Basic Serological Concepts and Principles Flashcards

1
Q

scientific study of serum and other bodily fluids
measures the amount of Ag or Ab in serum

useful in:
- diagnosing a disease
- efficacy of vaccine
- monitoring therapy

A

SEROLOGY

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2
Q

The Antigen & Antibody bind specifically with each
other.

A

Antigen – Antibody Reaction

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3
Q

3 Stages of Ag-Ab Reactions

A

Formation of Ag-Ab complex
Formation of visible events
Destruction of Antigen

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4
Q

Formation of Ag-Ab complex

A

Binding/Recognition

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5
Q

Destruction of Antigen

A

Immune Response Activation and Neutralization

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5
Q

Formation of visible events

A

Agglutination and Precipitation

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6
Q

The combining site of an antibody is located in the Fab portion of the molecule and antigen nestles in a cleft.

A

Lock and Key Concept

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7
Q

Bonds that hold the antigen to the antibody

A

Non-covalent Bonds

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8
Q

Since Ag-Ab reactions occur via non-covalent
bonds, they are by their nature reversible.

A

Reversibility

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9
Q

formed between hydrogen of one molecule to usually, a nitrogen or oxygen in another molecule

A

Hydrogen bonds

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10
Q

attraction between oppositely charged ions (positive and negative charges)

A

Electrostatic bonds

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11
Q

Non-polar regions of the antigen and antibody tend to cluster together to avoid water, resulting in a stabilizing interaction.

A

Hydrophobic bonds

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12
Q

nonspecific attractive forces generated by the interaction between electron clouds and hydrophobic bonds

A

Van der Waals

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13
Q

refers to the strength of a single antibody-antigen
interaction. Each IgG antigen binding site has high
affinity for its target.

A

Affinity

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14
Q

refers to the strength of all interactions combined. IgM typically has low affinity antigen binding sites, but there are ten of them, so avidity is high.

A

Avidity

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15
Q

measures the acidity or alkalinity of a
solution

A

pH

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16
Q

neutral pH between

A

6.8-7.0

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17
Q

incubation period allows Ag-Ab to
optimally bind to each other

A

Time

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18
Q

shortens distance between Ag and Ab, allowing interaction to occur

A

Centrifugation

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19
Q

influences antibody action

A

Temperature

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20
Q
  • Best at 37oC
  • Can cross the placenta
A

Warm-reacting Ab

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21
Q

Physical Form of the Antigen that is more visible reactions

A

Cellular antigens

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21
Q
  • Best at 4-22oC
  • Can activate complement
A

