Maternal soluble PD-1 levels are significantly increased in women with preeclampsia

Programmed cell death-1 (PD-1) and its ligand (PD-L1) have emerged as key players in regulating immune tolerance. Preeclampsia is associated with maladaptation of immune tolerance during pregnancy. This study aimed to determine if maternal soluble PD-1 (sPD-1) and soluble PD-L1 (sPD-L1) levels are altered in preeclampsia.

Maternal sPD-1 and sPD-L1 levels were measured by ELISA in 172 pregnant women (86 normotensive and 86 preeclampsia). The differences in sPD-1 and sPD-L1 levels between normotensive and preeclamptic pregnant women, <34 vs >34 weeks, and fetal gender differences were assessed. Data were analyzed by unpaired t test or chi-square. A probability level of <.05 was considered statistically significant.

Maternal sPD-1 levels were significantly higher in preeclamptic than in normotensive pregnant women, 6262 ± 1860 vs 1134 ± 349 pg/mL, P < .01. sPD-1 levels were not statistically different between <34 and >34 weeks of gestation in both normotensive and preeclamptic groups. sPD-1 levels were relatively higher in mothers with female fetus than with male fetus in the preeclamptic group: 8104 ± 3054 vs 3802 ± 2177 pg/mL, but relatively lower in mothers with female fetus than with male fetus in the normotensive group: 425 ± 134 vs 625 ± 182 pg/mL. Maternal sPD-L1 levels were relatively higher in preeclamptic than in normotensive pregnant women: 143 ± 52 vs 69 ± 13 pg/mL.

Aberrant sPD-1/sPD-L1 signaling is present in preeclampsia. Whether increased maternal sPD-1 and sPD-L1 levels were associated with fetal gender difference or immune tolerance dissimilarity during pregnancy in women with preeclampsia warrants further investigation.