Changes in Placental Hofbauer Cell Numbers in Histological Chorioamnionitis

Abstract

Background: Hofbauer cell (HBC), named by Isfred Hofbauer, is a cell that occurs in the placental villi from 18 days of gestation to the end of pregnancy, located near fetal blood vessels and trophoblasts, and is considered to play important role in placental formation and homeostasis. Hofbauer cells are a member of the mononuclear macrophage family, generally round long cells, 10-30㎛ in size, and exhibit pleomorphic nature with high degree of vacuolization by the plasma granules. Currently, we believe that these cells originate from stem cells of interstitial villus in early pregnancy and differentiate from fetal monocytes in the second half of pregnancy. In obstetric practice, Hofbauer cells are considered to play important role in the establishment of normal pregnancy and pathogenesis of abnormal pregnancy. The aim: We aimed to investigate the changes in placental Hofbauer cell numbers in histological chorioamnionitis. Methods: The study population included 279 placentas delivered  for the past two years. The Results: Tissue sections were obtained from the placenta, followed by conventional tissue sampling, H-E stained specimens were prepared under ×100 light microscope view, and inflammatory changes were observed, normal (control group) if no change was observed, HCAM (study group) if change was present, HCAM was again diagnosed as HCAM if inflammatory changes were present in the extrachorionic wall, and in both chorionic and amniotic membranes if they were involved in the extrachorionic wall, according to Blanc’s classification. Changes in placental Hofbauer cell numbers were performed by calculating the average number of cells in any five transverse sites under ×400 light microscope view of placental tissue samples for obstetric and clinical parameters such as amniotic fluid count, amniotic fluid phase, senescence, fetal and neonatal asphyxia (Apgar score below 7) according to the stage of HCAM. Conclusions:  The changes in Hofbauer cell numbers in histological chorioamnionitis are as follows. Hofbauer cell numbers were significantly higher, with  average of 3.1 in histological chorioamnionitis stage 1, 5.0 in stage 2, and 6.7 in stage 3, compared with the normal placenta(2.0). Hofbauer cell counts were significantly higher in all stages of amniotic fluid turbidity, senescence >2 degrees, and fetal and neonatal asphyxia in terms of obstetric and clinical parameters.