis (EPF) on the HLA-DR expression of monocytes.
METHODS
EPF (n=20) and peritoneal fluid from the control group (CPF) (n=10) were collected prior to main laparoscopic operation. CPF were obtained from fertile women with various gynecologic problem other than endometriosis, such as dermoid cyst and carcinoma in situ of the uterine cervix. Peripheral blood mononuclear cells were collected by density-gradient centrifugation of whole blood over a peripheral blood mononuclear cell separation medium (Histopaque-1077), and THP-1 cells derived from a monocyte/macrophage cell line (Korean Cell Line Bank, Seoul, Korea) were cultured in RPMI-1640 medium. The expression of HLA-DR was evaluated by confocal microscopy, and the levels of IL-10, TGF-beta and VEGF were measured by standard enzyme-linked immunosorbent assay kits (R and D system).
RESULTS
Compared to CPF, the addition of 10% EPF (n=10) to culture medium significantly reduced the percentage of HLA-DR positive cells in cultures of a THP-1, monocytic cell line at 48 hours. The effect of EPF was dose-dependent, and similar effect was observed in the peripheral blood monocytes. An inverse correlation was found between the HLA-DR expression level and IL-10 concentration in EPF (r=-0.518; P=0.019) and in the supernatant of peripheral blood monocyte cultured in EPF (n=20) (r=-0.459; P=0.042). IL-neutralizing antibody significantly abrogated the effect of EPF on HLA-DR expression level.
CONCLUSION
These results suggest that HLA-DR expression level on monocytes is down-regulated by EPF, and that IL-10 may be one of the factors in EPF to modulate HLA-DR expression level.