Reduced percentage of natural killer cells associated with impaired cytokine network in the secretory endometrium of infertile PCOS women

Objective: To evaluate lymphocyte subset distribution in the secretory endometrium from infertile patients with polycystic ovary syndrome (PCOS), and the expression of the cytokines known to play a role in determining the endometrial lymphocyte pattern. Design: Experimental clinical study. Setting: Outpatient clinic in a university hospital. Patient(s): Twenty-eight patients with PCOS (PCOS group) and 6 fertile patients (control group). Intervention(s): On days 22–26 of a spontaneous cycle, subjects underwent endometrial biopsies. MainOutcomesMeasure(s): In19of28patientswithPCOSand6controlswithalatesecretoryendometrium,the percentage and phenotype of lymphocyte subsets were analyzed by flow cytometry. In the late secretory endome- trium of 11 patients with PCOS and 3 controls, the expression of interleukins 15 and 18 and of chemokine ligand 10 was also analysed by polymerase chain reaction. Result(s): In patients with PCOS the percentage of CD56þ/CD16 and of CD56bright/CD16 cells was signifi- cantly lower (median [confidence interval]: 38% [31%–52.7%] vs. 63.7% [57.7%–69%] and 17.4% [8%–41.6%] vs. 52% [43%–60%], respectively), whereas the percentage of CD3þ was significantly higher (45% [33.3%– 64%] vs. 26.1% [21%–32%]) as compared with controls. Accordingly, polymerase chain reaction analysis revealed a significantly lower expression of interleukins 15 and 18 and of chemokine ligand 10 in patients with PCOS than in controls. Conclusion(s): Results demonstrated an abnormal percentage of endometrial lymphocyte subsets, associated with an impaired cytokine network in patients with PCOS. This could explain the poor reproductive potential in these patients. (Fertil SterilÒ 2010;94:2222–7. Ó2010 by American Society for Reproductive Medicine.) Key Words: Infertility, uterine natural killer cells, PCOS, secretory endometrium, IL-15, IL-18, CXCL1