Human leukocyte antigen expression by peritoneal macrophages from women with pelvic endometriosis is depressed but coordinated with costimulatory molecule expression.

OBJECTIVE: To investigate the macrophage response in endometriosis, we determined expression of human leukocyte antigen (HLA)-ABC, HLA-DR, and their costimulatory molecules by peritoneal fluid (PF) macrophages. DESIGN: Case-control study of immunologic markers. SETTING: University hospital. PATIENT(S): We compared 38 Japanese women with endometriosis with 59 control subjects who were given other laparoscopic diagnoses. INTERVENTION(S): Venipuncture and laparoscopic peritoneal fluid collection. MAIN OUTCOME MEASURE(S): Expression of HLA-ABC, HLA-DR, CD54, CD40, CD58, CD80, and CD86 by peripheral blood (PB) monocytes and PF macrophages was quantitated as mean fluorescence intensities by flow cytometry. Expression of each marker on PF macrophages was divided by that on PB monocytes as an index of macrophage activation (macrophage activation ratio). RESULT(S): In women with endometriosis, PF macrophages showed significant positive correlations between expression of HLA-ABC and other costimulatory molecules and also between HLA-DR and their costimulatory molecules. However, expression of HLA-ABC and DR by PF macrophages, and also their activation ratios, were significantly lower than in controls. CONCLUSION(S): Coordination with costimulatory molecules but relatively low expression of HLA-ABC and HLA-DR indicates a positive but limited immune response (antigen presentation) to events in the peritoneal cavity in women with endometriosis. This may induce immune tolerance to implanted or metaplastic endometrial tissue.