Natural killer cells and telomerase in the endometrium of patients with endometriosis

Background: Although endometriosis is a common cause of pelvic pain and infertility, the pathogenesis of the disease remains poorly understood. Several theories have been proposed to explain the mechanisms involved in the development of this disease, including the role of the immunological system. Objectives: To evaluate the percentage of endometrial natural killer (eNK) cells and telomerase expression in the endometrium of patients with and without endometriosis. Materials and methods: Endometrium samples were obtained during the mid-secretory phase from two groups of women: 12 women with endometriosis diagnosed by laparoscopy and confirmed by histological evaluation of the lesion, and 13 fertile women (control group) who underwent tubal sterilization at the same institution and in whom no signs of endometriosis were detected at surgery. Specific antibodies were used for the immunohistochemical assessment of eNK and telomerase. Results: eNK cells were significantly higher in the group of women without endometriosis (p<0.0001); however, telomerase expression in the endometrium was similar in the two study groups. Conclusions: Significantly fewer eNK cells were observed in the endometrium of women with endometriosis; however, there was no difference in telomerase expression. The finding of fewer eNK cells supports the hypothesis of a deficiency in the immune system facilitating the implantation of endometriotic tissue or interfering with implantation after fertilization.