L 6.1 Flashcards
(152 cards)
1
Q
Who discovered one of the earliest diagnostic tests for the detection of antibodies occurring in typhoid fever, brucellosis and tularemia
A
Widal and sicar
2
Q
What is an antigen?
A
Any substance that causes the body to make an immune response against that substance
3
Q
What does antigens activate
A
Lymphocytes
4
Q
What is an antibody?
A
A protein produced by the body’s immune system to target and neutralize specific antigens
5
Q
Production of antibodies
A
Immune system recognize an foreign body (antigen) release of antibodies
6
Q
What is an antigen-antibody reaction?
A
Interaction between antigen and antibody
7
Q
What is an immune complex?
A
Formed when antibody binds with antigen
8
Q
What is antigen-antibody reaction
A
Chemical interaction of antibodies (from B cells: WBC) and sntigen during immune reaction
9
Q
molecule formed when antibody
binds with antigen
A
Immune complex
10
Q
What can happen if immune complexes accumulate in the body?
A
May lead to immune complex disease
11
Q
formation of antigen-antibody complex as a normal part of the body?s immune response, especially when fighting against infection
A
Immune complex
12
Q
Explain the process if accumulation of immune complex
A
Immune complex formed in the blood are eliminated by immune cells.
If immune complex are not completely removed it will accumulate inthe the issues leading to immune complex disease
13
Q
Reasons for incomplete removal of immune complexes
A
1 excess immune complex
2 high levels of antigen in infested individual
3 issue with eliminating immune complexes
14
Q
What is a paratope?
A
Part of antibody that combines with antigen
15
Q
Where is paratrope located
A
Ab (variable porttion) portion of the antibody
16
Q
What is an epitope?
A
Part of antigen that combines with antibody during an immune response
17
Q
What is the antigenic determinant called
A
Epitope
18
Q
Antigen-antibody reaction process
A
- Recognition
2 Antibody production
3 Abs-Ags Binding
4 Elimination
5 Memory
19
Q
Explain the elimination of cells
A
The immune system recognize bound antigens (immune complex) as foreign and work to eliminate them thru:
1 phagocytosis
2 series of reaction that leads to the destruction of pathogens/antigen
20
Q
Give the processes of elimination
A
- Phagocytosis
2 series of reactions that lead to destruction of pathogen/antigen
21
Q
Explain the process of memory
A
B lymphocytes become b cells. These cells are responsible for remembering specific antigens, so if these antigens are encountered again, production of antibodies are immediate
22
Q
Origin of memory cells
A
B lymphocytes/cells
23
Q
What is agglutination?
A
Clumping that results from the interaction between an antibody and a particulate antigen.
24
Q
What examples of particulate antigens can cause agglutination?
A
Cells (bacteria, yeast cells, RBCs), inert particles (platelets, charcoal particles, gelatin).
25
What is a common use of agglutination in the lab?
Blood the typing
* To detect the presence of a specific antigen or antibody in px?s blood
26
How does blood typing utilize agglutination?
Agglutination indicates a positive reaction, helping to identify the blood type.
27
What year was serum antibody was found to react with bacterial cells
1896
28
Who discovered serum antibody to react with bacterial cells
Gruber and burham
29
What did gruber and durham discover
serum antibody was found to react with bacterial cells
30
When was the earliest diagnostic tests for the detection of antibodies occurring in typhoid fever, brucellosis and tularemia discovered
1896
31
who discovered one of the earliest diagnostic tests for the detection of antibodies occurring in typhoid fever, brucellosis and tularemia
widal and sicard
32
what was discovered by widal and sicard in 1896
one of the earliest diagnostic tests for the detection of specific antibodies occurring in tularemia, brucellosis and typhoid fever
33
In the test discovered by widal and sicard specific antibodies of these diseases are detected
1. typhoid fever
2. burcellosis
3. tularemia
34
What are agglutinins
antibodies that reacts with antigen on a surface of a particle
35
example surfaces where Abs-Ags sensitized
1. RBCs
2. bacteria
3. inert particles (latex particles)
36
helps in the detection of pathogen, antigens and blood group antigens
Agglutinin
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What are agglutinogens
antigens on the surface of particles that react with the agglutinin
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Agglutinogen is also called
isoantigen
39
responsible for determining our blood type within the ABO blood group
agglutinogen
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Steps in Agglutination
1 Sensitization
2 Lattice Formation
41
What is agglutination?
