Expression of human leukocyte antigen-G during normal placentation and in preeclamptic pregnancies

This study was undertaken to investigate the expression pattern of human leukocyte antigen-G (HLA-G) during normal placentation and determine whether altered expression of HLA-G is associated with severe preeclampsia.

We investigated HLA-G protein levels in first (n = 27), second (n = 7), and third trimester placentas (n = 10) from normal pregnancies, and determined HLA-G levels in term placentas from normal (n = 15) and severe preeclamptic pregnancies (n = 14) using real-time RT-PCR and western blot analysis.

In normal placentas, HLA-G protein expression reached a peak level at gestational weeks 6 and 7, then gradually decreased from week 8 to third trimester (p < 0.05). In preeclamptic placentas, both HLA-G mRNA and protein levels were decreased significantly in comparison with normal term placentas (p < 0.05).

HLA-G may contribute to placentation during early and mid-term pregnancy, and participate in maintaining gestation during term pregnancy. The reduced level of HLA-G may be associated with pathogenesis of preeclampsia.