T cells Flashcards
CD 4 T cells Function
- Activate Naive B Cells
- Secrete cytokines that help macrophages become more bactericidal.
CD 8 T cells function
Kill host cells that contain intracellular bacteria (MHC class 1 presented by infected cells.)
What do T cells require for activation?
- Requires antigen from APC and costimulation
- B7 (APC) + CD28 (T cell
What do TH1 cells do?
- They secrete IFN-gamma which activates microphages
- stimulates IgG production
What do TH2 cells do?
- Secrete IL-4, IL-5, IL-13
- Mast cell and eosinophil activation;
- IgE production
- Defends against parasites.
What activates APCs
- Pathogen Associated Molecule Patterns
- Ex. LPS (Lipopolysaccharides ) on gram negative bacteria
- cytokines such as interferons, TNF
MHC-1 vs. MHC-II site of peptide loading
MHC-I: Endoplasmic Reticulum
MHC-II: Endocytic vesicles
CD8 T cell function
-contains granules that can kill virus-infected cells
MHC-I
-HLA-A, HLA-B, HLA-C
MHC-II
-HLA-DP, HLA-DQ, and HLA-DR
Polymorphic meaning
Variation between alleles
Does MHC undergo somatic gene recombination?
No, they don’t change over life of an individual.
What does type I IFNs do?
- ncrease RNAse and MHC-I in neighboring cells.
- Decrease protein synthesis.
- change gene expression
NK cell function
- kills antibody-coated cells via ADCC (antibody depedent cellular cytotoxicity)
- checks total level of MHC not the antigen peptide.
- contains both activating and inactivating receptors.
- kill target cells with similar mechanism to CD8 T cells
Activated by:
1) decrease in MHC class I
2) Activating ligand/receptor
Which cytokines play a role in acute phase response?
Liver: IL-1, IL-6 to help liver create proteins such as C-reactive protein and mannose-binding lectin.
Brain: TNF, IL-1, IL-6 to induce fever
Bone marrow: TNF, IL-1, IL-6 to stimulate neutrophil production.
