Effectiveness and potential mechanisms of intralipid in treating unexplained recurrent spontaneous abortion

Aim Abnormal natural killer (NK) cell activity has been suggested to be a high-risk factor associated with unexplained recurrent spontaneous abortion (URSA). Intralipid, like immunoglobulin, is able to lower the activity of NK cells, which has been reported to be useful for improving URSA outcomes in pregnancy. This study aimed to determine whether intralipid could be used as an alternative treatment to intravenous immunoglobulin (IVIG) which is expensive and has many side-effects. Methods A prospective, randomized clinical trial was conducted from December 2010 to December 2012. Eligible participants were matched and sorted randomly into the intralipid and the IVIG group. The primary outcome was the rate of successful pregnancy. In addition, comparisons of peripheral NK cell activities were accessed by flow cytometry. Moreover, the effects of intralipid on trophoblasts were investigated using a Matrigel assay with the JEG-3 cell line. Results Seventy-six patients in the intralipid group and 78 in the IVIG group completed the trial. There were no statistically significant differences in successful pregnancy rates between the two groups (92.1 vs 88.2 %, P = 0.415). The reduced NK cell concentrations revealed the cytotoxic effects of the treatments in both groups. The invasive ability of JEG-3 cells was inhibited during co-culture with patient PBMCs. However, the inhibitory effect could be alleviated if the patient PBMCs were stimulated with intralipid. Conclusions Intralipid can be used as an alternative treatment to IVIG for URSA, and its potential mechanism of action may occur by regulating NK cell function and promoting trophoblast invasion.