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IMMUNE1 LEC MIDTERM TRANSES > CHAPTER 6: PRECIPITATION AND AGGLUTINATION REACTIONS > Flashcards

CHAPTER 6: PRECIPITATION AND AGGLUTINATION REACTIONS Flashcards

1
Q

Combination of (?) plays an important role in the laboratory in diagnosing many different diseases.

A

antigen with specific antibody

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2
Q

have been developed to detect either antigen or antibody, and they vary from easily

A

Immunoassays

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3
Q

Immunoassays are based on the principles of

A

precipitation or agglutination

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4
Q

Initial force of attraction that exist between singe Fab site (paratope) and a single epitope on the corresponding antigen

A

Affinity

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5
Q

The strength of attraction depends on the specificity of antibody for a particular antigen

A

Affinity

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6
Q

Antibodies are capable of reacting with antigens that are structurally similar to the original antigen that induced antibody production. This is known as

A

crossreactivity

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7
Q

Sum of all attractive forces between an Ag and Ab

A

Avidity

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8
Q

Dictates the overall stability of the Ag-Ab complex

A

Avidity

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9
Q

= decreased tendency of the complex to dissociate.

A

High Avidity

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10
Q

occur between oppositely charged particles

A

Ionic bonds

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11
Q

involve an attraction between polar molecules that have a slight charge separation and in which the positive charge resides on a hydrogen atom

A

Hydrogen bonds

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12
Q

occur between nonpolar molecules that associate with one another and exclude molecules of water as they do so

A

Hydrophobic bonds

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13
Q

occur because of the interaction between the electron clouds of oscillating dipoles

A

Van der Waals forces

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14
Q

Types of Affinity

A
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15
Q

Antibody

A

Precipitin

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16
Q

Soluble antigens

A

Precipitinogen

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17
Q

Insoluble complexes formed by the union of the two aforementioned

A

Precipitate

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18
Q

Natural clumping. Fleecy, white/ coudy

A

Flocculation

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19
Q

Much better precipitating Ab than IgM

A

IgG

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20
Q

Much better agglutinating Ab than IgG

A

IgM

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21
Q

Precipitation:

A

IgG>IgM>IgA

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22
Q

Nonprecipitating

A

IgE

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23
Q

Involves combining soluble antigen with soluble antibody to produce insoluble complexes that are visible

A

PRECIPITATION

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24
Q

First noted in 1897 by Kraus

A

PRECIPITATION

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25
Q

: All antigen-antibody binding is reversible and free reactants are in equilibrium with bound reactants.

A

Law of Mass Action

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26
Q

Excess antibody is called the

A

prozone

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27
Q

excess antigen concentration is called the

A

postzone

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28
Q

Mnemonic:

A

ProAbPostAg

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29
Q

Zone of equivalence: Area wherein maximum precipitation will occur because Ag and Ab concentration must have an

A

optimum ratio or Ag and Ab are equal

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30
Q

In the case of antibody excess, the (?) occurs

A

prozone phenomenon

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31
Q

antigen combines with only one or two antibody molecules, and no cross-linkages are formed

A

prozone phenomenon

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32
Q

This is because usually only one site on an antibody molecule is used, and many free antibody molecules remain in solution.

A

prozone phenomenon

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33
Q

At the other side of the zone, where there is antigen excess, the (?) occurs

A

postzone phenomenon

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34
Q

small aggregates are surrounded by excess antigen, and again no lattice network is formed

A

postzone phenomenon

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35
Q

may lead to false negative

A

Prozone and postzone

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36
Q

Prozone phenomenon→

A

Serum dilution

37
Q

Postzone phenomenon→

A

Repeat the test after a week to give time for antibody production.

38
Q

FACTORS AFFECTING PRECIPITATION

A
39
Q

The pH of the medium used for testing should be near physiologic conditions, or an optimum pH of 6.5 to 7.5

A

pH

40
Q

Ideal: Body temperature (37C/98.6F)

A

Temperature and Length of Incubation

41
Q

40-45C

A

Temperature and Length of Incubation

42
Q

Incubation time range from 15-60 minutes

A

Temperature and Length of Incubation

43
Q

FACTORS AFFECTING PRECIPITATION

A

Precipitation in a fluid medium
Precipitation by a passive immunodiffusion
Precipitation by electrophoretic techniques.

44
Q

Precipitation in a
Precipitation by a
Precipitation by

A

Precipitation in a fluid medium
Precipitation by a passive immunodiffusion
Precipitation by electrophoretic techniques.

45
Q

Precipitation in a Fluid Medium

A
46
Q

is a measure of the turbidity or cloudiness of a solution

A

Turbidimetry

47
Q

A detection device is placed in direct line with the incident light, collecting light after it has passed through the solution.

A

Turbidimetry

48
Q

It thus measures the reduction in light intensity due to reflection, absorption, or scatter.

A
49
Q

Scattering of light occurs in proportion to the size, shape, and concentration of molecules present in solution.

A

Turbidimetry

50
Q

It is recorded in absorbance units, a measure of the ratio of incident light to that of transmitted light.

A

Turbidimetry

51
Q

Measurements are made using a spectrophotometer or an automated clinical chemistry analyzer.

