CHAPTER 6.2: AGGLUTINATION Flashcards
Technique in which molecules with a net charge are separated when an electric field is applied
ELECTROPHORESIS
Negative charged particles migrate to the
ANODE (+ Pole)
Positive charged particles migrate to
CATHODE (- Pole)
FACTORS THAT INFLUENCE RATE OF PROTEIN MIGRATION
• The bigger and the larger the size, it will be hard to migrate
SIZE AND SHAPE OF PROTEIN
• Used agarose gel and the amount of solvation has a great impact with regards to the rate of protein migration
AMOUNT OF SOLVATION
• alkaline pH
PH OF BUFFER: >8
• Room temperature
TEMPERATURE
• Protein will denature once it is exposed to high temperature
TEMPERATURE
• flow of ions goes toward the cathode and can impede movement of proteins toward the anode
ENDO-OSMOSIS
DIFFERENT TESTS FOR ELECTROPHORESIS
Laurell Technique (1960)
ROCKET IMMUNOELECTROPHORESIS
Radial immunodiffusion (RID) + electrophoresis
ROCKET IMMUNOELECTROPHORESIS
Single reactant moving in one dimension
ROCKET IMMUNOELECTROPHORESIS
Electrophoresis is used to facilitate migration of the antigen into the agar
ROCKET IMMUNOELECTROPHORESIS
End result: precipitin line that is conical in shape, resembling a rocket
ROCKET IMMUNOELECTROPHORESIS
The height of the rocket, measured from the well to the apex, is directly in proportion to the amount of antigen in the sample.
ROCKET IMMUNOELECTROPHORESIS
This technique has been used to quantitate immunoglobulins, using a buffer of pH 8.6
ROCKET IMMUNOELECTROPHORESIS
ROCKET IMMUNOELECTROPHORESIS Procedure:
1. Antigen is pushed through antibody containing gel under influence of an (?)
2. When they are equivalence, precipitation will occur forming a (?)
applied electric field
cone/ rocket shape band
• Ressler’s method
CROSSED IMMUNOELECTROPHORESIS
• Single reactant moving in 2 dimensions
CROSSED IMMUNOELECTROPHORESIS
CROSSED IMMUNOELECTROPHORESIS Procedure
1. Proteins are separated by (?)
2. Proteins are subjected to a 2nd electrophoresis where they will move through a (?) until rocket is formed (Ag-Ab reach equivalence)
electrophoresis
Ab-containing agarose
• Countercurrent electrophoresis
COUNTER IMMUNOELECTROPHORESIS
• Voltage Facilitated double immunodiffusions
COUNTER IMMUNOELECTROPHORESIS
• Double reactants moving in one dimension
COUNTER IMMUNOELECTROPHORESIS
COUNTER IMMUNOELECTROPHORESIS Use:
Identify bacterial, fungi or virus in fluids
COUNTER IMMUNOELECTROPHORESIS Procedure:
1. Ag and Ab are added to separate parallel wells cut out in an (?)
2. When an electric field is applied, the Ag will migrate to the (?) and Ab to the (?)
3. Zone of equivalence will form a (?)
agar gel
Anode; cathode
precipitate
• Grabar and Williams
CLASSIC IMMUNOELETROPHORESIS
• Double reactants moving in 2 dimensions
CLASSIC IMMUNOELETROPHORESIS
• Two-step process
CLASSIC IMMUNOELETROPHORESIS
• Used as a screening tool for the differentiation of many serum proteins, including the major classes of immunoglobulins.
CLASSIC IMMUNOELETROPHORESIS
• It is both a qualitative and a semiquantitative technique and has been used in clinical laboratories for the detection of myelomas, Waldenström’s macroglobulinemia, malignant lymphomas, and other lymphoproliferative disorders.
