[Expression of human leucocyte antigen G on human placenta and its gene polymorphism in relation to intrahepatic cholestasis of pregnancy].

OBJECTIVE

To investigate the expression of human leucocyte antigen G (HLA-G) on human placenta and its gene polymorphism in relation to intrahepatic cholestasis of pregnancy (ICP).

METHODS

Immunohistochemistry was utilized to detect the HLA-G protein expression on third trimester placenta of fifteen normal pregnant women (control group 1), fifteen ICP patients treated with dexamethasone (ICP group with dexamethasone treatment) and ten ICP patients treated without dexamethasone (ICP group without dexamethasone treatment). We used polymerase chain reaction with sequence-specific primer (PCR-SSP) method to detect the 14 bp deletion polymorphism in exon 8 of HLA-G gene of thirty normal pregnant women and their babies (control group 2), thirty ICP patients and their babies (ICP group).

RESULTS

(1) The positive expression of HLA-G on placenta extravillous cytotrophoblast and its mean optical density of ICP group without dexamethasone treatment 56 +/- 8 was significantly lower than those of normal control group 70 +/- 10 and ICP group with dexamethasone treatment 66 +/- 9 (P < 0.05). No significant differences were found between normal control group and ICP group with dexamethasone treatment (P > 0.05). (2) There were no statistical differences between the control group and the ICP group with regard to the allele and genotype of the 14 bp deletion polymorphism in exon 8 of HLA-G gene (P > 0.05).

CONCLUSIONS

The reduced expression of HLA-G on placenta in ICP patients may alter the maternal-fetal immune response and thus be involved in the pathogenesis of this disorder. Dexamethasone can upregulate the expression of HLA-G on placenta. The 14 bp deletion polymorphism in exon 8 of HLA-G gene might not have a significant influence on the development of ICP.