A

Turbidimetry

52
Q

measures the light that is scattered at a particular angle from the incident beam as it passes through a suspension.

A

Nephelometry

53
Q

The amount of light scattered is an index of the solution’s concentration.

A

Nephelometry

54
Q

The precipitation of antigen–antibody complexes can also be determined in a support medium such as a gel.

A

Precipitation by a Passive Immunodiffusion

55
Q

: No electric current is used to speed up reaction of the Ag and Ab combination, but through DIFFUSION

A

Passive

56
Q

Factors affecting rate of diffusion

A

Size of the particles
Temperature
Gel viscosity
Amount of Hydration

57
Q

Precipitation in Gel Medium

A
58
Q

• Only one reactant is moving

A

Single Diffusion

59
Q

• Either Ag or Ab is moving

A

Single Diffusion

60
Q

• Both Ag and Ab are moving through the medium

A

Double Diffusion

61
Q

• Reaction in tubes- Ag or Ab migrate up and down

A

Single Dimension

62
Q

• Petri dish – Ag or Ab diffuse radially

A

Double Dimension

63
Q

• Ab is uniformly distribute in a support gel and Ag is applied to a well cut into gel.

A

Radial Immunodiffusions

64
Q

Procedure:
1. Ab mixed in agarose
2. Antigen dilution is overlaid (Ag must always be greater to achieve zone of equivalence)
3. Mobile Ag diffuses through the gel, containing immobilized Ab forming insoluble Ag-Ab Complexes.
4. At equivalence concentration, the Ag stops moving and a satbilized band is formed.

A

Single DiffusionSingle Dimension (Oudin)

65
Q

Procedure:
1. Ab is mixed with liquid agar and poured into the petri dish
2. Circular wells cut in gel
3. Ag is loaded into the wells
4. Ring precipitate expands from the well as Ag diffuses toward its equilibrium concentration
5. Diameter of the disc is measured.

A

Single DiffusionDouble Dimension (Macini, Fahey, and MacKelvey)

66
Q

Single DiffusionDouble Dimension (Macini, Fahey, and MacKelvey) Types:

A

A. Mancini/Endpoint Method

B. Fahey and McKelvey/Kinetic method

67
Q

Diameter= Ag Concentration

A

Mancini/Endpoint Method

68
Q

In this technique, antigen is allowed to diffuse to completion, and when equivalence is reached, there is no further change in the ring diameter.

A

Mancini/Endpoint Method

69
Q

This occurs between 24 and 72 hours.

A

Mancini/Endpoint Method

70
Q

The square of the diameter is then directly proportional to the concentration of the antigen.

A

Mancini/Endpoint Method

71
Q

Diameter= Logarithm Ag Concentration

A

Fahey and McKelvey/Kinetic method

72
Q

Uses measurements taken before the point of equivalence is reached.

A

Fahey and McKelvey/Kinetic method

73
Q

Antigen is not allowed to diffuse completely.

A

Fahey and McKelvey/Kinetic method

74
Q

In this case, the diameter is proportional to the log of the concentration.

A

Fahey and McKelvey/Kinetic method

75
Q

Readings are taken at about 18 hours.

A

Fahey and McKelvey/Kinetic method

76
Q

Mnemonic: “FAK ME”

A

FA→Kinetic
Mancini→Endpoint

77
Q

Both Ag and Ab diffuse independently through a semisolid medium in 2 dimension

A

Ouchterlony Double Diffusion

78
Q

Procedure
1. Pattern of well in cute in an agarose gel in petri dish
2. Reactants are loaded
3. Incubated until lines are precipitated

A

Ouchterlony Double Diffusion

79
Q

Possible Patterns in Ouchterlony Double Diffusion:

A
80
Q

Fusion of the lines at their junction to form an arc represents serological identity or the presence of a common epitope

A

A. Serological Identity: Identical Ag

81
Q

The arc indicates that the two antigens are identical.

A

A. Serological Identity: Identical Ag

82
Q

• Pattern of crossed lines demonstrates two separate reactions and indicates that the compared antigens share no common epitopes

A

B. Non-Indentity: Ag are serologically distinct

83
Q

• Two crossed lines represent two different precipitation reactions. The antigens share no identical determinants.

A

B. Non-Indentity: Ag are serologically distinct

84
Q

. • “Spur formation”

A

C. Partial Identity: Ag are not identical but do possess common determinants

85
Q

• Fusion of two lines with a spur indicates partial identity.

A

C. Partial Identity: Ag are not identical but do possess common determinants

86
Q

• The two antigens share a common epitope, but some antibody molecules are not captured by antigen and travel through the initial precipitin line to combine with additional epitopes found in the more complex antigen

A

C. Partial Identity: Ag are not identical but do possess common determinants

87
Q

: technique in which molecules with a net charge are separated when an electric field applied

A

Electrophoresis

88
Q

• Negative charged particles migrate to the

A

ANODE (Postive (+) Pole)

89
Q

• Positive charged particles migrate to the

A

CATHODE (Negative (-) pole)

IMMUNE1 LEC MIDTERM TRANSES (4 decks)

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