Soluble Fas concentrations in the follicular fluid and oocyte-cumulus complex culture medium from women undergoing in vitro fertilization: association with oocyte maturity, fertilization, and embryo quality.

OBJECTIVE: Because soluble Fas (sFas) inhibits Fas-mediated apoptosis by preventing death signal transduction, we determined sFas concentrations in the follicular fluid (FF) and oocyte-cumulus complex culture medium (CM) from women undergoing in vitro fertilization (IVF) in order to associate its concentrations with oocyte maturity, fertilization, and embryo quality.

METHODS: We studied 82 follicles from 11 healthy women (mean age, 35.4 +/- 3.8 years) using a long protocol for IVF treatment. Individual FF and matched CM samples were immediately centrifuged at 4C and sFas concentrations were determined by sandwich enzyme-linked immunosorbent assays.

RESULTS: sFas concentrations were significantly higher in FF than in CM (P <.0001) and when oocytes were mature rather than immature (P <.002). Of 70 mature and 12 immature oocytes, 56 (80%) and two (16.6%), respectively, were fertilized. sFas concentrations in CM were significantly lower when mature oocytes were fertilized versus nonfertilized (P <.005). sFas concentrations in FF and CM were significantly related in an inverse manner to embryo quality (P = .004 and P = .0002, respectively).

CONCLUSION: FF and CM from women undergoing IVF contain sFas. The latter has anti-apoptotic properties and levels are higher: in FF when oocytes are mature and in CM when oocytes are nonfertilized. Furthermore, FF and CM sFas concentrations are negatively correlated with embryo quality.