Podcast
Questions and Answers
In agglutination reactions, what type of substance aggregates when a specific antibody is present?
In agglutination reactions, what type of substance aggregates when a specific antibody is present?
- Hormones
- Lipids
- Particularly cellular antigens (correct)
- Enzymes
Which class of antibodies is typically MOST efficient at causing agglutination reactions?
Which class of antibodies is typically MOST efficient at causing agglutination reactions?
- IgG
- IgM (correct)
- IgA
- IgE
What is the first step involved in agglutination reactions?
What is the first step involved in agglutination reactions?
- Sensitization (correct)
- Neutralization
- Lattice formation
- Precipitation
What process occurs during the 'lattice formation' stage of agglutination?
What process occurs during the 'lattice formation' stage of agglutination?
In agglutination grading, what is indicated by a '4+' reaction?
In agglutination grading, what is indicated by a '4+' reaction?
In agglutination grading, what does a weak positive reaction (± to 1+) typically indicate?
In agglutination grading, what does a weak positive reaction (± to 1+) typically indicate?
Which of the following agglutination types involves antigens that are naturally found on the surface of a particle?
Which of the following agglutination types involves antigens that are naturally found on the surface of a particle?
What is the primary component involved in hemagglutination assays?
What is the primary component involved in hemagglutination assays?
In bacterial agglutination, which of the following components contains surface antigens leading to agglutination?
In bacterial agglutination, which of the following components contains surface antigens leading to agglutination?
What is the primary advantage of particle immunoassays over traditional agglutination methods?
What is the primary advantage of particle immunoassays over traditional agglutination methods?
In gelatin particle agglutination, what is the primary advantage over using red blood cells?
In gelatin particle agglutination, what is the primary advantage over using red blood cells?
What component is attached to a carrier particle in passive or indirect agglutination?
What component is attached to a carrier particle in passive or indirect agglutination?
The Rapid Plasma Reagin (RPR) test for syphilis is an example of which type of agglutination?
The Rapid Plasma Reagin (RPR) test for syphilis is an example of which type of agglutination?
In reverse passive agglutination, what is attached to the carrier particle?
In reverse passive agglutination, what is attached to the carrier particle?
The CRP measurement is an example of which type of agglutination assay?
The CRP measurement is an example of which type of agglutination assay?
In coagglutination, what component serves as the inert particle to which antibodies are first attached?
In coagglutination, what component serves as the inert particle to which antibodies are first attached?
Which bacterium is most commonly used in coagglutination assays due to its protein A affinity for IgG?
Which bacterium is most commonly used in coagglutination assays due to its protein A affinity for IgG?
In agglutination inhibition, what does the lack of agglutination indicate?
In agglutination inhibition, what does the lack of agglutination indicate?
Which type of agglutination test is used in urine HCG testing?
Which type of agglutination test is used in urine HCG testing?
What is the purpose of Anti-Human Globulin (AHG) in the Coomb's test?
What is the purpose of Anti-Human Globulin (AHG) in the Coomb's test?
The Direct Antiglobulin Test (DAT) detects which of the following?
The Direct Antiglobulin Test (DAT) detects which of the following?
What is one of the primary purposes of the Indirect Antiglobulin Test (IAT)?
What is one of the primary purposes of the Indirect Antiglobulin Test (IAT)?
Which of the following describes what the Indirect Antiglobulin Test (IAT) detects?
Which of the following describes what the Indirect Antiglobulin Test (IAT) detects?
What does polyspecific AHG reagent contain?
What does polyspecific AHG reagent contain?
If O check cells added to a negative AHG test result in agglutination, what does this indicate?
If O check cells added to a negative AHG test result in agglutination, what does this indicate?
What could cause a false negative result in an AHG test?
What could cause a false negative result in an AHG test?
Why is proper washing of cells important in AHG testing?
Why is proper washing of cells important in AHG testing?
What causes the false appearance of clumping in pseudoagglutination?
What causes the false appearance of clumping in pseudoagglutination?
What technique is used to correct pseudoagglutination?
What technique is used to correct pseudoagglutination?
Flashcards
Agglutination Antigen
Agglutination Antigen
An antigen that is particulate or cellular in nature.
Agglutinins
Agglutinins
Antibodies that produce agglutination reactions.
Agglutinogen
Agglutinogen
Antigens that stimulate agglutination.
Sensitization
Sensitization
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Lattice Formation
Lattice Formation
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Direct Agglutination
Direct Agglutination
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Hemagglutination (HAT)
Hemagglutination (HAT)
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Bacterial Agglutination
Bacterial Agglutination
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Particle Immunoassay
Particle Immunoassay
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Passive/Indirect Agglutination
Passive/Indirect Agglutination
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Reverse Passive Agglutination
Reverse Passive Agglutination
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Coagglutination
Coagglutination
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Agglutination Inhibition
Agglutination Inhibition
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Antiglobulin Test (Coomb's)
Antiglobulin Test (Coomb's)
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Direct Antiglobulin Test (DAT)
Direct Antiglobulin Test (DAT)
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Indirect Antiglobulin Test (IAT)
Indirect Antiglobulin Test (IAT)
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Polyspecific AHG Reagent
Polyspecific AHG Reagent
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Monospecific AHG Reagent
Monospecific AHG Reagent
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Pseudoagglutination
Pseudoagglutination
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What causes false agglutination?