Cold-reacting Ab

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22
Q

Physical Form of the Antigen that is less
visible reactions

A

Soluble antigens

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23
detects presence or absence of Ab/Ag
Qualitative test
24
determine concentration of Ab/Ag
Quantitative test
25
– concentration of an antibody expressed as the highest dilution of a serum that produces a positive result.
Titer
26
time where antibodies start to appear the development of detectable specific antibodies in serum
Seroconversion
27
time where antibodies start to disappear
Seroreversion
28
The ability of a population of Ab molecules to react with more than one antigen.
Cross reactivity
29
ability of a test to detect a very small amounts of a substance
analytical sensitivity
30
ability of a test to give positive result if px has the disease
clinical sensitivity
31
represent cases in which individuals with the particular disease test negative by a certain test
False-negatives
32
ability of test to detect substance without interference from cross-reacting substances
analytical specificity
32
ability of test to give negative result if patient does not have disease
clinical specificity
32
with visible effects
SECONDARY
32
represent cases in which individuals without the particular disease test positive by certain tests
False-positives
32
– rapid initial reaction without visible effects
PRIMARY
33
– In vivo testing
TERTIARY
34
* Detects initial interaction between antigen and antibody * Not visible to the naked eye
Primary / Initial Reactions
35
any substance that will complex to another substance
Ligand/Analyte
36
pros of Primary / Initial Reactions
– Highly sensitive – Can detect picogram or nanogram amounts of Ag or Ab concentration
36
one reactant is labeled so that the amount of binding can be measured
Ligand assay
37
Cons of Primary / Initial Reactions
– Expensive – Hazardous to health – Requires special training
37
* Patient antigen in the serum competes with labelled antigen to limited binding sites in immobilized antibodies on the test medium * Detects antigens (+) * Inverse relationship
Competitive Reaction
38
* Patient antigen in the serum competes with labelled antigen to limited binding sites in immobilized antibodies on the test medium * Detects antibodies (+)
Indirect Noncompetitive
38
Immobilized antibodies specific for patient Ag Detects antigens (+)
Sandwich / Capture Noncompetitive
39
* Uses radioisotopes as labels (Carbon14, 135I, 131I, tritium) * Measured by scintillation counter or gamma/beta rays counter * More sensitive than ELISA
Radioimmunoassays
40
Detects total IgE (+)
Radioimmunosorbent test (RIST)
40
Detects allergen specific IgE (+)
Radioadsorbent test (RAST)
41
* Use enzyme as ligand + chromogenic substrate → colorimetric rxn * Measured by spectrophotometer * Less sensitive than RIA
Enzyme-Linked Immunosorbent Assay (ELISA)
42
* Detected by flow cytometer * Uses fluorescent dyes
Immunofluorescence assay (IFA)
43
color of Fluorescein isothiocyanate
green
44
color of Tetramethyl rhodamine
red
44
color of 4’,6-diamidino-2-phenylindole
blue
45
color of Alexa flour dyes
multiple colors
45
Detects consequence (outcome) of antigen-antibody binding * Pros: – Directly visible to the naked eye – No label needed * Cons: – Less sensitive
Secondary Reactions
46
* Involves the actions of antibody (agglutinin) and cellular/particulate antigen (agglutinogen)
Agglutination
46
Upfront reaction of antibodies to antigens which are part of the cell surface ; detects antibodies (+)
Direct Agglutination
46
* Antigen binds to soluble antibody coated on carrier particles resulting to agglutination * Detects antigens (+)
Reverse Passive Agglutination
47
An agglutination reaction that employs particles that are coated with antigen not normally found in the cell surface Detects antibodies (+)
Passive Agglutination
48
* Autoantibody binds to Fc portion of labprepared antibodies in which Fab sites have coated carrier particles causing agglutination * Detects antibodies (+)
Modified Reverse Passive Agglutination
49
* Using protein A of inert bacteria S. aureus, in which Fc portion of IgG binds to, leaving the Fab sites free to interact with antigen of patient sample * Detects antigens (+)
Coagglutination
50
* Makes use of some viruses that have receptors for red blood cell (RBC) antigens * Detects antigens (+)
Viral Hemagglutination
51
Also known as Coombs’ Test or Antiglobulin Test (AGT)
Coombs Test
51
the degree of negative charge on the surface of a red blood cell
Zeta potential
51
* Detects antibodies (+) ; positive result is absence of agglutination since RBCs not clumped
Agglutination Inhibition Reaction
52
Autoantibodies (IgG) + own red cells
Autoimmune Hemolytic Anemia
52
Recipient antibodies + donor red cells
Hemolytic Transfusion Reactions
52
Detect in vivo binding of IgG to RBCs
Direct Coombs’ Test
53
used to detect very low concentrations of antibodies present in a patient's plasma/serum prior to a blood transfusion
Indirect Coombs Test
53
Maternal antibodies + fetus red cells
Hemolytic Disease of the Newborn)
53
used to detect antibodies or complement proteins bounded to the surface of RBCs
direct Coombs test
53
* Detects in vitro binding of IgG to RBCs * Also known as indirect antiglobulin test (IAT)
Indirect Coombs’ Test
54
* Ability of specific antibodies to block the site(s) on bacteria or viruses that they use to enter cell * Positive result is no cell lysis
Neutralization
54
* Detects fixed amount of antibodies (+) * Positive result is no hemolysis
Complement Fixation Test
55
* Uses soluble antigen to detect IgG (+) * Positive result is a precipitate (+)
Precipitation
56
* In vivo serologic reactions * Determination of the protective value of antiserum in the test
Tertiary Reactions