Immuno 4 Leuk traff
Card Set Information
Immuno 4 Leuk traff
Central lymphoid organs?
Peripheral lymphoid organs?
1- thymus and bone marrow
2- Lymph node, Spleen, MALT
Primary Lymphoid Follicle:
Secondary Lymphoid Follicle:
: T cells + B cells
: macrophages + plasma cells
Primary Lymphoid Follicle
: resting B cells
Secondary Lymphoid Follicle
: with GERMINAL CENTERS (site of intense Bcell proliferation)
How does a DC in the tissues know to go to the LN?
it has TLR receptors (which recognize PAMPs on microbes)
it has TNFalpha and IL-1 receptors (which recognize inflammatory cytokines produced by macrophages at the site of inflammation)
What changes occur when a DC is activated?
: becomes antigen presenting (instead of immature antigen capturing DC):
Increases expression of 2 signals required for Tcell activation:
1. MHC 1 and 2
2. Costimulatory Molecules (B7-1
: CD80, CD86)
What pulls the activated DC into the LN?
Activated DC's increase expression of
which binds to:
CCL19 and CCL21
chemockines in the Tcell zone (paracortical area) of the lymph node
Naiive B-cells express:
Naive B cells
in the follicles of the LN
How does the spleen serve a similar function to the lymph nodes response to lymph-borne antigens?
Blood-bourne antigens go to the spleen--> travel through the red pulp sinusoids --> arrive at the WHITE PULP (lymphocyte-rich region) near artery -->
Tcells go to Periarteriolar lymphoid sheaths
& Bcells go to the follicle
Naiive T cells express:
Naiive T cells
L-Selectin (CD 62L)
which binds with LOW AFFINITY to
on the endothelial cells lining the HEV (high endothelial venule)
and induces rolling of the Tcell
Once the Tcell gets to the LN and CCR7 binds CCL19 + CCL21, what happens?
binding of CCR7 + CCL19/CCL21 causes expression of
HIGH AFFINITY integrins
LFA-1 and VLA-4
which induce high affinity binding of Tcell to HEV (and cause migration into the LN stroma)
*B cells have similar mechanism
What changes occur in an Activated T cell?
: L-selectin + CCR7
: Adhesion molecules and chemokine receptors:
^E-selectin (CLA-1), CCR4, CCR10
which bind to inflammatory cytokines at the endothelium of infection sites
CCL 17 + CCL27
Effector Bcells are homed to:
Effector Bcells are homed to the bone marrow (where they set up shop as long lived plasma cells)
: Bcells that produce IgA isotype Ab: often traffic to the mucosal sites