Interleukin-17A and Thyroid Autoantibodies in Follicular Fluid and Their Relation to Ovarian Response

Interleukin-17A (IL-17) and thyroid autoimmunity have been linked to adverse reproductive outcomes, but their role in the ovarian follicular environment in assisted reproductive technology remains unclear.

To evaluate IL-17 and thyroglobulin autoantibody levels in follicular fluid (FF) of euthyroid women undergoing intracytoplasmic sperm injection-embryo transfer (ICSI-ET) and their association with ovarian response, fertilization, and embryological outcomes.

This prospective study included 87 euthyroid women undergoing ICSI. Ovarian response was classified as low, suboptimal, normal, or high based on the number of oocytes retrieved. FF samples were collected at oocyte retrieval, and IL-17 and thyroglobulin autoantibody levels were quantified using ELISA.

IL-17 levels were significantly higher in high responders compared to normal responders (p = 0.032) and positively correlated with the number of metaphase II oocytes and fertilized oocytes in this group (p = 0.047 and p = 0.046). In low responders, both IL-17 and thyroglobulin autoantibody levels were negatively correlated with the fertilization rate (p = 0.001 and p = 0.024). Neither IL-17 nor thyroglobulin antibody levels predicted clinical pregnancy in the whole cohort after adjusting for age.

Elevated IL-17 levels are associated with high ovarian response, whereas IL-17 and thyroglobulin autoantibodies may affect fertilization potential in women with low response.