Phenotype and function of monocyte-derived dendritic cells in neonates
born to Hepatitis B virus-positive mothers
Abstract
Hepatitis B Virus (HBV) infection in infancy or early childhood leads to
high rate of persistent infection (25-90%). The immunological basis of
high rate of viral persistence in vertically acquired HBV infections is
not completely understood. Dendritic cells (DCs) are one of the most
potent antigen-presenting cells (APC) and play pivotal roles in the
enhancement or regulation of antiviral immune reactions. Aim of the
present study was to investigate whether an HBV-infected maternal
environment might influence the infants’ DC phenotype and function.
Monocyte-derived DC (MoDC) of neonates born to HBsAg-positive mothers
were studied phenotypically by Flow Cytometry (FCM) and functionally by
mixed lymphocyte reaction (MLR) and enzyme-linked immunosorbent assay
(ELISA). An electron microscope was used to analyze the morphological
changes of MoDC. MoDC from neonates whose maternal HBV DNA
was>5×107 copies/ml showed a reduced surface expression of
CD80, CD86, and HLA-DR as compared to that in neonates whose maternal
HBV DNA was negative (CD80: t=3.238, P=0.002; CD86: t=3.543, P=0.001;
HLA-DR: t=2.785, P=0.008). T-cell proliferation assays also showed an
impaired allostimulatory capacity in comparison to that in neonates
whose maternal HBV DNA was negative, especially in the cultures at a DC:
T cell ratios of 1:5 and 1:10 (t=-5.442, P<0.001; t=-2.195,
P=0.042). Therefore, it can be speculated that the presence of high
level of HBVDNA in the maternal environment might lead to minor
phenotypic and functional alterations of MoDC from neonates and
subsequent deficits in T-lymphocyte activation may contribute to viral
persistence.