Summary. Certain strains of mice display an increased frequency of fetal resorption, but little is known about the effector mechanisms involved. We have examined the events associated with lipopolysaccharide (LPS)-induced fetal resorption in mice. Administration of 25 μg LPS on Day 12 of gestation resulted in the appearance of tumour necrosis factor-alpha (TNF-α) in the amniotic fluid and fetal resorption. Levels of LPS-induced TNF-α were reduced by 90% after pretreatment with the TNF-α-suppressing drug pentoxifylline (PXF). Treatment of pregnant mice during early gestation with 0·1 μg LPS resulted in fetoplacental resorption which was maximal when the LPS was given on Day 8. Resorption induced by 0·1 μg LPS on Day 8 of gestation was significantly reduced by pretreatment with PXF. Infiltration of asialo-GM1-positive cells was observed in the decidual–ectoplacental cone area of embryonic units from LPS-treated mice. In addition, treatment with anti-AGM1 antiserum prevented the LPS-induced resorption. Our results suggest that TNF-α and asialo-GM1-positive cells are involved in LPS-induced fetal resorption.

Keywords: abortion; lipopolysaccharide; TNF-α; natural killer cells; pentoxifylline; mouse