is a two-step process (sensitization + lattice formation) resulting in a formation of a stable lattice network
42
difference between agglutination and precipitation
precipitation - soluble
* antigen and antibodies soluble in a solution
agglutination - insoluble
* antibody is made to react with a particulate antigen to form insoluble agglutinate
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attachment of a specific antibody to an antigen in a single antigenic determinant on a particulate surface
sensitization
44
is clumping visible during sensitization
NO
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What happens during sensitization
antibodies only attach to their specific antigenic determinant (epitope) on the RBC membrane.
* No formation lattice for visible agglutination
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Difference: Sensitization vs. Latiice Formation
Sensitization - no visible agglutination, reversible, rapid, Abs attachment to single antigenic determinant, no reaction present,
Lattice formation - visible agglutination, irreversible, slow, establishment of cross-linking between sensitized particles, crosslinking influenced by zeta potential
47
Sensitization or Lattice: no visible agglutination
Sensitization
48
Sensitization or Lattice: reversible
Sensitization
49
Sensitization or Lattice: rapid
Sensitization
50
Sensitization or Lattice: Abs attachment to single antigenic determinant
Sensitization
51
Sensitization or Lattice: no reaction present
Sensitization
52
Sensitization or Lattice: visible agglutination
Lattice
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Sensitization or Lattice: affected by the nature of antibody molecule
Sensitization and Lattice
54
Antibody that works best at agglutination because of its several binding site
IgM
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Sensitization or Lattice: irreversible
Lattice
56
Sensitization or Lattice: crosslinking influenced by zeta potential
Lattice
57
Sensitization or Lattice: establishment of cross-linking between sensitized particles
Lattice
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What does affinity vs. avidity mean
used to describe strength and stability of the binding interaction between antigen and antibody in the immune response
59
What does affinity refer to?
Strength of a single interaction
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measures how tightly an antibody binds to a specific antigen
affinity
61
What does avidity refer to?
Total strength of a multivalent interaction
62
What influences avidity?
Divalency of the antibody and multivalency of the antigen
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Difference: Affinity vs. Avidity
Affinity - strength of binding between SINGLE antigen binding site on an antibody
Avidity - OVERALL strength of the binding interaction between MULTIPLE antigen binding sites on a single antibody molecule. MULTIPLE epitopes
64
avidity is influenced by:
1. divalency of antibody (number of antigen binding sites)
2. multivalency of the antigen (number of epitopes) -antigenic determinant
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What is lattice formation?
Sum of interactions between antibody and multiple antigenic determinants
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What conditions affect lattice formation?
Environmental conditions and relative concentrations of antigen and antibody present in the sample
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Why can't IgG often bridge the distance between particles?
Smaller in size, restricted flexibility at hinge region, preventing multivalent binding
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What is usually required for a visible reaction to be observed with IgG antibodies?
Enhancement techniques
69
Why are IgM considered strong agglutinins?
Diameter of ~35nm
70
Can visible clumping be seen immediately with IgM without addition of any enhancement techniques?
Yes
71
What is sensitization in the context of agglutination?
Antigen-antibody binding, no visible agglutination
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What is lattice formation in the context of agglutination?
Crosslinks formed, causing visible agglutination
73
What is the term for an abundance of antibodies saturating antigen binding sites?
Prozone
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What can lead to false negative results in antigen-antibody testing?
Prozone (Abs excess) and Postzone (Ags excess)
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the optimal concentration of antigens and antibodies
zone of equivalence
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Causes for lack of Reactivity
1. Antigen-Antibody concentrations
2. Poor function of Antibody and Antigen
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What is the term for excess antigen relative to antibodies in a sample?
