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Molecular Immunology > Exam 1 (Lectures 3/4) > Flashcards

Exam 1 (Lectures 3/4) Flashcards

1
Q

True or False: Antibodies are glycosamines

A

False - glycoproteins

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2
Q

True or False: All the below mentioned are POSITIVE outcomes of antibody production

-Neutralize viruses and toxins
-Accelerate clearance of bacteria
-Use for clinical assays
-Use as therapies to kill tumor cells

A

True

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3
Q

True or False: Allergies, Immune Complex Disease, and Autoimmunity are NEGATIVE outcomes of antibody production

A

True

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4
Q

What’s the major difference between immunoglobulins and antibodies?

A
  • Immunoglobulin (Ig): General term for all antibody molecules
  • Antibodies: Immunoglobulins made by TERMINALLY DIFFERENTIATED B LYMPHOCYTES in response to foreign antigen
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5
Q

True or False: The constant region defines the isotype of the heavy chain

A

False - the conserved region defines isotype of heavy chain

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6
Q

True or False: In an antibody, both light chains and heavy chains are identical

A

True

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7
Q

What determines the heavy chain type?

A

The amino acid

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8
Q
A
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9
Q

Which part of the antibody binds to the antigen?
A. Fab Region
B. Constant Region
C. Fc Region
D. Fragment of Antigen Binding

A

A.) Fab Region and
D.) Fragment of Antigen Binding

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10
Q

Which part of the antibody forms idiotype? the isotype?

A

-Idiotype = The Fab Region
-Isotype = Fc Region

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11
Q

Fab binds to ___ antigen while F(ab)2 binds ___ antigens

A

1, 2

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12
Q

Where is the Constant Region located: the Fab Region or the Fc Region?

A

Fc Region

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13
Q

Which region of the antibody contains biological activity: the Fab region or crystallized fragment region?

A

Crystallized fragment region (Fc)

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14
Q

True or False: Opsonization and helping to lyse microorganisms are examples of biological activity carried out by the Fc Region

A

True

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15
Q

What region of the antibody is found on BOTH the heavy and light chains, is encoded in the genome, and is same between antibody molecules

A

The Constant Region

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16
Q

Which Ig is the major Ig isotype in serum and crosses the placenta?

A

IgG

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17
Q

Where is the Variable Region located?

A

Portion of heavy and light chain that binds epitope

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18
Q

IgM is secreted by plasma cells as ____ and is joined by ____ chains

A

pentamer; J chains

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19
Q

True or False: IgM binds 10 antigens at a time

A

False - Despite 10 F(ab) it only binds 5 antigens at a time

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20
Q

What is the first Ig synthesized in response to an antigen?

A

IgM

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21
Q

Which Ig is a dimer in mucus secretions and is linked by J chains?

A

IgA

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22
Q

What is the major Ig found in external secretions (saliva, sweat, tears)?

A

IgA

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23
Q

True or False: IgE has lowest serum concentration

A

True

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24
Q

True or False: IgE is an agglutinating antibody and a complement-activating Ab

A

False - it is NEITHER

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25
Q

Which Ig protects host from parasitic infections by interaction with eosinophils?

A

IgE

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26
Q

Which Ig mediates Type 1 Hypersensitivity Responses (allergies)?

A

IgE

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27
Q

Which Ig is the only to be susceptible to proteolytic degradation?

A

IgD

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28
Q

Which Ig is a marker of B Cell differentiation?

A

IgD

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29
Q

Two fates of Ig molecules?

A

1) Secreted (terminally differentiated B cells) 2) Anchored in the B cell membrane + acts as antigen receptor for cell

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30
Q

___: The inverse of the highest dilution of a substance that reacts with a fixed amount of target material

A

Titer

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31
Q

Three clinical uses of serology?

A

1) Obtain specific diagnosis using antibody response - 4x increase in titer
2) Screen population
3) Monitor treatment efficacy

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32
Q

____: Measure of the ability of a test to exclude non-diseased cases

_____: Measure of the ability of a test to identify diseased cases

A

Specificity: Measure of the ability of a test to exclude non-diseased cases

Sensitivity: Measure of the ability of a test to identify diseased cases

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33
Q

When are SPECIFIC tests most helpful?
When tests are….
positive or negative?
to rule in or rule out?

A

SPECIFIC TESTS are most helpful when test is (+) to rule in

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34
Q

Which tests is likely to identify those who do NOT have disease: Specific Tests or Sensitive Tests?

A

Specific Tests

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35
Q

True or False: PCR (RNA Amplification) is an example of sensitive tests while an at-home pregnancy tests, EIA and antigen testing are specific

A

PCR = specific test
Pregnancy tests, EIA, antigen = sensitive test

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36
Q

What test is most helpful when it’s negative (to rule out) and is likely to identify everyone with the disease?

