ImmunoSero Lab (Midterm - Ag & Ab Reaction) Flashcards
Specificity of antigen-antibody reactions
highly specific
reacts only with antibodies produced by itself or with closely related antigens
antigens
Recognize molecular shapes (epitopes) on antigens
Antibodies
The ____________ fit of the epitope, the more ____________ the interactions will be formed between the antibody and antigen and the ____________ the affinity of the antibody for antigen.
better fit
more favourable interactions
higher affinity
Salient features of Ag-Ab Reaction
- Specificity of antigen-antibody
- Immune complex
- Binding site of antigen-antibody reaction
- Binding force of antigen-antibody reaction
Salient feature of Ag-Ab Reaction:
Each antibody binds to a specific antigen where its interaction is similar to lock and key.
Specificity of antignen-antibody
Salient feature of Ag-Ab Reaction:
- Ag + Ab —> Ag-Ab complex
- Molecule formed from the binding of multiple
antigens to antibodies - The bound antigen and antibody act as a
unitary object, effectively an antigen of its
own with a specific epitope
Immune complex
Salient feature of Ag-Ab Reaction:
In Ag-Ab reaction, the Ab attaches with the
Antigen
Binding site of antigen-antibody reaction
The part of the antigen which combines with the antibody which is also known as antigenic determinant
epitope
The epitope is recognized by the immune system, specifically by:
Antibodies
B cells
T cells
The part of the antibody that recognized the epitope
Paratope
3 Factors (Binding force of Ag-Ab reaction)
- Closeness between Ag and Ab
- Affinity of antibody
- Non-covalent bonds of intermolecular forces
When antigen and antibody are ____________ the strength of binding is great; when they are ____________ binding strength is low.
A) apart; closely fit
B) closely fit; apart
B) closely fit; apart
These bonds hold the antigen to the antibody combining site
Noncovalent bonds
These include:
Hydrogen bonds
Electrostatic bonds
Van der Waals forces
Hydrophobic bonds
Strength of the reaction between a single antigenic determinant and a single combining site on the antibody
Affinity
Properties of antigen-antibody reactions
- Antibody affinity
- Antibody avidity
- Cross Reaction
Measure of the binding strength at a single binding site
affinity
Measure of total or overall strength
avidity
Application of Ag-Ab reaction:
(DDD ST)
- Determination of blood groups for transfusion
- Determining the characteristics of certain immunodeficiency disease
- Development of immunoassays for the quantification of various substances
- Serological exposure to infectious agents
- To detect the presence or absence of protein in serum
Types of Ag-Ab Reactions:
APICE IRI
- Agglutination
- Precipitation
- Immunofluorescence
- Complement fixation
- ELISA
- Immunofixation
- Radioimmunoassay
- Immunoelectrophoresis
A type of reaction when a particular Ag is mixed with its Ab’s in the presence of electrolytes at a suitable temperature and pH; the particles are clumped or agglutinated
Agglutination
The Ab of the serum causes the cellular Ag’s to form clumps and these are called
agglutinins
The participate antigens that are aggregated
agglutinogens
Rapid method to determine the presence of agglutinating antibodies
Slide agglutination
This is a standard method for quantitative estimation of Ab
Tube agglutination
This is the test used for blood grouping and cross matching
slide agglutination
This indicates that test in slide agglutination is positive
granulation
The tube showing highest agglutination
Titer
Employed for the serological diagnosis of Typhoid, Brucellosis, Typhus fever
Tube agglutination