CD11c ⁺HLADR ⁺ dendritic cells are present in human ovarian follicular fluid, and their maturity correlates with serum estradiol levels in response to gonadotropins

Objective: To determine whether dendritic cells (DCs), innate immune cells that specialize in initiation and modulation of immune responses, are present in ovarian follicular fluid (FF) and whether their abundance and maturation state correlate with ovarian response to gonadotropins. Design: Observational study. Setting: IVF unit and laboratory for reproductive immunology. Patient(s): Patients undergoing IVF. Intervention(s): None. Main Outcome Measure(s): FF was collected from the first follicle aspirated in each patient, and cellular content was analyzed by flow cytometry. DCs were defined as CD45 ⁺CD11c ⁺HLADR ⁺-cells, and the intensity of HLADR expression indicated DC maturity. Result(s): The CD45 ⁺-hematopoietic cell compartment in FFs (n = 30) contained a significant fraction of CD11c ⁺HLADR ⁺ DCs (15.4% ± 2.9%). The mean fluorescence intensity (MFI) of HLADR expression, which reflects DC maturity, correlated positively with ovarian response to gondotropins, as determined by serum levels of E ₂ on the day of hCG administration (r = 0.38). Conclusion(s): DCs make up a significant fraction of hematopoietic cells in the FF. Furthermore, DC maturation correlates positively with the ovarian response to gonadotropins. It is therefore conceivable that DCs contribute to the sterile inflammatory process in the follicle that leads to ovulation.