Antigen-Antibody Reactions Flashcards
•The interactions between antigens and antibodies
Antigen–Antibody reactions
Antigen–Antibody reactions are highly ____, and an antigen reacts only with ___.
highly specific, and reacts only with antibodies produced by itself or with closely related antigens.
Antibodies recognize ___ on antigens.
molecular shapes (epitopes)
the better the fit of the epitope (in terms of geometry and chemical character) to the antibody combining site, the more favorable the interactions that will be formed between the antibody and antigen
High affinity of antibody for antigen
Specificity of antigen – antibody reaction
each antibody binds to a specific antigen; an interaction similar to lock and key
Immune complex
Ag + Ab → Ag-Ab complex.
molecule formed from the binding of multiple antigens to antibodies.
Immune complex
The molecular shape on an antigen that is recognized by antibodies is called ____.
Epitope (Antigenic Determinant)
The part of the antibody that binds to the antigen’s epitope is called ____
Paratope
The specificity of antigen-antibody binding is similar to a ____.
Lock and Key
The molecule formed when antigens and antibodies bind together is called ____.
Immune Complex (Ag-Ab Complex)
The three factors affecting the binding force of an antigen-antibody reaction are ____.
Closeness, Non-Covalent Bonds, Affinity
The types of bonds involved in antigen-antibody interactions are
Hydrogen Bonds, Electrostatic Bonds, Van der Waals Forces, Hydrophobic Bonds
The strength of the reaction between a single antigenic determinant and a single antibody site is called ____.
Affinity
The total binding strength between multiple antigenic determinants and multiple antibody sites is called ____.
Avidity
The phenomenon where an antibody reacts with an antigen similar to the original antigen is called ____.
Cross Reaction
One major application of antigen-antibody reactions in medicine is ____.
Blood Group Determination for Transfusions
The antigen-antibody reaction used to detect the presence or absence of a protein in serum is called ____.
Immunoassay
The two major types of antigen-antibody reactions are ____
Agglutination and Precipitation
The binding strength of an antigen-antibody reaction is influenced by ____.
Affinity and Avidity
A clinical application of antigen-antibody reactions to detect exposure to infectious agents is called ____.
Serological Testing
Properties of Antigen-Antibody Reaction
- Antibody affinity
- Antibody avidity
- Cross reaction
Application of Ag-Ab Reaction
Blood Typing
Infection Detection
Immunoassays
Protein Testing
Immunodeficiency Diagnosis
Types of Ag-Ab Reactions
AGGLUTINATION
PRECIPITATION
COMPLEMENT FIXATION
ELISA
IMMUNOFLUORESCENCE
RADIOIMMUNOASSAY
IMMUNOFIXATION
IMMUNOELECTROPHORESIS
The clumping of particulate antigens when mixed with their specific antibodies is called ____.
Agglutination
The antibodies responsible for causing agglutination are called
Agglutinins
The particulate antigens that are aggregated during agglutination are called ____.
Agglutinogens
The rapid method used to determine the presence of agglutinating antibodies is called ____.
Slide Agglutination
The test used for blood grouping and crossmatching is ___
Slide Agglutination
The visible sign of a positive slide agglutination test is ___
Granulation
The standard method for the quantitative estimation of antibodies is called ____.
Tube Agglutination
In tube agglutination, the serum containing antibodies is diluted using ____
Saline
The tube showing the highest level of agglutination in tube agglutination is referred to as ____.
Titer
Tube agglutination is used for the serological diagnosis of ____, ____, and ____.
Typhoid, Brucellosis, Typhus Fever
The process in which particulate antigens bind to antibodies, forming visible clumps is called ____.
Agglutination
The formation of a lattice structure where antigens bind with Fab sites of two antibodies is called ____.
Lattice Formation
The type of agglutination commonly used in blood banks is called ____.
Direct Agglutination
The test where RBCs are treated with tannic acid to allow adsorption of protein antigens is called ____.
Passive Hemagglutination
The test where antigens are attached to latex particles for detection is called ____.
Passive Latex Agglutination
The test where a patient’s serum antigen reacts with a limited amount of antibody reagent is called ____.
Agglutination Inhibition
A positive agglutination inhibition test is indicated by ____.
No Agglutination
An example of an agglutination inhibition test used for detecting rubella is ____.
Hemagglutination Inhibition Test
The reaction where a soluble antigen combines with its antibody to form an insoluble complex is called ____
Precipitation
The antibody responsible for precipitation reactions is called
Precipitin
The test where both antigen and antibody diffuse in a gel to form visible precipitin lines is called ____.
Double Diffusion (Ouchterlony)
The test where only the antigen diffuses into a gel containing antibody is called ____.
Single Diffusion (Radial Immunodiffusion)
The technique that separates proteins in a gel before antigen-antibody interaction is ____.
Immunoelectrophoresis
The test that involves the lysis of RBCs or bacteria using serum components is called ____.
Complement Fixation
A positive complement fixation test is indicated by ____
No Hemolysis
A negative complement fixation test is indicated by ____.
Hemolysis
A major limitation of complement fixation tests is that they are only used for detecting ____
IgM Antibodies
Complement fixation tests require that serum must be ____
Heat Inactivated
The indicator used in complement fixation tests is ____
Sheep RBCs Coated with Hemolysin
The immunoassay that uses an enzyme-linked antibody for detection is called ____.
Enzyme-Linked Immunosorbent Assay (ELISA)
The technique where an antibody-coated surface captures an antigen, followed by an enzyme-labeled antibody, is called the
Sandwich Technique
In ELISA, improper washing between steps can lead to ____
False Positive Results
In ELISA, absorbance is directly proportional to ____
Antigen Concentration
ELISA is commonly used for detecting ____, ____, and ____
HIV, Hepatitis Antigens and Antibodies, Pregnancy (Serum HCG)
The immunoassay technique that uses fluorescent dyes to visualize antigen-antibody reactions is called ____.
Immunofluorescence
The property of absorbing light at one wavelength and emitting light at another is called ____.
Fluorescence
In ____, a fluorescein-labeled antibody is directly applied to patient tissue and observed under a fluorescent microscope.
Direct Immunofluorescence
In ____, patient serum is first incubated with a reagent antigen, then treated with a fluorescein-labeled antiglobulin.
Indirect Immunofluorescence (IIF)
Examples of indirect immunofluorescence tests include ____
Antinuclear Antibody (ANA) Test, Fluorescent Treponemal Antibody Test (FTA-Abs)
The highly sensitive immunoassay that uses radioactively labeled antigens or antibodies is called ____.
Radioimmunoassay (RIA)
Radioimmunoassay follows a ____, where patient antigen competes with labeled antigen for antibody binding.
Competitive Binding Assay
In RIA, if the radioactive count is low, it indicates that the concentration of the patient’s unlabeled antigen is
High
The instrument used to measure radioactivity in RIA is called a ____.
Gamma Counter
Radioimmunoassay (RIA) is used to detect ____.
Antigens or Antibodies
