Term
| What are the two components that TCR interact with on the surface of a hosts cell? |
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Definition
1. a linear fragment of peptide derived from a protien antigen
2. a protein to which the peptide is bound (major histocompatibility complex[MHC] molecule) |
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Term
| the role played by the MHC in T cell responses is called? |
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Definition
| MHC restriction of T cell responses |
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Term
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Definition
| Human leukocyte antigen (HLA) |
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Term
The TCR contacts peptides bound on the groove of MHC class what? |
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Definition
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Term
Like MHC class I, MHC class II are composed of both what type of regions? |
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Definition
| polymorphic and non polymorphic |
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Term
| What is the first step in exogenous AG creation of MHC class II? |
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Definition
| the protein is internalized and contains in a vessible that fuses with endosome or lysosome which have degradative enzymes (highly acidic pH 4.0) |
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Term
What type of cells take up exogenous antigens? |
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Definition
| APC- dendritic, macrophages and B cells take up exogenous antigens |
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Term
| where are MHC class molecules made in the cell? |
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Definition
| they are made on the ribosomes of the rough ER |
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Term
| What holds the alpha and beta chains together in the exogenous creation of MHC class II? |
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Definition
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Term
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Definition
| a protien that binds to new class II's which prevent the MHC from binding to peptides in the ER |
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Term
| After the MHC class II leaves the ER where does it enter? |
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Definition
| it enters the golgi apparatus from there they enter the acid vesicle endocytic pathway |
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Term
| (exogenous) after the MHC class II enters the vesicle where the antigen has been degraded it works its way to the cell ssurface to interact with... |
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Definition
| CD4+ cell which expresses the correct AG receptor |
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Term
| After a cell has been infected, in endogenous AG, where does the processing begin? |
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Definition
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Term
| during endogenous AG processing, what cleans the protiens into peptides about 14 AAs in length? |
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Definition
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Term
| In endogenous AG processing, amino acids 8-15 long, are transported there to bind to newly made MHC class I molecules? |
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Definition
| they are transported to the ER |
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Term
| A peptide that binds to an MHC class I molecule in the endoplasmic reticulum moves via the golgi apparatus to the cell surface where it is presented to a..... |
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Definition
| CD8 T cell expressing the appropraite antigen receptor |
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Term
| processing and presentatin of endogenous antigens can occur in what type of cells? |
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Definition
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Term
| How can viruses affect MHC class 1 synthesis? |
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Definition
--some viruses synthesize proteins that interfere with the MHC class synthesis or they interrupt transport of the molecule to the cell surface,
--which decreases the MHC class I molecule expression and decreases CD8+ T cell response |
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Term
| Tumor cells frequently show decreased MHC I expression...What does this lead to in terms of NK response? |
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Definition
-This may trigger a NK--cell response.
--Normally MHC class I inhibit NK responses (prevent killing of normal cells)
-so if a cell doesnt express class I molecules, NK cells are activated |
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Term
What is cross presentation? |
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Definition
| Cross-presentation is the transferring of extracellular antigens like bacteria, some tumor antigens, and antigens in cells infected by viruses into the class I pathway for stimulation of CD8+ cytotoxic T cells(CTL). Only certain "professional" antigen-presenting cells (APCs) like dendritic cells can do this; that is, use the class I as well as the class II pathways of antigen presentation. |
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Term
| What triggers CD4+ T cells? |
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Definition
| Proteins from bacteria, most viruses, allergens, and completely harmless antigens |
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Term
What triggers CD8+ cells? |
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Definition
| infections pathogens( mostly viruses) |
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Term
What determines whether CD4+ or CD8+ will be activated?
the processing pathways or the inherent properties? |
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Definition
| The processing pathway not the properties of the Ag that determine where CD 4+ or CD8+ cells will be activated. |
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Term
What does the TCR consist of? |
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Definition
| 2 disulfide linked polypeptide chains, alpha and beta (transmembrane glycoproteins) |
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Term
The TCR alpha and beta chains contain what two regions? |
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Definition
| Variable regions (V) and Constant regions (C) similar to that Ig molecules. each folds into an Ig-like domain |
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Term
| Where is the hypervariable region on the TCR? |
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Definition
| the variable alpha and beta region contains 3 hypervariable regions or complementarity- determining regions (CDR1, CDR2, CDR3) |
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Term
| Is the TCR monovalent or multivalent? |
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Definition
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Term
| What does the TCR interact with? |
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Definition
| TCR interacts with small linear fragments of proteins called peptides, expressed on surface of a host cell in associaion with a MHC |
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Term
| antigens recognixed by TCR is generally composed of.... |
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Definition
| MHC molecules (class I or II) and a small linear peptide |
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Term
T cell activation results in... |
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Definition
| cytokine secretion and the killing of infected hosts cells |
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Term
IS there a change in the TCR during a response to an anitgen? |
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Definition
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Term
| What do CD3 and zeta chains do? |
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Definition
| they help channel a signal into the cell about changes from the TCR |
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Term
What is a co-receptor on the T cell? |
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Definition
| it is a transmembrane molecule on a mature T cell that does not bind the AG but it enhances the ability of the Ag to activate T cells, it lowers the threshold for AG responses |
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Term
| What type of cells express both CD4 and CD8? |
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Definition
| immature T cells differentiation in the thymus |
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Term
| What is the ratio of CD4 to CD8 in a an healthy individual? in a person with aids? |
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Definition
healthy- 2:1
person with aids- ratio decreases |
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Term
| Where do Cd4 and CD8 bind to on the MHC molecules? |
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Definition
| to the invariant portions of the MHC molecules expressed on the surface of hosts cells |
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Term
| What classes to CD4 and CD8 bind to? |
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Definition
CD4- class II
CD8- Class I |
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Term
| CD4 and CD8 act as what in the T-cell interactions with APC? |
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Definition
they act as adhesion molecules
they help tighten the binding of T cells to APC |
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Term
| CD4 and CD8 are involved in what after AG binds to the TCR |
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Definition
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Term
| HIV binds to what which allows it to infect all cells expressing this? |
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Definition
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Term
| What makes the TCR complex? |
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Definition
| alpha and beta chains along with the CD3 and zeta chains |
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Term
| Naive Tcells need more than first signal interaction between peptide and MHC expressed by the T cell...in addition they need... |
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Definition
· They need second signals known as costimulatory interactions. Multiple pairs of costumulatory molecules have been found on T cell and APC surfaces.
these enhance the signal delivered by the TCR complex
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Term
What is the best understood secondary signal, aka costimulatory interaction? |
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Definition
| the reaction between CD 28 on the mature T cell and B7 molecules on the APC |
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Term
| what is the primary lymphoid organ for the development of T cells? |
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Definition
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Term
| the size of the thymus decreases with the onset of puberty because of what |
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Definition
| increased steroid production |
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Term
| What is thymic involution? |
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Definition
| this is the term given to the process of the size of the thymus decreasing with the onset of puberty n mammals |
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