Objective: Macrophages play a key role in implantation, placentation and parturition. Yet, whether or not the number of macrophages at the fetomaternal interface (basal plate of the placenta and placental bed) is altered in women with preeclampsia is the subject of controversy. The purpose of this study was to compare the immunoreactivity and distribution patterns of CD14 and CD68 positive macrophages in both the basal plate and placental bed from preeclamptic and non-preeclamptic pregnancies.
Methods: A cross-sectional study was conducted. Paraffin embedded sections of placental tissues and placental bed biopsies were obtained from patients with early onset preeclampsia (n=10) and from those with preterm labor/delivery (n=10) without preeclampsia matched for gestational age. Double immunohistochemistry using antibodies to CD14 and CD68 was performed, and the density of double or single positive cells in the basal plate and placental bed was evaluated. Non-parametric statistics were used for analysis.
Results: 1) A unique subset of CD14-/CD68+ cells was identified. The cells in question were present at a higher level in the decidua than in the myometrial segment of the placental bed (p<0.01); 2) The density and proportion of CD14+/CD68+ cells (double positive cells) were significantly higher in the myometrial segment than in the basal plate (p=0.0003); and 3) There were no significant differences in the density and patterns of immunopositive macrophages in the basal plate, the decidua, and the myometrium between women with preeclampsia and those with preterm labor/delivery (p>0.05).
Conclusion: The macrophages at the fetomaternal interface can be dichotomized by CD14 and CD68 immunoreactivity. A gradient of CD14+/CD68+ macrophages was demonstrated between the superficial myometrium and the basal plate regardless of the etiology of preterm birth (preeclampsia or spontaneous preterm labor). The biological function of single positive (CD14-/CD68+) and double positive (CD14+/CD68+) macrophages at the fetomaternal interface remains to be established. The overall findings also suggest that the discrepancies in the literature are due to the varying markers used to detect macrophages and in the anatomical plane of the fetomaternal junction analyzed.