Term
| What are antigen presenting cells? |
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Definition
| cells that phagocytose pathogens and then present small protein antigens from these pathogens on their surface |
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Term
| What are pathogens on antigen presenting cells bound by? |
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Definition
|
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Term
| What recognized the MHC/antigen complexes on APC? |
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Definition
| T cells via the T cell receptors |
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Term
| What are the different types of antigen presenting cells? |
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Definition
| dendritic cells, macrophages, and b cells |
|
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Term
| What are dendritic cells? Where do they primarily do this? |
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Definition
| specialized imune cells that take up pathogens and soluble antigen and present it to T cels; in the lymph node |
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Term
| How do macrophages present antigen to T cells? where do they do this? |
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Definition
| phagocytose pathogens to present antigens to T cells; in the lymph nodes and at the site of infection |
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Term
| What type of antigen can B cells take up to present to T cells? Why is this important? |
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Definition
| soluble antigen; for B cell activation |
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Term
| What part of the T cell interacts with the antigen/MHC complex? |
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Definition
| T Cell receptor alpha/beta subunits |
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Term
| What do the intracellular subunits of the T cell do? |
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Definition
| transmit signals inside the cell once a pathogen is bound to the receptor |
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Term
| How many receptors does a T cell have? |
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Definition
| one can only recognize one or a small number of antigens |
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Term
| How are the Variable regions of the TCR alpha/beta chains produced? what does this mean? |
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Definition
| gene rearrangement; each mature T cell expresses it own alpha/beta region that can ecognize one or a small number of peptides |
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Term
| What presents pathogenic antigens to T cells? |
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Definition
| Major Histocompatibility complex |
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Term
| What type of cells is MHC class I expressed on? What type of cell recognizes MHC class I? |
|
Definition
| nucleated cells (human); CD8+ cytotoxic T cells |
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Term
| What type of cells is MHC class II expressed on? What type of cell recognizes MHC class II? |
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Definition
| antigen presenting cells; CD4+ helper T cells |
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Term
| What is the basis of tissue typing for organ transplantation? |
|
Definition
| variation in MHC proteins |
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Term
| What are alleles? How many does each MHC gene have? |
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Definition
|
|
Term
| how many seperate MHC class I and MHC class II genes do humans express? |
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Definition
|
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Term
|
Definition
| increase the responsiveness of the TCR to the antigen/MHC complex by 10-100 fold |
|
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Term
| Which co-receptor is expressed on T helper cells? what do they bind to? |
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Definition
|
|
Term
| Which co-receptor binds to MHC class I? What is it expressed on? |
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Definition
|
|
Term
| What is the purpose of CD4 and CD8? |
|
Definition
| to strengthen the TCR/antigen/MHC interaction and facilitate the activation of intracellular signals |
|
|
Term
| How many signals do T cells require to undergo full activation? When does each happen? |
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Definition
| 2; signal 1: occurs upon TCR stimulation, signal 2: occurs upon costimulatory receptor activation |
|
|
Term
| Where are costimulatory receptors or their ligands expressed? |
|
Definition
|
|
Term
| What is important for supressing autoreactive T cells? |
|
Definition
|
|
Term
| What is the purpose of costimulation? |
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Definition
| so that T cells dont kill your host cells |
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|
Term
| What does APC mediated actication of CD8 T cells lead to? |
|
Definition
| proliferation and differntiation into armed effector cells |
|
|
Term
| What is the effector function? |
|
Definition
| goes to site of infection and looks for cells that are expressing pathogens and kill them |
|
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Term
|
Definition
| granulocytes that are derived from lymphoid progenitor cells |
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Term
| Why do NK cells take action instead of CD8 cells? |
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Definition
| some cancer cells or cells infected with viruses decrease their expression of MHC class I to evade CD8 cells |
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|
Term
| How do NK cells kill cells? |
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Definition
| look for cells that have down regulated MHC class I and they release granules that directly kill them |
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Term
| What do CD4 T cells differentiate into? |
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Definition
| multiple effector T cell subsets (more refined in they way they kill and fight things) - need to differentiate into the correct subset so that the pathogens can be destroyed |
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Term
| What happens to the population of T cells during an infection? |
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Definition
| first they expand after the latent period, then they contract (90% die off the rest become memory cells) |
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|
Term
| What is DiGeorges Syndrome? |
|
Definition
| where a human doesnt have a thymus so there is a severe defects in the number of mature T cells (don't have T cell mediated responses) |
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Term
| Where is the thymus found? |
|
Definition
| above the heart behind the sternum |
|
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Term
|
Definition
| after the thymus increases in size until puberty, it is then replaced slowly by fat |
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Term
| What happens to T cells that have unproductive or self reactive TCRs? how many does this happen to? |
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Definition
| they undergo apoptosis in the thymus, 90% |
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Term
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Definition
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