A Study On The Expression Of FasL On The Human Trophoblasts And The Apoptosis Index(AI) Of Lymphocytes In Decidua And Maternal Blood In Patients With Normal Pregnancy And Pregnancy Induced Hypertension (PIH)

Objective: To detect the expression of Fas ligand(FasL) on the human trophoblasts, determine the apoptosis index(AI) of lymphocytes in decidua and maternal blood in patients with normal pregnancy(NLP) and pregnancy induced hypertension(PIH), and futher study the mechanism of maternal-fetal immune tolerance and pathogenesis of PIH.Methods: Part I : 28 PIH patients and 22 NLP women in the third trimester were observed in this study. Immuno-histochemistry were used to investigate the expression of FasL on the human cytotrophoblasts, and highly precise color-image measure system for immuno-histochemisty was used for quantitative analysis. We analyzed AI of lymphocytes isolated form decidual tissues using flow cytometric method(FCM). Part II: 20 PIH women and 20 NLP women werestudied. We detect the AI of lymphocytes using FCM when lymphocytes were isolated from maternal blood mechanically.Results: FasL were expressed on the surface of cell membrane and in the cytoplasm of placental cytophoblasts in NLP and PIH. The strength and the scale ratio of FasL expression in PIH group, (90.087 ± 8.892) and (0.073 ± 0.026)%, were significantly lower than those of control group, (76.242±7.457) and (0.119± 0.019)%(p < 0.05). The quantity of FasL expression between NLP and slight PIH, between moderate and severe PIH, showed no difference(p > 0.05), but the expression of FasL in slight PIH were significantly higher than those in moderate and severe PIH(p< 0.01). The AI of lymphocytes isolated from decidua and peripheral blood in PIH, (1.103±0.506)% and (0.149 ± 0.106)% were significantly lower than those in NLP,( 1.774±0.430)% and (0.642±0.402)% (p<0.05).There was a significant correlation between AI of decidual lymphocytes and the value of FasL in trophoblasts. The coefficient were -0.4653 in NLP and -0.3863 in PIH. .There was a significant correlation between AIof decidual lymphocytes and that of maternal blood. The coefficient were 0.612 and 0.599 (p<0.05). The newboras wight and placental weight in patients with PIH [(3014.29±604.28)g, (566.61 ± 113.48)g respectively] were significantly decreased with NLP [(3340.91±423.60)g, (638.64±112.17)g respectively].Conclusion: Like many immune-privileged sites, the maternal specific lymphocytes apoptosis induced by FasL on the maternal-fetal interface might be one of the significant mechanisms of maternal-fetal immune tolerance. Abnormal expression of FasL on placental trophoblasts, which induced abnormal apoptosis of lymphocytes in decidua and destroyed the immune tolerance on the maternal-fetal, may be one of the important mechanisms of the etiology of PIH. We might understand the situation of maternal-fetal interfaces by determining AI of lymphocytes in maternal blood.