A

Sensitive Tests

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37
Q

Screening tests should have high ____ while confirmatory tests should have high _____

A

sensitivity; specificity

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38
Q

If antibodies are so specific, why do get false positives?

A

Similar antigens/epitopes may cross-react

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39
Q

Are ELISA’s and Enzyme Immunoassay (EIA) qualitative or quanitative?

A

Enzyme-Linked ImmunoSorbent Assay (ELISA): Quanitative

EIA: Qualitative

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40
Q

True or False: ELISA are used to find antigen or antibody in patient’s serum/secretions

A

False - Enzyme Immunoassay (EIA) are used to find antigen or antibody in patient’s serum/secretions

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41
Q

True or False: Immunofluorescence Assay is good for localizing antigen using fluorescently labeled antigens

A

True

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42
Q

Direct IFA detect antigen located in the ___ while IFA detects antigen located in ____

A

tissue; serum

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43
Q

What type of Immunofluorescence Assay would you use for biopsy/peripheral blood/rabies?

A

Direct IFA

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44
Q

What type of IFA is associated with:
- Nuclear antigens (autoimmunity)
-Infectious agents
-Lupus

A

Indirect IFA

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45
Q

What are the clinical uses of Flow Cytometry?

A

1) CD4:CD8 ratios in HIV
2) Analyze tumor cells for markers
3) Analyze peripheral blood for % of cell types

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46
Q

True or False: Fluorescence Activated Cell Sorting (FAC) is used to isolate and purify specific cell populations AND sort cells for use in transplant/lab

A

True

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47
Q

True or False: Both Flow Cytometry and Fluorescence Activated Cell Sorting use fluoresceinated antibodies to measure:
1) Cell size and number
2) Density of cell surface molecules
3) Number of cells with a certain cell-surface molecule

A

True

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48
Q

What does precipitation in a secondary binding test tell you about the antigen?

What does agglutination in a secondary binding test tell you about the antigen?

A

Precipitation means that antigen is SOLUBLE
Agglutination means that the antigen is INSOLUBLE

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49
Q

____ Antibody: reacts with soluble antigen resulting in formation of insoluble precipitate

A

Precipitin Antibody (Ab)

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50
Q

What type of antibody reacts with an insoluble antigen, results in clumping

A

Agglutinin

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51
Q

What are the two types of precipitation reactions?

A

1) Immunodiffusion Tests (Ouchterlony Test)
2) Radial Immunodiffusion Tests

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52
Q

What do Ouchterlony and Radial Immunodiffusion Tests have in common? (hint: antigen)

A

Both use SOLUBLE antigens

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53
Q

True or False: Immunodiffusion Tests (Ouchterlony Test) are qualitative and used to test/ID parasitic infections

A

False -
While immunodiffusion tests are qualitative, they are used clinically to test/ID fungal diseases

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54
Q

Are Radial Immunodiffusion Tests qualitative or quantitative? Clinical uses?

A

Radial Immunodiffusion Tests, a type of precipitation reaction, is quantitative and used to determine [IgG isotypes] in serum

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55
Q

Clinical uses of Direct Agglutination?

What type of antigens are used in Direct Agglutination?

A

Blood Typing

Direct Agglutination reactions use insoluble antigens (e.g RBC)

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56
Q

True or False: In Indirect/Passive agglutination reactions, a INSOLUBLE antigen of interest is attached to a SOLUBLE antigen

A

False

In an indirect/passive agglutination reactions, a SOLUBLE antigen of interest is attached to a INSOLUBLE antigen

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57
Q

Many proteins factors in the complement system are found in the ___ as inactive (zymogens)

A

serum

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58
Q

What molecules/structures are responsible for making the zymogens for the complement system?

A

Liver, monocytes, macrophages

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59
Q

What are the major functions of the complement system?

A

1) Opsonization “prepare food”
2) Recruit and activate phagocytic and inflammatory cells to site of complementation activation
(anaphylatoxins)
3) Margination
4) Regulate vascular tone

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60
Q

_____: small MW substance that induces degranulation of mast cells and release of histamine/other vasoactive substances

A

Anaphylatoxins

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61
Q

C3a, C4a and C5a components are referred to as ____

A

Anaphylatoxins
C5a (strongest), C3a, C4a (weakest)

62
Q

C3b and C4b act as ____, thereby tagging microorganisms, dead cells, antigens, etc. for phagocytosis by macrophages and neutrophils — which possess complement receptors (!)

A

opsins

63
Q

What two molecules regulate vascular tone?

A

C2 and C2 kinin

64
Q

_____: A process in inflammation that allows leukocytes to adhere to endothelium of vessel walls in preparation for movement from vasculature to site of inflammation

A

Margination

65
Q

True or False: Margination is associated with C5a

A

True

66
Q

____: Movement of leukocytes through a gradient toward increasing concentrations of a substance

A

Chemotaxis

67
Q

What are two chemoattractants for WBC’s?

