Follicular fluid expression of alpha-defensins and their role in ovulation

Defensins are cytotoxic peptides and have a well-defined role in host defense. Human alpha defensins 1-3 (HNP1-3) are primarily produced by peripheral neutrophils and constitute about 50% of the azurphil granule protein. Studies have suggested that peripheral neutrophils and the resident neutrophils in the ovary enhance the release of IL-8 and TNF-alpha that play a role in ovulation and influence fertilisation rate and IVF outcome. The production of HNP1-3 by follicular fluid and its role in ovulation has never studied. The aim of this study was to demonstrate the presence of HNP1-3 in follicular fluid and to ascertain its correlation with fertilisation rate and IVF outcome.

Women attending the Reproductive Medicine Unit at Liverpool Women's Hospital UK, for IVF treatment were invited to participate in the study. Sixty-three patients were recruited for the study and underwent controlled ovarian stimulation and oocyte retrieval according to the unit's protocol. Fluid from the first follicle only was collected to minimise blood contamination of the sample and HNP1-3 was estimated using ELISA technique.

HNP1-3 was detected in follicular fluid samples. The concentration did not correlate with the fertilisation rate (r=0.01). The concentrations were also not significantly different in the women who did or did not become pregnant following treatment. Subgroup analysis showed that women with endometriosis were not more likely to have higher levels of the HNP1-3 when compared with controls (male factor infertility group).

This is the first study to show the expression of HNP1-3 in follicular fluid. HNP1-3 concentrations did not correlate with fertilisation rate or IVF outcome. It did not show an increased expression of HNP1-3 in fluid collected from women with endometriosis suggesting that inflammatory processes associated with endometriosis do not influence HNP1-3 concentration in the follicular fluid. Further studies to evaluate the correlation between HNP1-3 and IL-8 and TNF-alpha may clarify the role of defensins in ovulation.