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30 Cards in this Set
- Front
- Back
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what is a paratope
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an antibody combining site for epitope located in the first domain of the Fab limb of the immunoglobulin)
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why is it important for antibodies to be poly valent
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For example, if you go from binding one Fab (paratope) to one antigenic determinant (epitope), the intrinsic affinity, to binding two paratopes of IgG, that functional affinity, that bivalency confers about a 1,000-fold increase in the strength of the antigen-antibody interaction. Thus by going from one to two binding sites we have an increase of 1,000 fold in functional affinity. If it were one to ten (where all IgM paratopes are binding epitopes the increase in functional affinity would be 10,000,000. Therefore, the bivalency or poly valency of antibody confers on it an enormous advantage in terms of binding antigen.
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what is avidity
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This is the average of the functional affinities of antibody molecules.
It is important-to note that-the affinity is fundamental to an appreciation of antibody specificity |
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what are the different types of antigen / antibody forces of attraction
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(i) hydrogen binding (ii) electrostatic forces (iii) Van der Waals forces* (iv) hydrophobic interactions (these are the most important and account for about 50% of the binding energy between paratope and epitope
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A broad division can be made with respect to the types of tests that we use to examine these antibody/antigen interactions:
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(i) those in which antigen is soluble
(ii) those in which the antigen is bound to cells (red blood cells, bacterial cells, human cells) or to a surface (e.g... latex, nitrocellulose paper) |
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what types of tests can you use where antigen and antibody are in solution
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quantitative precipitation
ouchterlony analysis (rxn of identity, non-identity, partial identity) immunoelectrophoresis single radial immunodiffusion electroimmunodiffusion |
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what tests can be used where antigen and antibody are bound (not in solution)
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agglutination test
complement fixation immunofluorescence (direct / indirect0 enzyme linked immunosorbent assay (ELISA) western blot radioimmunoassay (liquid/solid phase) |
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what is direct coombs test used for
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The direct Coombs would be useful in detecting IgG sensitized red cells in an infant suspected of having hemolytic disease of the newborn.
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what is the indirect coombs test used for
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The indirect Coombs test would be used to detect IgG-associated antibody in the serum of the mother suspected of having been sensitized to the Rh antigen as from the Rh-positive cells of the fetus.
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what does it mean when you say "complement fixation"
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it represents the presence of antibody!!!!
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what is a paratope
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an antibody combining site for epitope located in the first domain of the Fab limb of the immunoglobulin)
|
|
|
why is it important for antibodies to be poly valent
|
For example, if you go from binding one Fab (paratope) to one antigenic determinant (epitope), the intrinsic affinity, to binding two paratopes of IgG, that functional affinity, that bivalency confers about a 1,000-fold increase in the strength of the antigen-antibody interaction. Thus by going from one to two binding sites we have an increase of 1,000 fold in functional affinity. If it were one to ten (where all IgM paratopes are binding epitopes the increase in functional affinity would be 10,000,000. Therefore, the bivalency or poly valency of antibody confers on it an enormous advantage in terms of binding antigen.
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what is avidity
|
This is the average of the functional affinities of antibody molecules.
It is important-to note that-the affinity is fundamental to an appreciation of antibody specificity |
|
|
what are the different types of antigen / antibody forces of attraction
|
(i) hydrogen binding (ii) electrostatic forces (iii) Van der Waals forces* (iv) hydrophobic interactions (these are the most important and account for about 50% of the binding energy between paratope and epitope
|
|
|
A broad division can be made with respect to the types of tests that we use to examine these antibody/antigen interactions:
|
(i) those in which antigen is soluble
(ii) those in which the antigen is bound to cells (red blood cells, bacterial cells, human cells) or to a surface (e.g... latex, nitrocellulose paper) |
|
|
what types of tests can you use where antigen and antibody are in solution
|
quantitative precipitation
ouchterlony analysis (rxn of identity, non-identity, partial identity) immunoelectrophoresis single radial immunodiffusion electroimmunodiffusion |
|
|
what tests can be used where antigen and antibody are bound (not in solution)
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agglutination test
complement fixation immunofluorescence (direct / indirect0 enzyme linked immunosorbent assay (ELISA) western blot radioimmunoassay (liquid/solid phase) |
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what is direct coombs test used for
|
The direct Coombs would be useful in detecting IgG sensitized red cells in an infant suspected of having hemolytic disease of the newborn.
|
|
|
what is the indirect coombs test used for
|
The indirect Coombs test would be used to detect IgG-associated antibody in the serum of the mother suspected of having been sensitized to the Rh antigen as from the Rh-positive cells of the fetus.
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what does it mean when you say "complement fixation"
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it represents the presence of antibody!!!!
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what does it mean when you say there is a "lack of complement fixation"
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the ABSENCE of complement antibody
complement remains in the system and is available for lysis of the added sensitivzed sheep RBCS |
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summary of the complement fixation test
what is POSITIVE test what is NEGATIVE test when do you see lysis when do you see no lysis |
Indicator System SRB Cs + Anti-SRB Cs + Complement Lysis of SRB Cs (Ag) (Ab) (C) Complement Fixation Test Positive Test Test Ag + Serum containing AB + C + IndicatorNo Lysis to test antigen system of SRB Cs Negative Test Test Ag + Serum lacking AB + C + Indicator Lysis of SRB Cs to test Antigen system
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talk about direct fluorescent antibody (DFA)
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you add labelled Ab and unlabelled Ag after they mix you have labelled Ab-Ag complex
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talk about indirect fluorescent antibody (IFA)
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you add unlabelled antibody and unlabelled antigen then you add fluorescent labelled anti-immunoglobulin to the mixture which labels the complex
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compare the DFA and IFA
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The indirect method has several advantages over the direct method: (i) Amplification: a lot of antibody binds to the immunoglobulin (anti-Ig). The labeled anti-Ig Ab then binds allowing for better resolution. (ii) Expense: only one probe is needed to detect any Ag. One labeled Ab is needed whereas; in the direct method a specific probe for each Ag is required. (iii) In the indirect method the patient's serum is used rather than the need for patient tissue.
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western blot tests possess what
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exquisite specificity
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The measure of binding strength (association constant) between a receptor (single binding site of an antibody) and a ligand
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Affinity:
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a molecule recognized by a receptor structure
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Ligand:
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The functional binding strength between bivalent antibody and a multivalent antigen. This differes from affinity in that it reflects the valency of the antigen-antibody interaction
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Avidity:
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the number of antigen binding sites on an antibody molecule; also the number of antigenic determinants on an immunogen
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Valence:
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