Leukaemia inhibitory factor expression in human follicular fluid and ovarian cells

Leukaemia inhibitory factor (LIF) is a 43 kDa glycoprotein with aremarkable range of biological actions in different tissue systems. LIFimproves the rate of fertilization of mouse oocytes in vitro and up-regulates aromatase enzyme. We postulated that LIF may be an importantmodulator of ovarian function and may also improve embryo quality inhumans. Follicular fluid samples from patients undergoing in-vitrofertilization (IVF) and embryo transfer (n = 123), from women undergoingovarian stimulation (n = 4) and from women undergoing laparoscopy for tuballigation during their follicular phase (n = 3) were used. Follicular fluidLIF, oestradiol, and progesterone were measured and embryo quality wasassessed. Granulosa-lutein cells were cultured for 3 days in Ham'sF-12:Dulbecco's modified Eagle's medium (DMEM). Ovarian stromal cells,isolated by enzymatic dispersion of ovarian tissue, were also cultured inthe same medium. Following experimental treatments, LIF mRNA and proteinconcentrations were quantified. The concentration of LIF was 0.8 +/- 0.3(mean +/- SEM) pg/ml in pre-human chorionic gonadotrophin (HCG) follicularfluid samples and 13.0 +/- 1.1 pg/ml in post-HCG follicular fluid samples(P < 0.05). LIF levels were undetectable in three follicular fluidsamples obtained during unstimulated follicular phase. There was acorrelation between follicular fluid LIF and follicular fluid oestradiolconcentrations (r = 0.36; P = 0.0001) and the number of grade I embryos (r= 0.62; P = 0.01). LIF mRNA and the protein were expressed constitutivelybut in low amounts in the ovarian stromal cell cultures. The concentrationsof LIF mRNA as well as protein were increased by interleukin (IL)-1alphaand tumour necrosis factor alpha (TNF alpha) in a time- andconcentration-dependent manner. Purified granulosa-lutein cells expressedlow amounts of LIF mRNA and protein which were not significantly increasedby IL-1alpha or TNF alpha. Our findings suggest that HCG stimulates theexpression of LIF in follicular fluid. Both granulosa-lutein and ovarianstromal cells express the LIF mRNA and produce the protein. Modulation ofLIF in these cells may play an important role in the physiology ofovulation and early embryo development.