Term
| List the steps of the pathway that leads to MHC I presentation |
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Definition
Cytosolic pathway:
1. Intracellular virus/tumor digested by proteosome
2. TAP proteins allow peptides into ER
3. MHC I proteins bind to peptides in ER
4. Golgi prepares transport vesicle for MHCI complex to go to cell surface |
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Term
| List the steps of the pathway that leads to MHC II presentation |
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Definition
Endocytic pathway:
1. Extraceullar antigen endocytosed into lysosome
2. MHCII molecule transported from ER to Golgi to Lysosome with help of CLIP protein
3. CLIP segment removed within lysosome
4. MHCII and peptide bind and are transported to cell surface |
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Term
| What adhesion molecules stabilize T-cell and APC interaction? |
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Definition
Low affinity LFA1 (on T cell) and ICAM1 (on APC)
Also, CD28+B7 stabilizes |
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Term
| What is the role of IL-1 and TNF? |
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Definition
| They are inflammatory cytokines that further activation signals for the APC and the T-cell |
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Term
| What processes do all T-cells undergo after interaction with a matching APC? |
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Definition
1. Activation
2. Proliferation
3. Differentiation |
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Term
| After becoming activated, what do Cytotoxic T cells do? |
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Definition
| Cytotoxic cells travel to infected tissue where virus-infected cells present specific antigen |
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Term
| After becoming activated, what do effector TH1 cells do? |
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Definition
| Effector TH1 cells travel to infected tissue to activate matching macrophages via cytokines |
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Term
| After becoming activated, what do effector TH2 cells do? |
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Definition
| Effector TH2 cells activate, via cytokines, antigen-specific B cells to become plasma cells and make antibodies in the lymphoid tissue |
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Term
| What T-cell subsets fall under CD4+? |
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Definition
Most helper T cells
Effector delayed hypersensitiviy (DTH) cells, which act as "cytokine factories" |
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Term
| What T-cell subsets fall under CD8+? |
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Definition
| Most cytotoxic T cells (CTL), which kill through apoptosis |
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Term
| Define antigen-reactive T cells |
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Definition
| Mature naive CD4+ and CD8+ T cells |
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Term
| There are few T-cells which can interact with any given epitope. How are these cells activated to clone during an infection? |
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Definition
After immunogen activation (but not before), IL-2 receptors become present on T-cells
IL-2, produced by mature naive helper T CD4+ cells, promotes expansion of a T-cell clone |
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Term
| What does IL (as in IL-2) stand for? |
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Definition
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Term
| What is the role of cyclosporine? |
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Definition
| Cyclosporine is an immunosuppresive drug that blocks the production of IL-2, thereby blocking activated T-cell clonal expansion |
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Term
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Definition
An intermediate between mature naive T cells and TH1 or
TH2 cells, depending on what cytokines are present
Secrete INF-γ and IL-4 |
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Term
| What four cells can a TH0 cell become? |
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Definition
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Term
| What is the role of TH17? |
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Definition
| To make inflammatory IL-17 |
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Term
| What will cause a TH0 to become a TH1? |
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Definition
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Term
| What will cause a TH0 to become a TH2? |
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Definition
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Term
| What cytokines do TH1 produce? |
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Definition
| IL-2, TNF-γ, and tumor necrosis factor beta (TNFβ) |
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Term
| How do TH1 cells promote macrophage activity? |
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Definition
| By enhancing intracellular killing via cytokines and by inducing the isotype switch in B cells to IgG1 for which macrophages have Fc receptors |
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Term
| What cytokines do TH2 produce? |
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Definition
| A variety of interleukins (IL-4, 5, 6, 10, and 13) |
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Term
| What cells do TH2 cells promote? |
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Definition
Various inflammatory cells (mast, basophils, eosinophils) as will as the isotype switch in B cells to IgE
This is antiparasitic |
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Term
| For TH1 and TH2 cells, which promotes humoral and which promotes cell mediated immunity? |
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Definition
TH1- cell mediated
TH2- humoral |
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Term
| How do TH1 and TH2 cells activate each other? |
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Definition
Trick question- they mutually inhibit each other
The balance between the two is significant in infectious diseases, autoimmunity, and allergy |
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Term
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Definition
T regulatory cells
-Inhibitory for inflammatory and other responses
-Produce IL-10 and TGFβ
-Play roles in mucosal immunity, allergy, and cancer
-Has an IL-2 receptor |
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Term
| What cytokines do Treg cells produce? What do they do? |
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Definition
IL-10 and TGFβ
They suppress autoreactive T-cells (Both TH1 and TH2)
(Why Treg cells suppress allergy and prevent anti-tumor responses) |
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Term
| What interleukin leads to TH17 cell production? |
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Definition
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Term
| What is the role of TH17 cells? |
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Definition
Promote inflammation by producing IL-17
Appear to have a role in mycobacterial surveillance
Commonly found in inflammatory disease tissue (RA, MS, IBS) |
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Term
| What is the basic function of a killer T cell? (aka CD8+ cell) |
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Definition
| Induce apoptosis in virus infected cells, cells infected with other intraceullar pathogens, and allographs |
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Term
| List the two ways a killer T cell can induce apoptosis |
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Definition
1. Toxin mediated apoptosis
2. Receptor/direct mediated apoptosis |
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Term
| Define toxin mediated apoptosis |
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Definition
| Killer T cell releases perforins that form pores in the target. Cytotoxins enter the pores and cause apoptosis. |
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Term
| Define receptor/direct mediated apoptosis |
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Definition
| Fas-ligand on killer T cell activates Fas on target resulting in programmed cell death. |
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Term
| List two cells with IL-2 receptors |
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Definition
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Term
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Definition
Both CD4 and CD8 T cells can differentiate into memory cells after stimulation. They are more efficient in a secondary immune response.
(However, sheer numbers of antigen-reactive cells account for most of the characteristics of the secondary immune response) |
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Term
| How do natural killer (NK) cells recognize an infected cell? |
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Definition
NK cells have Fc receptors that crosslink and recognize antibodies, so they can kill the cell the antibodies are attached to
NK cells also recognize the lack of normal MHC as vulnerability to attack |
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Term
| What is the major difference between NK cells and cytotoxic T cells? |
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Definition
| NK cells are not immunogen-specific or MHC-restricted |
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Term
| Where are NK cells found, and how common are they? |
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Definition
| NK cells make up 10-15% of circulating blood lymphocytes and occur in significant amounts in the spleen, mucosa, and liver |
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Term
| What pathogens are NK cells an important first line of defense against? |
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Definition
| Viruses and other intracellular parasites |
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Term
| What receptors do NK cells possess? |
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Definition
Both inhibitory and activating
2 activating receptors are IL-2 and Fcγ receptors |
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