CLASSIC IMMUNOELETROPHORESIS
CLASSIC IMMUNOELETROPHORESIS Use:
Differentiate the Ig Class, identify abnormal proteins, myeloma proteins, Monitor purity of pharmaceutical products
CLASSIC IMMUNOELETROPHORESIS Procedure:
1. Ag is introduced in a well and an electric field is applied resulting in separation of proteins
2. Ab is introduced in a trough parallel to the separated protein
3. Ag-Ab complex form
CLASSIC IMMUNOELETROPHORESIS Procedure:
1. Ag is introduced in a well and an (?) is applied resulting in separation of proteins
2. Ab is introduced in a (?) parallel to the separated protein
3. (?) form
electric field
trough
Ag-Ab complex
CLASSIC IMMUNOELETROPHORESIS
Sequence:
• Cathode (+) to Anode (–)
- Albumin
- Alpha-1 globulin
- Alpha-2 globulin
- Beta globulin
- Gamma globulin
Immunoglobulin
Gamma globulin
STEPS IN AGGLUTINATION
published the first report about the ability of antibody to clump cells, based on observations of agglutination of bacterial cells by serum.
Gruber and Durham
This finding gave rise to the use of serology as a tool in the diagnosis of disease, and it also led to the discovery of the ABO blood groups (1902)
Gruber and Durham
Process by which (?) such as cell aggregate to form larger complexes when a (?) is present
particulate antigens (agglutinogen)
specific antibody (agglutinin)
Antigen-Antibody reaction
SENSITIZATION
Stabilization of agglutinogen + agglutinin
SENSITIZATION
Stabilization of antigen–antibody complexes with the binding together of multiple antigenic determinants.
SENSITIZATION
is affected by the nature of the antibody molecules themselves
SENSITIZATION
Best antibody for agglutination is IgM
SENSITIZATION
IgM
potential valence of 10 is over (?) more efficient in agglutination than is IgG with a valence of 2
700 times out of
Cross linking
LATTICE FORMATION
Representing the sum of interactions between antibody and multiple antigenic determinants on a particle (Avidity)
LATTICE FORMATION
There is visible agglutination
LATTICE FORMATION
FACTORS THAT AFFECT AGGLUTINATION
- Buffer pH Routine:
(close to physiological pH)
pH 7
Affects the zoning phenomenon
2.Relative concentration of Ag and Ab
• Abs will not detect determinants buried within the particle
- Location and concentration of Antigenic determinants of the particle
• More number of determinants, the higher the likelihood of cross bridging
- Location and concentration of Antigenic determinants of the particle
Non covalent interaction
- Electrostatic interactions between particles
• in the buffer plays an important role in agglutination
- Electrolyte concentration (ionic strength)
• Electrolytes reduce (?) that interfere with lattice formation
electrostatic charges
- Antibody isotope Best:
IgM
- Temperature
: Cold reacting (range 4-22oC)
: Warm reacting with optimum temperature at 37oC
IgM
IgG
- Time of incubation of coated particles with patient’s serum Incubation times ranges from
15-60 minutes
0
No agglutinates
Dark, turbid, homogenous
W+
Many tiny agglutinates, many free cells, may not be visible without microscope
Dark, turbid
1+
Many small agglutinates, many free cells (25% are agglutinated)
Turbid
2+
Many medium sized agglutinins, moderate number of free cells (50% are agglutinated)
Clear
3+
Several large agglutinates, few free cells (75% are agglutinated)
Clear
4+
One large solid agglutination, no free (100% are agglutinated)
Clear
MAJOR CATEGORIES OF AGGLUTINATION REACTIONS
It will not use any carrier particle
DIRECT/ ACTIVE AGGLUTINATION
Detecting the presence of antigen
DIRECT/ ACTIVE AGGLUTINATION
Occurs when antigens are found naturally on a particle
DIRECT/ ACTIVE AGGLUTINATION
Reaction is due to an Ag-Ab reaction where in the Ag is inherent native to the cell
Direct Immune
Example: ABO grouping (hemagglutination), Widal Test
• ABO antigens are found in the RBC
• Reagent: Antisera
Direct Immune
Aggregation of indicator rod blood cells are NOT due to AgAb reactions
Direct Non Immune
Example: Viral Hemagglutination test
Direct Non Immune
Direct non immune agglutination
VIRAL HEMAGGLUTINATION
Virus can stick to agglutinate RBC in the process
VIRAL HEMAGGLUTINATION
Rubella virus, dengue virus, influenza virus, mumps virus
VIRAL HEMAGGLUTINATION
Viral receptor: Peplomers
VIRAL HEMAGGLUTINATION
Competitive binding Assay Procedure:
1. Patient serum incubated with (?)
2. Viral particles will bind to the (?)
3. (?) added to reaction mixture
4.
