Dendritic Cell Subsets

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Dendritic Cell Subsets June 3, 2005 MIMG
261 Stephan Krutzik, Ph.D. skrutzik_at_mednet.ucla.ed
u
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Dendritic cell (den-'dri-tik 'sel) A cell found
in the T-cell area of lymphoid tissue with a
branched or dendritic morphology that is the most
potent stimulator of T-cell responses. Non-lymphoi
d tissue also contain dendritic cells, but these
are not able to stimulate T-cell responses until
they are activated and migrate to lymphoid tissue.
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• Myeloid dendritic cells
• Tissue DC- sites of host pathogen encounter
• respond to bacterial and viral infections
• Trigger Ag-specific T cells
• First identified 1973 as spleen cells with
  tree-like processes

• Plasmacytoid dendritic cell
• circulating DC, lymphoid tissue
• respond to viral infection and produce large
  amounts of IFN-a
• Trigger Ag-specific T cells
• First appreciated as DC in 1997

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Human dendritic cell subsets
Human dc can be distinguished based on key
features
Myeloid markers
lymphoid markers
function
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Mouse dendritic cell subsets
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TLR expression in dendritic cell subsets
Mouse
Human
GM-CSF IL-4
TLR1 TLR2 TLR3 TLR4 TLR5 TLR6 TLR8
TLR1 TLR2 TLR4 TLR5 TLR6 TLR8
TLR7 TLR9
TLR1 TLR2 TLR3 TLR4 /- TLR6 TLR9
TLR1 TLR2 TLR3 TLR5 TLR6 TLR7
Iwasaki et al Nat Imm
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LANGERHANS CELL

• Discovered in 1868 by Paul Langerhans
• Specialized myeloid dendritic cell in both mouse
  and human
• Represent 2-3 of all epidermal cells
• Located in suprabasal layers of epidermis
• Member of the dendritic cell family of
  professional APC
• Are critical for the generation of T cell
  responses to haptens, proteins, and alloantigens

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The life of a myeloid dendritic cell

