Gestational Dynamics of Hofbauer Cells in the Human Placenta: Distribution, Morphology, and Immunophenotype.

Abstract

Background: Hofbauer cells (HBCs) are the only immunocompetent cells within the stroma of chorionic villi and play a key role in immune regulation and placental development throughout gestation. Their phenotype, abundance, and proliferative activity change in accordance with the needs of the fetoplacental unit.

Methods: Thirty healthy human placentas across all three trimesters were analyzed. Samples were processed using standard histological protocols and immunohistochemically stained with CD45, CD68, CD86, and Ki-67 markers. Morphometric analysis was performed to determine the following parameters: percentage of HBCs, numerical areal density, and proliferative index.

Results: HBCs were immunoreactive for CD45 and CD68, while CD86 immunoreactivity was not observed in any trimester. The proportion of HBCs was highest in the second trimester and lowest in the third. Numerical areal density was highest in the second trimester (22.21 ± 3.86) and lowest in the first (8.27 ± 4.18). The proliferative index was highest in the first trimester (82.45 ± 10.19%), decreased significantly in the second, and was completely absent in the third trimester.

Conclusions: During physiological placental development, Hofbauer cells maintain a predominantly non-M1 macrophage phenotype, accompanied by a gradual reduction in proliferative activity.