A novel pilot study of endometrial stromal cells and immune cell populations in sentinel uterine-draining lymph nodes during the menstrual cycle and in endometriosis.

Recent studies suggest that changes in certain uterine immune cell populations in endometrium of women with endometriosis are likely to precede changes at ectopic sites. This preliminary study is a first look into the function of uterine-draining lymph nodes (LNs) during the menstrual cycle and in the presence of endometriosis. Paraffin-embedded obturator LNs were obtained from women with (n = 7, mean age 44.3) and without (n = 9, mean age 38.4) endometriosis, who had undergone hysterectomy for cervical or ovarian cancer and in whom LN involvement was not detected. Immunohistochemical staining for endometrial stromal cells and a range of immune cell populations was performed. The CD10+ endometrial stromal cells were detected in uterine-draining LNs throughout the menstrual cycle with numbers peaking during menstruation. The inflammatory process of menstruation was also associated with increased numbers of CD3+, CD4+, Foxp3+, DC-Sign+, CD68+, CD20+, CD79+, and plasma cells. In endometriosis, CD10+ endometrial stromal cells were further increased in numbers, but CD3+, CD4+, DC-Lamp+, FoxP3+, and plasma cells were reduced. This study indicates that efficient immunological responses may be required to contain shed endometrial fragments within the draining uterine LNs thus preventing their further dissemination with establishment of ectopic lesions at distant sites.