20 - T cells III: CTL, cytokine pattern, cross-regulation/recrptors/homing & Th1 Flashcards
Effector CD4+ T cell subsets & function
Based on what infection is –> cell-mediated response is dominated by one of the T cell subsets
TH1responses
Often involved in response to infections by viruses & intracellular pathogens
TH2 responses
Often involved in response to parasites & other extracellular pathogens & allergy
TH17 responses
Often involved in response to infections by extracellular bacteria & fungi & in causing autoimmunity
TFH responses
TFH Activating B cells in lymph node
CTL + TH1 respond to
Viruses, intracellular pathogens
TH2 respond to
Helminths & extracellular pathogens
TH17 respond to
Extracellular bacteria & fungi
Effector T cells target…
different immune cells
Th1 cells target…
macrophages
Th2 cells target…
eosinophils, mast cells, basophils
Th3 cells target…
neutrophils
cross regulation
- There will be combination of different T cells subset, but one will be more dominate
- Effector cytokines can help reinforce predominant subtype they are part of
2 patterns cross-regulate each other
IL-4 – secreted by TH2
-Inhibits TH1 differentiation
IFNy - secreted by TH1
-Inhibits TH2 proliferation
IL-4 or IFN
-inhibit TH17 differentiation
depending on what you are infected with, there will be …
a T cell subset that will dominate
Effector cytokines can help
reinforce predominant subtype they are part of
Master transcriptional regulators commit T cells to
to one subset or the other
T-Bet of TH1
suppresses TH2 pathway gene expression (GATA3) & negatively regulate Il-4,5
GATA3 of TH2
suppresses TH1 pathway gene expression (T-bet), negatively regulate IFNy
Decision point:
TGF-b
key cytokine for differentiation of both TH17/ Treg
Decision point:
IL-6 =
switch = Inducing TH17 subset differentiation instead
decision point:
Beneficial outcomes of each subset – balance between the 2 is ideal
o Normal state could favour development of iTreg population to keep inflammation down
o Infection – leading to IL-6 production – stimulate more antibacterial TH17 differentiation
Polarizing cytokines
impact differentiation of T cells – Signal 3
Effector cytokines
produced by differentiated T cells
TH1, TH2, TH17 cells
-Leave lymph node & migrate to site of infection
TFH cells
-Stay in lymph node & activate B cells
Different cell surface molecules
expressed by naïve vs effector T cells
-they travel to different locations in body (have different adhesion molecules ont ehir surface)
Effector T cells express molecules …
target them specific tissues depending on site of infection
Where effector T cell travel partly determines by
which lymph node they get activated
If activated in a lymph node that drains the skin effector T cell will up-regulate homing molecules that send them to skin
Tissue-specific molecules – target …
effector T cells to different tissues
Naïve vs. effector cells – have different
adhesion molecules
