[Expression of leukemia inhibitory factor in chorionic villi of normal early pregnancy, threatened abortion and inevitable abortion]

To examine the expression of leukemia inhibitory factor (LIF) in chorionic villi of normal early pregnancy, threatened abortion and inevitable abortion, and to assess the effects of LIF on threatened abortion and inevitable abortion.

Expression of LIF in chorionic villi was examined using Western blot. Serum progesterone and human chorionic gonadotropin (hCG) levels were determined using radioimmunoassay. A streptavidin peroxidase conjugated semi-quantitative immunohistochemical assay was used to exam LIF protein expression.

The levels of progesterone and hCG in the normal early pregnancy and threatened abortion groups were (95 +/- 26) nmol/L and (75 +/- 14) kU/L, and (90 +/- 26) nmol/L and (68 +/- 13) kU/L, respectively. The differences were not significant (P > 0.05). The levels of progesterone and hCG in the inevitable group were significantly decreased to (36 +/- 17) nmol/L and (13 +/- 3) kU/L, respectively. The differences when compared to the other groups were statistically significant (P < 0.01). LIF protein expression was observed in all cases and located mainly in the cytoplasm of trophoblast cells. The expression of LIF in inevitable abortion group 0.30 +/- 0.02 was lower than that in other groups (P < 0.01). However, there was no significant difference in the expression of LIF between the normal early pregnancy group and threatened abortion group (P > 0.05).

LIF may play a role in the maintenance of normal pregnancy. Reduction of LIF expression in chorionic villi may induce the decrease of serum progesterone and hCG levels and, ultimately, cause inevitable abortion.