CMI and Humoral Immunity Flashcards
Dendritic cells express costimulatory molecules:
- CD40L:CD40
- CD28:B7.1 or 7.2 (CD80 or 86)
p-SMAC:
Peripheral Supramolecular Activation Complex.
- Stabilizes T-cell:Dendritic cell interaction.
Binding of MHC to TCR leads to:
ITAM phosphorylation by Lck.
TCR signaling leads to the formation of 3 transcription factors (IL-2 promoter):
- NFAT
- NFkB
- AP-1
Peripheral tolerance:
Self reactive T cell escaped thymic selection sees self antigen but no costimulation = anergy/apoptosis.
Th0 gives rise to (5):
- Th1
- Th2
- Th17
- Tfh
- Tregs
Th0 –> Th1
IL-12
Th0–> Th2
IL-4
Th0 –> Th17
IL-23
Th0 –> Treg
TGF-beta
Th0 –> Tfh
IL-21
Th1 secrete:
- IL-12
- IFN-gamma
Th17 secrete:
- IL-17
- IL-6
Th2 secrete:
- IL-4
- IL-5
Tfh secrete:
- IL-21
- IL-10
- TGF-beta
Treg secrete:
- TGF-beta
- IL-10
CTL killing:
- Rapid.
- Requires cell:cell contact.
- Uni-directional.
- CTL can kill multiple targets.
- Bystander cells unaffected.
3 steps to CTL killing:
- CTL target binding.
- Initial contact independent of antigen (Mg dependent).
- Granule reorientation
- Programming the target for lysis (Ca2+ dependent).
- Target cell death.
Proteins in granules of CTL cells (3):
- Perforin.
- Granzymes.
- Granulysin.
Perforin:
Aids in delivering contents of granules to cytoplasm of target cell.
Granzymes:
Serine proteases which activate apoptosis once in the cytoplasm of target cell.
Granulysin:
Has antimicrobial actions and can induce apoptosis.
IL-7
Required for T cell survival.
3 types of memory cells:
- Central.
- Effector.
- Resident.
Memory cells that do not circulate:
Resident Memory Cells.
Memory cells remain in lymphoid tissue:
Central memory cells.
Memory cells that migrate to tissues:
Effector memory cells.
nTregs:
Natural Tregs
- Derived in thymus, suppress immune function nonspecifically.
iTregs:
Induced Tregs
- Antigen specific inhibition.
MDSC:
Myeloid Derived Suppressor Cells
- Granulocyte or monocyte like.
- Inhibit T cell response via arginase production.
- Release TGF-beta.
