Background: The aim of the study was to determine the presence of interleukin (IL)-12, IL-15, IL-18 and p40 subunit of IL-12/IL-23 in follicular fluid from spontaneous cycles and the relation between the concentration of selected cytokines and IVF-embryo transfer outcome.
Methods: IVF-embryo transfer and enzyme immunoassay (EIA) (R&D Systems, Minneapolis, MN, USA and MBL, Nagoya, Japan) were used.
Results: Follicular fluid of women included in the IVF-embryo transfer procedure contained common p40 subunit of IL-12/IL-23 (median 70.1 pg/ml), IL-15 (median 1.3 pg/ml) and IL-18 (median 38.2 pg/ml). There was a significant negative correlation between follicular fluid concentrations of IL-15 and IL-18 (R=-0.392, P=0.003). Significantly higher concentrations of common p40 subunit of IL-12/IL-23 (median 79.8 pg/ml) were found in the follicular fluid taken from follicles containing oocytes, when compared with those without an oocyte (median 44.5 pg/ml, P=0.006). Patients who achieved clinical pregnancy had significantly decreased concentration of IL-15 (median 0.8 pg/ml) compared with patients without successful IVF-embryo transfer outcome (median 1.4 pg/ml, P=0.047).
Conclusion: Follicular fluid collected from spontaneous cycles contains detectable levels of p40 subunit of IL-12/IL-23, IL-15 and IL-18. Increased concentrations of p40 subunit of IL-12/IL-23 in follicles containing oocytes suggest an important role of this cytokine in reproduction. Possible negative value of IL-15 as a predictor of IVF-embryo transfer success remains to be determined.