Macrophage expression in endometrium of women with and without endometriosis

Endometriosis is an inflammatory condition, characterized by the presence of endometrial-like tissue outside the uterus. The immune system provides a defence mechanism in response to foreign pathogens, and macrophages play important roles in this response. Activation of macrophages has been reported in peritoneal fluid and ectopic endometriotic lesions; however, controversy exists regarding the composition and function of macrophage populations in eutopic endometrium of women with and without endometriosis. This study aimed to quantify macrophages in eutopic endometrium of women with and without endometriosis, during the early, mid and late proliferative and menstrual phases of the cycle.

Paraffin-embedded endometrial curettage blocks were selected from pathology archives. Seventy-six specimens from women with and without endometriosis were analysed using standard immunohistochemical techniques with CD68-PGM1 (phosphoglucomutase 1) clone antibody. Macrophages were counted according to their morphology over several fields of view.

A significant increase in macrophage cell numbers was shown in eutopic endometrium in women with endometriosis (mean +/- SD, 182.7 +/- 72.9/mm(2)) during all stages of the proliferative phase compared with normal controls (101.6 +/- 53.4/mm(2); P < 0.001). Significant increase in macrophage density occurred in the control group during the mid-menstrual phase, Days 3-4 (P < 0.01), which was not observed in women with endometriosis.

This study further supports an association between immune changes in eutopic endometrium and presence of endometriosis. However, it remains uncertain if eutopic immune changes are primary or secondary occurrences.