Association between decreased plasma levels of soluble human leukocyte antigen-G and severe pre-eclampsia

The aim of this study was to investigate the levels of different isoforms of soluble human leukocyte antigen-G (sHLA-G) in maternal plasma during early and late pregnancy, and to investigate the expression of sHLA-G isoforms in women with early or late-onset severe preeclampsia.

This prospective, nested, case-control study was performed in 24 early-onset severe preeclamptic, 34 late-onset severe preeclamptic, and 74 uncomplicated pregnant women. Plasma levels of sHLA-G1/5 were measured using ELISA.

Plasma sHLA-G1 levels in women with late-onset severe preeclampsia were markedly lower compared with normal controls (median: 0 vs. 1.22 ng/mL) at the first trimester, and plasma sHLA-G1 levels in women with early-onset severe preeclampsia were markedly lower compared with normal controls at the second (median: 0 vs. 1.24 ng/mL) and third (median: 0 vs. 1.34 ng/mL) trimesters. There was no difference between the late-onset and early-onset groups at three trimesters. As for sHLA-G5, there was no difference in concentrations among the three groups at any time point. However, compared with controls, more women with early- or late-onset severe preeclampsia had undetectable sHLA-G5 levels in the first (71.4% and 76.2% vs. 14.1%), second (75.0% and 73.3% vs. 19.0%), and third (100.0% and 70.4% vs. 14.8%, respectively) trimester (all P<0.05). sHLA-G1 levels in the first (odds ratio [OR]=0.254, 95% confidence interval [CI]=0.109-0.591, P=0.010), second (OR=0.315, 95% CI=0.158-0.627, P=0.001), and third (OR=0.170, 95% CI=0.054-0.533, P=0.002) trimester was a risk factor for severe preeclampsia.

Severe preeclampsia was associated with low/undetectable maternal plasma levels of sHLA-G. Low sHLA-G1 levels might be a risk marker for severe preeclampsia.