The process of implantation involves two main components, a healthy embryo with the potential to implant and a receptive endometrium with the potential to enable implantation. Any abnormality associated with the embryo, the endometrium or the immune system will result in implantation failure. The factors which mainly disrupt the implantation include uterine fibroids, endometrial polyps, hydrosalpinx, thrombophilia in appropriate immunoregulatory function.
The infusion of 20% intralipid solution resulted in almost 50% successful outcome in women with repeated implantation failure who had an elevated TH1 cytokine response.
Intralipid infusion was administered once between 4-9 days of ovarian stimulation and again within 7 days of positive pregnancy test. In all cases the TH1 : TH2 activity ratio decreased significantly following treatment with intralipid. Intralipid is a fat imulsion that supresses abnormal NK cytoloxic activity in peripheral NK cells in women with recurrent IVF failure. Infusion of 2-4ml of 20% intralipid solution diluted in (100-250ml) of saline is sufficient to supress NK cells activity.
The mechanism of intralipid modulation is unclear, though it has been hypothesized that fatty acids in the emulsion serve as ligands to activate peroxisome proliferator-activcated receptors that decrease the NK cytotoxic activity leading the enhancement of implantation and maintainance of pregnancy.