Placental Expression of CD15 in Fetal Anemia From Hydrops Fetalis

CD15 expression has been used as a marker of endothelial immaturity in the placenta and is linked to the setting of antenatal hypoxia. If so, expression should be increased in fetal anemia, especially when severe enough to cause hydrops fetalis. This has not been previously reported and the current study tested this hypothesis.

The study group consisted of 10 cases of anemic hydrops in second to early third trimester of gestation and 10 controls matched for gestational age. The majority (70%) of hydrops cases were due to hemoglobin (Hb) Bart. Placentas underwent CD15 immunohistochemical staining and results were quantitatively assessed by counting 100 vessels in each case.

For the anemic group, the mean number of CD15+ vessels was 52.0% in the proximal vasculature and 91.3% in the distal vasculature. Values for controls were 32.9% and 42.2%, respectively. The CD15 expression in the distal vasculature was significantly higher in the anemic hydrops group (P < .001), but not significantly higher for the proximal vasculature (P = .14). In the control group, the number of CD15+ vessels decreased with increasing gestational age for both proximal and distal vasculatures. In contrast, in the anemic hydrops group, the number of CD15+vessels did not significantly change with gestational age, for both the proximal and distal vasculatures.

Placentas belonging to anemic hydrops cases demonstrate significantly increased expression of CD15 in the distal vasculature. CD15 expression in HF may be driven by hypoxia, reflecting an attempt by the placenta to compensate for this.