Positive result: Negative result:
viral particles (Commercially available)
Fab region of Anti-viral Abs
Indicator RBCs
Inhibition or Absence of Agglutination; (Presence of Ab)
Agglutination
Reactions where Ag has been fixed or absorbed to a carrier/ inert particle
INDIRECT/ PASSIVE AGGLUTINATION
Detecting the presence of antibodies
INDIRECT/ PASSIVE AGGLUTINATION
Example: Antistreptolysin-O (ASTO)
INDIRECT/ PASSIVE AGGLUTINATION
Different passive carriers:
o Human RBCs
o Clay (Bentonite)
o Latex particles
o Colloidal gold
o Charcoal particles
Antibody is bound to the carrier
REVERSE PASSIVE AGGLUTINATION
The antibody must still be reactive and is joined in such a manner that the active sites are facing outward.
REVERSE PASSIVE AGGLUTINATION
Fluid is detected for the presence of Ag
REVERSE PASSIVE AGGLUTINATION
Example: CRP, Reverse agglutination test for Candida and Nisseria
REVERSE PASSIVE AGGLUTINATION
Patient sample (Ag) incubated with Ab in test kit
LATEX PARTICLE AGGLUTINATION INHIBITION
Complex will form if the patient sample contains the corresponding Ag and the Fab sites are no longer available for the Ag-coated latex particles
LATEX PARTICLE AGGLUTINATION INHIBITION
Reactions are based on competition between particulate and soluble antigens for limited antibody-combining sites, and a lack of agglutination is an indicator of a positive reaction
LATEX PARTICLE AGGLUTINATION INHIBITION
If the patient sample has no free hapten, the reagent antibody is able to combine with the carrier particles and produce a visible agglutination. In this case, however, agglutination is a negative reaction
LATEX PARTICLE AGGLUTINATION INHIBITION
Example: HCG/ pregnancy test
LATEX PARTICLE AGGLUTINATION INHIBITION
Agglutination inhibition.
(?) is added to the patient sample. If patient antigen is present, (?) results. When (?) are added, no agglutination occurs, which is a positive test. If no patient antigen is there, the (?), and agglutination results, which is a negative test.
Reagent antibody
antigen–antibody combination
antigen-coated latex particles
reagent antibody combines with latex particles
systems using bacteria as the inert particles to which antibody is attached
Coaglutination
Coaglutination
(?) is most frequently used, because it has a protein on its outer surface, called protein A, which naturally adsorbs the fragment crystallizable (FC) portion of antibody molecules.
Staphylococcus aureus
The active sites face outward and are capable of reacting with specific antigen
Coaglutination
particles nonspecifically bind the FC portion of immunoglobulin molecules. When reagent antibody is used, combination with patient antigen produces a visible agglutination reaction.
Staphylococcus aureus
detects non agglutinating antibody by means of coupling with a second antibody
ANTIGLOBULIN TEST
Detects IgG Ab bound to Ag on Red cells (in-vivo)
Direct Antiglobulin Test
Direct Antiglobulin Test Purpose:
• HDN investigation
• HTR investigation
• AIHA (Autoimmune Hemolytic Anemia)
• Drug induced Hemolytic Anemia
Direct Antiglobulin Test Example:
Direct Coomb’s test
• Detects presence of Abs in the serum that is still to be attached to an analyte
Indirect Antiglobulin Test
Indirect Antiglobulin Test Purpose:
o Crossmatching
o Ab determination
o Ab identification
o RBC Ag phenotyping
Example:
Indirect Coomb’s test
QUANTITATIVE AGGLUTINATION REACTION Best
Gold-inorganic colloidal particle
SPIA/ Sol Particle Immunoassay
Dye-organic colloidal particle
DIA/ Disperse Dye Immunoassay
Latex particle
IMPACT/ Immunoassay by Particle Counting
IMPACT/ Immunoassay by Particle Counting