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34 Cards in this Set
- Front
- Back
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What is the function of CD3? |
CD3 is linked to the TcR. Long tails activate tyrosine kinases once the TcR is bound. This initiates T cell signalling. |
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What is the function of CD4? |
Exists on T cells and binds to MHC class II. Not on the MHC receptor. Aids binding of Tcr to MHC class II. Drags Ick enzyme to CD3. |
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What is the function of CD8? |
Binds to MHC class I and Ick, same as CD4 but in CD8+ cells. |
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What is the function of CD28? |
Binds to CD80 and CD86 which exist on APC's. CD28 binding leads to the production of IL-2. |
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What is the function of CD40L? |
The CD40 ligand controls differentiation of activated T-cells. |
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What is the function of the goblet cell? |
Traps microbes, Secretes mucus, prevents adhesion. |
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What is the function of a mast cell? What do their granules contain? Why are they such effective cells? |
- To raise the alarm. When detecting a pathogen they granulate. - Histamine, LTB4, Cytokines and Chemokines. - They granulate rapidly. FAST RESPONSE |
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What is the function of LTB4 and Histamine? |
They increase the permeability of the capillary wall. Allowing more fluid and cells to pass through the capillary wall. Causes inflammation. |
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What is the function of neutrophils? |
They contain an array of anti pathogenic mediators. They degranulate and release these chemicals in response to tissue damage or infection. Can also kill by phagocytosis or NETtosis. |
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What is an eosinophil? |
A granulocyte which responds to infection in a way similar to neutrophils. |
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What are chemokines? In what way are cytokines specific? What effects can cytokines bring about? |
Chemokines are proteins which are secreted by immune cells and stromal cells. They attract cells which have a specific receptor, unique to that specific cytokine. Life span, motility, proliferation, motility... |
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What is TNFalpha? What does it do? |
A chemokine, released by granulocytes. TNF alpha binds to TNFR1 and enhances killing capacity of neutrophils. |
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Describe the cytokine network. |
Cytokines are released by granulocytes. They can cause release of more cytokines by other cells, meaning a signal can be transported to other immune cells. |
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What are toll like receptors? |
Receptors which detect PAMPS in pathogens. Identifies a pathogen and initiates an immune response. Different TLR's recognise different PAMPS. |
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What is chemotaxis? |
When immune cells move up a concentration gradient of chemokines to the source of infection. |
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What causes chronic inflammation? What cells predominate this kind of inflammation? |
A long term pathogen or autoimmunity that causes continuous immune activation. Macrophages |
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What cells are found in an acute immune response? |
NEUTROPHILS |
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What cells do dendritic cells activate? How do dendritic cells detect foreign pathogen? What other function do dendritic cells carry out? |
- CD4+ T cells - Recognition by Toll like receptors - They express costimulatory molecules when activated. |
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What is immunological tolerance? Why must tolerance exist? What occurs when tolerance fails? |
Where an antigen that would usually initiate an immune response is ignored. So that immune responses are not triggered on self antigen. Autoimmunity |
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Why must tolerance exist, why cant we not produce antigen that are non-self? |
B and T cell receptors are produced by random genetic mechanisms in order to increase the specificity of the immune system. Sometimes the immune system produces antigen which recognise self. These must be eliminated or turned off. |
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What is central tolerance? What is peripheral tolerance? |
- Tolerance to self antigen. Affecting immature B + T cells. Ensures they dont attack the cells which create them. - Affects mature lymphocytes. Prevents cells from reacting to HARMLESS NON-SELF antigen (breast milk, hormones) |
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Define the following: - Ignorance - Clonal deletion - Clonal anergy - Active regulation |
- Where lymphovytes never come into contact with self cells and so cannot activate immune response (lens of the eye) - When lymphocytes react to the cells which are creating them in thymus or bone marrow. Cell death. - When a t-cell recognises antigen without co-stimulation. Anergy (left to die) - When a T cell differentiates into a helper T cell after encountering antigen. |
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How does a lymphoid stem cell become a t cell? What happens after? What happens when a t cell reacts to antigen? |
Precursor cells leave the bone marrow and migrate to the thymus. They express genes for the TCR and undergo positive and negative selection. They migrate to TDA's like the spleen and lymph nodes - They become effector cells, or survive as memory cells. |
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What are natural regulatory T cells? What controls development of T(reg) cells? What is the phenotype of T(reg) cells? |
- T cells which produce IL10 and TGF(B). Unusually have affinity for self antigen. - Transcription factor FoxP3 - CD4+ CD25+ |
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T cell production is extremely wasteful. Why is it "worth it"? |
T cells can live for a long time, and are highly specific, allowing vast immune response. |
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What do the following cells do?: Helper T cells Cytotoxic cells Regulatory T Cells Memory T cells NK T cells |
- Produce cytokines, produce antibody for B lymph, activate macrophages. - Kill tumour cells and infected tissue. - Inhibit lymphocytes, prevent autoimmunity - Generate rapid 2nd response - Early response. Link adaptive and innate immune system |
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What functions do CD4+ cells and CD8+ cells carry out? |
CD4+ are generally helper t cells or T(reg) cells. CD8+ are generally cytotoxic. |
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What are NK T lymphocytes? |
Not MHC restricted, recognise lipids and produce large amounts of IL-4 and INF gamma early in immune response. NATURAL KILLERS |
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Why is the MHC considered Polygenic? |
Because it is comprised on a collection of linked genes. |
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What is the main structural difference between MHC class I and MHC class II? Describe the cellular differences of MHC class I/II cells. |
Size. Class I are 9 amino acids, where Class II is 24+ MHC class 1 presents endogeneous antigen to cytotoxic CD8+ cells. Class II presnet exogenous antigen to CD4+ helper cells. |
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MHC class I cells are suicidal for the greater good. What does this mean? |
They present antigen to CD8+ t cells. This will result in the destruction of the cell. |
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What is the more efficient cell death, Apoptosis or Necrosis? Why? |
- Apoptosis. Apoptotic bodies are easily consumed by Macrophages/other cleaning cells. Necrosis causes cell contents to be released into the extracellular fluid. Causes INFLAMMATION. |
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What is opsonisation? |
Antibody binding to a pathogen promotes phagocytosis by macrophages etc. |
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Continue from Autoimmunity |
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