The influence of CD40 ligation and interferon-γ on functional properties of human monocyte-derived dendritic cells activated with polyinosinic-polycytidylic acid
Authors: Dragicevic Ana , Dzopalic Tanja , Vasilijic Sasa , Vucevic Dragana , Bozic Biljana , Majstorovic Ivana , Balint Bela , Colic Miodrag 
Published: April 2011

Background/Aim. Ligation of a Toll-like receptor (TLR) by specific TLR
agonists is a powerful tool for maturation induction of monocyte-derived
dendritic cells (MoDCs). Studies so far have shown that the treatment of
dendritic cells (DCs) with a TLR3 ligand, polyinosinic-polycytidylic acid
[Poly(I:C)], may be an appropriate activation agent for obtaining mature
MoDCs, competent to prime effective immune responses. However, little is
known about how subsequent interaction of MoDCs with T cell-derived stimuli,
such as CD40 or interferon-? (IFN-?), modulates MoDC functions. Therefore,
this problem was the main objective of this study. Methods. Immature MoDCs
were prepared by cultivation of monocytes from peripheral blood mononuclear
cells with granulocyte macrophage-colony stimulating factor (GM-CSF) and
interleukin (IL)-4 for 5 days. After that, maturation was induced by the
treatment of these cells with Poly(I:C) for 2 days. At day 6, immature MoDCs
and Poly(I:C)-activated MoDCs were incubated either with CD40 ligand
(L)-transfected J558 cells or IFN-? for additional 24 hours. Cytokine
production was measured by ELISA and FlowCytomix Human T helper Th1/Th2
11plex. Allostimulatory capability of MoDCs was tested using an allogeneic
mixed leukocyte reaction (MLR) assay. Results. Immature MoDCs showed a
moderate potential for stimulation of proliferation of CD4+ T cells, which
was enhanced by the treatment with Poly(I:C). Ligation of CD40 or treatment
with IFN-? of immature or Poly(I:C)-treated MoDCs significantly up-regulated
their allostimulatory activity. MoDCs matured in the presence of Poly(I:C)
up-regulated the production of IL- 12 and IL-10, which was followed by
increased levels of IFN- ? and decreased levels of IL-5 in co-cultures with
allogeneic CD4+ T cells. Ligation of CD40 on immature MoDCs upregulated the
production of IL-12 and IL-23 which was accompanied by increased secretion of
IFN-? in co-culture. Stimulation of CD40 on Poly(I:C)-treated MoDCs
significantly enhanced the production of IL-12, IL-23 and IL-10. However,
such treated MoDCs decreased the production of IFN-? and IL-10 and
up-regulated the secretion of IL-17. Immature MoDCs treated with IFN-?
up-regulated IL-12, but lowered the production of IL-5 and IL-17 by CD4+ T
cells. Treatment of Poly(I:C)-activated MoDCs with IFN-? down-regulated the
production of IL-12 and up-regulated IL- 10 by these cells and
increased/decreased the levels of IL-10/ IFN-?, respectively, in co-culture
with CD4+ T cells. Conclusion. Treatment with Poly(I:C) or ligation of CD40
on immature MoDCs induces maturation of these cells into a phenotype that
supports Th1 response. Activation of CD40 on Poly(I:C)-treated MoDCs shifts
the immune response towards Th17. Treatment of immature MoDCs with IFN-?
down-regulated Th2 and Th17 responses. However, addition of IFN-? to
Poly(I:C)-activated MoDCs down-regulated Th1 response and promote T
regulatory mechanisms. Each of these results may have functional and
therapeutic implications.