Excessive ovarian response is associated with increased expression of interleukin-2 in the periimplantation endometrium

ObjectiveTo evaluate and compare in vivo expression of T helper type 1 (Th1) cytokines in the peri-implantation endometrium of infertile patients between natural and stimulated cycles.DesignAn observational study.SettingA tertiary assisted reproduction center.Patient(s)Infertile patients.Intervention(s)Uterine flushings and endometrial biopsies were collected 7 days after LH surge in natural cycles or after hCG injection in stimulated cycles.Main Outcome Measure(s)T helper type 1 cytokines were determined by immunolocalization and by ELISA.Result(s)Natural cycles were classified as group A (n = 17), whereas stimulated cycles with peak serum E2 of ≤20,000 pmol/L (moderate responders) and with peak serum E2 of >20,000 pmol/L (excessive responders) were classified as group B (n = 32) and group C (n = 32), respectively. Higher serum E2 concentration was associated with increased expressions of interleukin (IL)-2 in the endometrium and uterine flushing. Group C demonstrated a statistically significantly higher IL-2 expression in endometrial biopsies by glandular and stromal immunostaining and by ELISA, compared with group A and group B. There was no difference in IL-2 concentration between group A and group B. Interferon-γ protein concentration was comparable for the three groups.Conclusion(s)Increased expression of IL-2 in the peri-implantation endometrium may account for the lower implantation rate in excessive responders.