Function of Follicular Cytokines: Roles Played during Maturation, Development and Implantation of Embryo

A balance within the immune system is necessary for the proper development of ovarian follicles. Numerous cytokines were detected in follicular fluid, the role of which in reproductive physiology seems crucial. They influence the development and maturation of the follicle, ovulation, and corpus luteum formation, as well as embryo implantation and maintenance of pregnancy. The analysis of follicular fluid requires its collection by puncturing of the ovary, which is usually executed in connection with various gynaecological procedures. When interpreting such test results, clinical indications for a given procedure and the method of patient preparation should be taken into account. This review revealed the results of currently available studies on the concentration of pro-inflammatory cytokines in follicular fluid in various forms of infertility. Additionally, it presented cytokines, whose concentration has a significant impact on the size of ovarian follicles, their number, the effectiveness of in vitro fertilisation, development of the embryo, and chances of correct implantation. Despite the many recent publications, the knowledge of follicular fluid immunology in the context of reproductive pathology is superficial and further research is required to extensively understand the roles of individual cytokines in reproductive pathology. In the future, this knowledge may enable patients' individual qualifications to individual methods of infertility treatment, as well as the possible adjustment of the treatment regimen to the patient's immune profile.