Term
| which has a higher antigen affinity: antibodies made during a primary or secondary immune response? |
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Definition
| secondary. Affinity is expressed as the dissociation constant (Kd) |
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Term
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Definition
| strength of all antigen binding sites combined. So--antibodies with low affinity but high avidity gives an overall good ability to bind antigen. |
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Term
| what is cross-reactivity? |
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Definition
| antigen produced against "antigen X" but may bind a structurally similar "antigen Y" |
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Term
| What is a T cell receptor? |
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Definition
| Made of alpha and beta chains. Each contains a constant and variable region. Binds to peptide with MHC molecules. |
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Term
| what is in a hypervariable region of an antibody (and a T cell Receptor)? |
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Definition
| CDR-1, CDR-2, CDR-3 with CDR-3 being the most powerful. |
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Term
| How is a T Cell Receptor (TCR) not like an antibody? |
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Definition
| both of the TCR chains are anchored in the plasma membrane. TCRs are not secreted (B cell receptors can be). TCRs do not undergo affinity maturation. They do not undergo class switching (they do not have classes: IgM etc...). Overall, they do not improve function over time like B cell receptors do. |
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Term
| What is a CDR and to what does it bind? |
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Definition
| Complementarity Determining Region that binds to a peptide (which in turn are bound to MHC molecules). |
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Term
| alpha and beta chains make up 90-95% of TCRs, what about the remaining 5-10%? |
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Definition
| gamma and delta. may play a role in defense on epithelial surfaces |
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Term
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Definition
| natural killer T cell. less than 5% of all t cells. recognizes Lipid antigens. |
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Term
| What molecules make up the TCR complex? |
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Definition
| CD3 and epsilon. Work as signal transmitters. Also needs engagement of co-receptor: CD4 or CD8 |
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Term
| what is a B cell receptor? |
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Definition
| membrane bound antibody. binds to free antigen. constant and variable regions. Recognizes conformational and linear epitopes. |
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Term
| What kind of epitopes do T cell receptors recognize? |
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Definition
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Term
| what two forms does the B cell receptor have and where are they found in each? |
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Definition
| Membrane bound: Binds antigen. Secreted Form: found in blood and mucosal secretions |
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Term
| whats in an antibody molecule? |
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Definition
| 4 polypeptide chains: 2 heavy, 2 light chains. Each light is attached to 1 heavy chain. Each heavy attached to each other at hinge region. |
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Term
| what is the Fab region on an antibody? |
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Definition
| Fragment Antigen Binding region. Binds to antigen. |
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Term
| when an antibody has a tail piece, does it function as an antibody or a B cell receptor? |
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Definition
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Term
| what are the two types of light chains? |
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Definition
| kappa and lamba. Each B cell has kappa or lamba varieties, but never both. Clinical correlate: Light Chain Deposition Disease. |
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Term
| what are the 5 isotypes of antibodies? |
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Definition
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Term
| what is heavy chain isotype switching? Found in B cells or T cells? |
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Definition
| when a progeny b cell changes from IgM/IgD into IgE, IgA, IgD. NOT FOUND IN T CELLS! |
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Term
| what is an epitope or determinant? |
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Definition
| name of specific region of antigen that binds to antibody. |
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