T Cells 1 Flashcards
describe the activation of proliferation vs differentiation
- proliferation activated by IL-2 from signals 1 + 2
- differentiation activated by signal 3
when does clonal expansion occur relative to differentiation?
at the same time
what are the 4 general steps for production of effector T cells?
- APC presents antigen to naive T cell
- signal 1+2 produces IL-2
- cytokines release to cause clonal expansion/differentiation (signal 3)
- production of effector T cells with effector functions
what are the general functions of effector CD4+ T cells?
Activation of macrophages, B cells, other cells
what are the general functions of effector CD8+ T cell?
killing infected target cells, activating macrophages
what cells do T follicular helper cells activate?
B cells
what are the 3 signals for activation of B cells by T follicular helper cells?
- p:BCR
- Th2 cytokines + TCR:pMHCII + CD40L:CD40
- linked recognition
what is a function of TH1 cells?
activate macrophages
what is a function of Tc cells?
directly kill infected cells
what is the only type of effector cell that CD8+ T cells can become?
Cytotoxic
what are the 5 steps once T cells leave the lymph node?
- efferent lymphatic vessel
- thoracic duct
- bloodstream
- site of infection
- cell-mediated immunity
what do Th1 cells do to Tc cells?
promote killing by Tc cells and ROS killing by macrophages
what 3 things happen after infection is cleared?
- T cell activity downregulated
- immunological memory produced
- restoration of epithelial integrity
what is the difference in cytokine signals for proliferation and differentiation?
proliferation is AUTOCRINE mechanism
differentiation is PARACRINE mechanism
how is differentiation a paracrine mechanism?
APC produces cytokines that act on the naive T cell
what is another name for a naive CD4+ T helper cell?
TH0
what determines the type of effector cell that is produced?
cytokines produced for signal 3
what type of cells produce regulatory T cells?
CD4+ T cells
what 2 things allow for lymphocyte activation?
proliferation + differentiation
what do effector T cells result from?
effector T cells result from differentiated T cells from activated T cells
T cells can be classified depending on: (3)
- TFs they express
- cytokine profile they make
- main function in adaptive immunity
what determines the specific type of effector T cell produced?
the PAMP that binds to the APC
do effector T cells require co-stimulation to act?
NO
What does VLA-4 do?
binds receptors on endothelial cells near inflamed tissue
what do selectins do?
targets naive T cells to HEVs to enter the lymph node
what determines the fate of T cells?
cytokines
what are the 5 subtypes of effector T cells?
- TH1
- TH2
- TH17
- TFH
- Treg
what is the name for signal 3 cytokines?
polarizing cytokines
what is the role of polarizing cytokines?
guiding a T cell towards an effector fate
what polarizing cytokine do viruses stimulate? which type of T cell? what about worms?
viruses: IL-12 –> induces TH1
worms: IL-4 –> induces TH2
what are the 4 steps of signal 3?
- signal 3 cytokines bind receptor on T cell
- STAT proteins phosphorylated
- STAT proteins activated and act as TFs for another TFs
- the 2nd TF produces cytokines to determine activity of activated, differentiated T cell