Postzone
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Reasons for Abnormality in Antigen
1. antigenic sites lies deep within the surface coat of the particle
2. antigenic sites are not easily accessible
3. no cross-linking formation happens
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Reasons for Abnormalities in Antibodies
1. movement of the hinge region is limited
2. structural abnormality
3. poor function of antibody - leading to a no-to-weak reaction
80
Factors that influence the Abs-Ags reaction
1. viscosity
2. pH
3. Temperature
4. Ionic Strength
5. Abs-Ags concentration
6. Motion
7. Time of incubation
8. Class of antibody
9. RBCs zeta potential
81
what is added when the solution is viscous to enhance agglutination
Dextran and Polyethylene glycol (PEG)
82
What is the purpose of the addition of dextran and PEG in viscous solutions
removes/reduces water for hydration present around cell to allow closer proximity for Abs-Ags interaction
83
optimal ph fo Abs-Ags interaction
ideal range: 6.5 - 7.5
optimum: 7.0
84
How does temperature influence agglutination
temperature affects the binding strength, speed and rate of reaction
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optimum temperature for IgM
4-27C
86
cold reacting antibodies
IgM
87
Optimum temperature for IgG
30-37C
88
warm reacting antibodies
IgG
89
How does ionic strength influence agglutination
decreased/low ionic strength enhances/ increase rate of association
90
What is the optimum concentration of Antigen to antibody
zone of equivalence
91
motions that enhances agglutination
stirring, shaking and centrifugation
92
How does time of incubation affect agglutination in:
Slide test
Tube test
Prolonged:
Slide - False (+)
Test tube - False (-) due to disassociation of complex
shortened = no-to-weak reaction
93
What class of antibody is an efficient agglutinator due to its pentamer structure?
IgM
94
what causes zeta potential in RBCs
difference in charge density of the inner and outer layers of the ionic cloud around the RBCs
95
What class of antibody is an efficient precipitator because it can only reach antigenic sites up to 14nm?
IgG
96
What keeps RBCs about 25nm apart in a solution?
Zeta potential
97
why is IgM an efficient agglutinator than IgG
Because diameter matters. IgM (35nm) and IgG (14nm).
* Due to zeta potential, RBCS are forced to be separated 25nm apart. Antibodies need to reach antigens to create complex. Therefore, IgM is an efficient agglutinator because its diameter is greater than >25nm
98
how does colloidal diluents enhance lattice formation
reduces water of hydration around RBCs to allow closer proximity
99
What reduces the water of hydration around RBCs to allow them to come into closer proximity for antibodies to join them together?
Colloidal diluents
100
examples of colloidal diluents
1. bovine albumin
2. polybrene
3. polyethylene glycol
4. protamin
5. polyvinylpyrrolidone
101
What type of enzyme reduces the surface charge on RBCs by cleaving chemical groups and decreasing hydration?
Proteolytic enzymes
102
How does proteolytic enzymes enhance lattice formation
1. reduce surface charge of RBCs through cleavage of chemical groups
2. reduce water for hydration
103
examples of proteolytic enzymes and their origin
1. papain - papaya
2. bromelin - pineapple
3. trypsin - pig intestines
4. ficin - figs
104
What reagent is used to bridge the gap between sensitized cells in tests like the Coombs Test?
AHG reagent
105
What test is used to detect antibodies that act against the RBC surface and indicates hemolytic anemia?
Coombs Test
106
Coomb's Test: cross-matching
indirect
107
Coomb's Test: diagnosis of hemolytic anemia
direct
108
Coomb's Test: Patient serum
Indirect
109
Indirect coomb's test procedure
1. px serum
2. washing of donor rbc with NSS
3. combination of px serum and donor rbc (major cross-matching)
4. incubation @ 37C for 15-30 mins
5. AHG reagent
110
interpretation of (+) agglutination in indirect coomb's test
antibodies in px reacts with antigens present on rbc surface of donor cells (incompatible)
111
Coomb's Test: detects the presence of anti-Rh(+) in Rh(-) mothers that birthed Rh(+) child
Indirect
112
What provides a physical means to increase cell-cell contact and heighten agglutination by overcoming the natural repulsive effect of RBCs?