• Antigen capture (maturation)
• Migration to lymph node
• T cell activation

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Modes of maturation Danger Signals Non-self TLR
ligands (PAMPs) Self CD40L, TNF-a, IL-1, IL-6,
IFN-a
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DC maturation upon activation with TLR ligand
media
immature Dendritic cell
TLR2/1
TLR
TLR2/1
TLR4
Mature Dendritic cell
Maturation leads to increased expression of
co-stimulatory molecules, CD80, CD86 and higher
levels of MHCII
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CCR7 is induced upon DC maturation
Mature Dendritic cell CCR7
immature Dendritic cell CCR2, CCR4, CCR6, CXCR3
CCR7 ligands CCL19 and CCL21, are expressed by
stromal cells in the T cell zone of the lymph
nodes
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CCR7 deficiency affects DC migration
Anti-DEC205 (LC marker) staining
Lymph node single cell suspension
Forster et al Cell 1999
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CCR7 deficiency affects T cell activation
Adoptively transfer CFSE-labeled OT-II cells
WT
CCR7-/-
OVA /- CpG
OVA /- CpG
72hr
72hr
Proliferation
Proliferation
CFSE Carboxy-fluorescein diacetate, succinimidyl
ester
Ohl et al Immunity 2004
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Role of dendritic cells in T cell activation
IL-12
Antigen presentation molecules
Human MHCI MHCII CD1a, b, c, d
Mouse MHCI MHCII CD1d
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Mouse myeloid dendritic cell subsets
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Mouse myeloid dendritic cell subsets trigger
distinct T cell responses
CD8 and CD8- DC were isolated from spleen,
loaded with KLH peptide and injected into footpad
of syngeneic mice LN harvested and reactivity
toward KLH was measured
Th2
Th1
CD8-
CD8
Maldonado-Lopez et al J Exp Med 1999)
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CD8 DC drive Th1 T cells via IL-12
Lack of Th1 skewing in IL-12 p40 -/-
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Phagocytosis
Antigen presentation
Maturation
Migration
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(No Transcript)
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Plasmacytoid Dendritic Cells
Innate immunity Secrete high levels of IFN-a
Adaptive immunity Trigger T cell activation
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Plasmacytoid dendritic cells Interestingly,
pathologists have long observed the presence of
plasma cells that express the T cell marker CD4
and lack intracellular immunoglobulins within the
T cell zones of human lymph nodes. These plasma
cells were suggested to represent terminally
differentiated T plasma cells of unknown
secretory functions. Paradoxically, these so
called plasmacytoid T cells were found not to
express other T cell markers such as CD3 and
TCRs. They expressed MHC class II antigens,
HLADR and HLADQ, and the invariant chain CD74.
Early on (1970s) an IFN-a producing MHCII
leukocyte was observed but could not be
identified--interferon producing cell
(IPC) Found in circulation and in lymphoid
tissue Lymphoid origin based on expression of
pre-T cell receptor and IgH D-J
recombination Flt3 ligand part of their
development
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Discovery of plasmacytoid dendritic cell
Characterized peculiar plasmacytoid T cell in
tonsil area that was CD4 but lacked lineage
markers for T cell, B cell, monocytes, Langerhans
cells, granulocytes
Depletion using lineage specific
antibodies CD4CD11c-CD3- sorted
Freshly isolated pDC undergo apoptosis
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pDC survival is IL-3-dependent
pDC undergo apoptosis unless cultured with IL-3
pDC cultured with IL-3 have an immature DC
phenotype
Grouard, j ex med 1997
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Plasmacytoid dendritic cells have capacity to
trigger T cell proliferation
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Unique features of plasmacytoid dendritic
cells Express high levels of CD123
(IL-3Ra) CD11c- (CD11clo in mouse) Express TLR7,
TLR9 Secrete high levels of IFN-a CD45RB, CD45RA,
B220, Ly6 (mouse)
Can be sorted using CD123 (IL-3Ra), DR, Lin-
(CD3, CD14, CD16, CD19, CD56) CD11c-, CD4, Lin-
(human) BDCA-2 or BDCA-4 (human) CD11c, B220
(mouse)
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Migration of plasmacytoid dendritic cells
lymphatics
mDC first travel to nonlymphoid tissue and then
to lymphoid tissue pDC travel directly to
lymphoid tissue
Migration dependent on CD62L and CCR7 which
interact with HEV and CCL19, CCL21 (expressed by
stromal cells and HEV in T cell rich area of
lymph node)
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activated pDC
Unactivated pDC
Antigen presentation
IFN-a
Colonna et al Nat Imm
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pDC function T cell activation and polarization
IL-3 CD40L
OX40L
Th2
pDC
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pDC-derived DC induce Th2 responses
7 days
CD3/CD28
CD40L
ELISA
mDC or pDC
pDCCD11c-, CD4, Lin- mDCmonocytes (GM-CSF
IL-4 5 days)
Rissoan et al Science 28319 1999)
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pDC-derived DC can also induce Th1 responses
7 days
PMA/ionomycin
R-848 or IL-3
Intracellular flow
pDC
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Plasticity of pDC-derived DC
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Human plasmacytoid dendritic cells have a unique
TLR expression pattern
TLR7- ssRNA TLR9- CpG DNA
Expression of TLR7, TLR9 allow pDC to detect
viral invasion and initiate immune response
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pDC function continued A major role of pDC
during viral infection is the secretion of high
levels of type I interferons (IFN-a, IFN-b) Type
1 interferons have a very global impact on the
immune response
PBMC
pDC2-dep
pDC2-enrich
pDC2
CD11cDC
Mo
DC1
DC2
Exp. 1
500
ND
2,800
89,800
120
ND
lt12.5
1,100
Exp. 2
40
lt12.5
180
20,000
lt12.5
350
lt12.5
lt12.5
Exp. 3
700
40
2,800
638,000
70
90
ND
ND
HSV infected cells
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pDC have a broad impact on immune response via
IFN-a
IL-12
monocyte
Mature Dendritic cell
Th1
immature Dendritic cell
MHCI
TLR ligand (TLR7, TLR9)
generic cell
IFN-a
Plasma cell
B cell
cytotoxicity
NK cells
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pDC have a broad impact on immune response
Th2
OX40
OX40L
CD40L CpG
IFN-a
Tr cells (CD4CD25)
T cells (CD4CD25-)
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Myeloid vs. plasmacytoid dendritic cell