What causes false agglutination?
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Study Notes
Agglutination Reactions
- Agglutination involves antigen, particularly cellular in nature (erythrocytes, bacteria, or latex), aggregating when a specific antibody (IgM, IgG) is present
- Agglutinins are antibodies that produce agglutination reactions; IgM is the most effective
- Agglutinogen refers to antigens that produce agglutination reactions
The Agglutination Process
- Agglutination involves a two-step process:
- Sensitization/ Initial Binding: physical attachment of antibody molecules to antigens on an erythrocyte membrane
- Lattice Formation: establishment of cross-links between sensitized particles to form visible aggregates
Grading of Agglutination Reactions
- Negative/ Mixed Field: No aggregates
- Weak (±): Few isolated aggregates; mostly free-floating cells
- 1+: Tiny aggregates barely visible; many free erythrocytes make the supernatant turbid and reddish
- 2+: Some aggregates that are just visible, many free erythrocytes, turbid and reddish supernatant
- 3+: Medium-sized aggregates; some free erythrocytes make the supernatant clear
- 4+: Several large aggregates; some free erythrocytes make the supernatant clear
- 4+: All erythrocytes combined into one solid aggregate; clear supernatant
Types of Agglutination
- Direct Agglutination
- Indirect Agglutination/Passive
- Reverse Passive Agglutination
- Coagglutination
- Agglutination Inhibition Reaction
- Anti-Human Globulin Testing (AHG)
Direct Agglutination
- Antigens are naturally found on the surface of the particle
- Includes Hemagglutination and Bacterial agglutination
Hemagglutination (HAT)
- Agglutination occurs in red blood cells, which contain surface antigens
- Includes ABO, Rh Typing, Infectious mononucleosis tests (Anti-i); Paul Bunnel Screening Test; Davidsohn Differential Test and Primary Atypical Pneumonia (Anti-I)
Bacterial Agglutination
- Agglutination occurs in bacterial cells, which contain surface antigens
- Includes Widal test and Weil-Felix test
Other Types of Agglutination
-
Particle Immunoassay
- Utilizes solid-phase particles to bind soluble antigens to form visible conjugates that simplifies since it does not require separation
-
Gelatin Particle Agglutination
- Solid phase uses gelatin particles, which has no antigenicity and free from problems associated with heterophile antibodies
Passive/Indirect Agglutination
- Soluble antigen is attached to a carrier particle (latex, charcoal, bentonite, or RBCs)
- Agglutination happens only when an antibody is present
- Example: Rapid Plasma Reagin Test (RPR)
Reverse Passive Agglutination
- Antibody attached to the carrier particle
- Agglutination happens only when a patient antigen is present
- Example: CRP measurement
Coagglutination
- Utilizes bacteria as the inert particles to which antibodies are attached
- S. aureus is the most frequently used
- Outer membrane has protein A with high affinity to Fc portion of IgG1, IgG2 and IgG4
Agglutination Inhibition
- Lack of agglutination is an indicator of a positive reaction
- (+) result = NO agglutination
- (-) result = WITH agglutination
- Examples: Urine HCG test, Test for Rubella antibodies, Test for Influenza antibodies
Antiglobulin-Mediated Agglutination (Coomb's Test)
- Detects non-agglutinating antibody by coupling with a second antibody like Anti-human Globulin/ AHG
- AHG spans the distance between two IgG antibodies
- Consists of Direct Antiglobulin Test (DAT) and Indirect Antiglobulin Test (IAT)
Direct Antiglobulin Test (DAT)
- Detects IN VIVO sensitization of RBC
- Used in the Investigation of HDFN, Investigation of HTR, Diagnosis of AIHA and Diagnosis of DIHA
Indirect Antiglobulin Test (IAT)
- Detects IN VITRO sensitization of RBC
- Involves incubation of red cells with antibodies first before adding AHG reagent
- Used for Crossmatching, Antibody detection, Antibody identification and RBC antigen phenotyping
Types of AHG Reagent
- Polyspecific AHG: anti-IgG and anti C3d
- Multiple specificity, prepared with conventional techniques, and derived from rabbits
- Monospecific AHG: anti-IgG or anti-C3d
- Derived from mouse monoclonal production
- O Check Cells
- Group O RBCs sensitized with IgG
- Added to negative AHG tests to validate negative results with agglutination (VALID)
- False NEG = NO Agglutination (INVALID)
Must Know AHG
- Improper washing of cells can cause a FALSE NEGATIVE where unbound globulin neutralizes AHG reagent
- Wash cells at least 3 times; wash cord blood 6-8 times when contaminated with Wharton's jelly
- Confirm all negative results with check cells or Coomb's cells!
Pseudoagglutination
- Presents as a false appearance of clumping caused by rouleaux formation and plasma cell dyscrasias when using dextran
- Remedy: Saline replacement to avoid false negative from saline dilution effect
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Description
Explore agglutination reactions, where antigens aggregate in the presence of specific antibodies. Learn about the two-step process involving sensitization and lattice formation. Understand how to grade these reactions, from negative to 2+ based on aggregate visibility and supernatant characteristics.