Agitation and centrifugation
113
interpretation of (+) agglutination in direct coomb's test
cells were coated in vivo with IgG
114
How does agitation and centrifugation enhance lattice formation
provides the physical force to override zeta potential between cells [overcoming natural repulsive effects of rbcs] to allow increased ag-ab interaction (specially igg)
115
Coomb's Test: Patient RBC
Direct
116
Process of Direct Coomb's Test
1. washing of px rbc with NSS
2. decant supernatant
3. addition of AHG reagent
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When does direct immune agglutination occur?
When antigens are naturally found on a particle
118
direct immune agglutination examples
1. abo blood typing
2. widal test
119
Major categories of agglutination reaction
1. direct immune
2. direct non-immune
3. indirect/passive
120
rapid screening test to detect presence of typhoid fever
widal test
121
What does widal test detect/determine
detects ANTIBODIES produces by the body against salmonella to determine presence/previous infection of typhoid fever
122
antigens used in widal's test
salmonella O (somatic)
salmonella H (flagellar)
123
How is ABO blood typing done (methods)
1. slide methods
2. test tube
3. gel method
124
when does hemaggulation occur
hemaggulation reaction involves RBCs
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explain why is tube test more reliable and sensitive during abo typing
because it test tube was centrifuged
126
differentiate: forward and reverse typing
forward typing: indicates presence/absence of antigens on px RBCs
antigen: px RBC
antibody: Anti-sera A(blue) B(yellow)
Results: A and B antigens
Reverse typing: indicates presence/absence of antibodies on px serum (Anti- A and Anti-B)
antigen: known A1 and B1 cells
antibodies: px serum
Results: Anti- A and Anti-B
127
Grade: many small aggregates with turbid background
1+
128
small-medium aggregates with clear background
2+
129
several medium-large aggregates
3+
130
one large clump/button
4+
131
What is non-immune agglutination?
Agglutination not involving an immune response
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what causes the agglutination in direct non-immune?
BASTA not antibodies
MAYBE:
1. viral
2. pytohemagglutination (lectin)
133
What viruses cause viral hemagglutination?
Influenza, mumps, measles, rubella, dengue
134
true or false: lectin hemagglutinins have the ability to cause agglutination w/o presence of ag-ab interaction
TRUE
135
true or false: viral hemagglutinins have the ability to cause agglutination w/o presence of ag-ab interaction
TRUE
136
What is phytohaemagglutinin (PHA)?
Plant-derived protein that agglutinates RBCs
137
true or false: pytohemagglutinin does not have the ability to cause agglutination w/o presence of ag-ab interaction
FALSE
138
specific origin of pytohemagglutinin (lectin)
legumes
139
proteins related to pytohemagglutinins
1. leucoagglutinin (PHA-L)
2. PHA-E
140
What is an example of lecitins? and their origin
Anti-H - Ulex europaeus
lecitin - dolichos biflorus
141
What does the Dolichos biflorus lectin agglutinate?
A1 cells
142
What does the Ulex europaeus lectin agglutinate?
Group O cells
143
What is required for indirect or passive agglutination?
Carrier particles
144
indirect or passive agglutination antigen/antibodies are attached to ?
1. biological carrier - rbc
2. inert carrier - latex particles, bentonite, charcoal or polystyrene particles
145
What are examples of biological and inert carriers used in indirect or passive agglutination?
RBCs, latex, bentonite, charcoal, polystyrene particles
146
antibodies are attached to particulate carrier
reverse passive agglutination
147
In passive agglutination, what is attached to the particulate carriers?
Antigens
148
In reverse passive agglutination, what is attached to particulate carriers?
Antibodies
149
What is the Coombs test also known as?
Antiglobulin technique
150
what is the outcome when abs/ags reacts with particulate carriers?
agglutination
151
antigens are attached or coated onto the particulate antigen
passive agglutination
152
What is used in the Coombs test to bridge the gap between sensitized cells?
Anti-human globulin