A

C5a and C3a

68
Q

What is the ultimate goal of the Complement System?

A

Form the membrane attack
complex (MAC) which results in cell lysis.

69
Q

What molecule removes Immune Complexes?

A

RBC’s (via CR1) - they move to the RE system (liver and spleen) and undergo phagocytosis

70
Q

Opsonization describes the _____and is
mediated by complement protein______.

A. Tagging of microorganisms - C3b
B. Tagging of microorganisms – C5a
C. Directional migration of leukocytes – C3b
D. Directional migration of leukocytes – C5a
E. Regulation of vascular tone – C3b
F. Regulation of vascular tone – C5a

A

A. Tagging of microorganisms - C3b

71
Q

What are the three activation pathways?

A

1) Classical
2) Alternate
3) Lectin

72
Q

All three activation pathways result in the formation of _____

A

C3 Convertase

73
Q

True or False: The complementation pathways converge at a single terminal pathway

A

True

74
Q

If not removed, IC’s (immune complexes) tend to aggregate, enlarge, and precipitate in basement membrane of small blood vessels in the kidney glomeruli, synovium, and skin

A

True

75
Q

C3 convertase is an important amplification step in both the
___and ___complement pathways.

A

alternative ; classical

76
Q

True or False: A single C3 convertase can activate hundreds
of C3 molecules

A

True

77
Q

What is the order in which the C molecules (4) are activated in the Classical Activation Pathway?

A

C1, C4, C2, C3

78
Q

How is the classical pathway activated?

A

1) Antigen-antibody complexes containing IgM or IgG

79
Q

C1 binds to ___ portion of the antibody, leading to its activation

A

Fc

80
Q

What is required for C1 activation?

A

Simultaneous binding to TWO molecules of Fc in close proximity (either 2 molecules of IgG in close proximity to one another or 1 molecule of IgM)

81
Q

Once C4b accepts C2, what does activate C1 (C1’) do?

A

C1’ cleaves C2 → C2a + C2b, → C4b2b Complex

82
Q

In the classical activation pathway, what complex cleaves C3 into C3a and C3b?

A

C4b2b Complex

83
Q

Once C4b2b Complex cleaves C3 into C3b and C3a, ___ binds to the membrane and ____ is formed

A

C3b ; C4b2b3b

84
Q

What gives the classical activation pathway more control and allows for
regulation PRIOR to amplification of the pathway, to the point in which potent
inflammatory mediators are produced in abundance?

A

Weaker anaphylatoxins are generated first (C4a then C3a) and the more
potent one is generated last (C5a)

85
Q

True or False: The Alternative Pathway functions in the presence of antibodies

A

False - the Alternative Pathway functions in the ABSENCE of antibodies

86
Q

What activates the Alternative Pathway?

A

Anything that hydrolyses C3
* leukocyte proteases
* plasmin
* bacteria or bacterial products (LPS, bacterial cell wall components)
* aggregated IgA
* cobra venom factor
* Cellophane
* Water “Ticking over”

87
Q

Activation of Alternative Pathway occurs via hydrolysis of ___

A

C3

88
Q

What factor binds to C3b in the alternative pathway?

A

Factor B

89
Q

Factor B is a substrate for Factor ___

A

D

90
Q

What is the role of Factor D in the Alternative Activation Pathway?

A

Factor D cleaves B to form C3bBb (the alternative pathway C3 convertase)

91
Q

The Alternative Pathway is also known as the _______

A

Properidin Pathway

92
Q

True or False: There is a amplification loop of C3 cleavage in the properidin pathway

A

True

93
Q

Which molecule of the alternative pathway is so unstable that it requires Factor P to stabilize it?

A

Properdin (Factor P) binds to C3bBb and stabilizes it

94
Q

Under what conditions is there an explosive amplification of C3 cleavage in the Properidin Pathway?

A

When C3bBb-Properdin Complex binds and cleaves increasing amounts of C3

95
Q

True or False: Binding and cleavage by C3bBb-Properdin Complex increases the amounts of bound C3b AND further stabilizes C3bnBb-Properdin?

A

True

96
Q

C3bnBb-Properdin is also know as ______ in the Alternative Pathway, which allows for activation of terminal pathway

A

C5 convertase

97
Q

What protein in the Mannose Binding Lectin pathway binds to TERMINAL mannose residues of proteins and polysaccharides that are only located on surface of bacteria?

A

Mannose Binding Lectin (MBL)

98
Q

In the Manose Binding Lectin pathway, ___ is structurally homologous to C1 of classical pathway

A

Mannose Binding Lectin (MBL)

99
Q

What is the effect of Mannose Binding Lectin binding to mannose residues on bacterial surface?

A

Enzymatically activates MBL for same substrate as C1’

100
Q

Which pathway is responsible for formation of the membrane attack complex (MAC)?

A

Terminal Pathway

101
Q

What does the membrane attack complex do?

A

Pokes holes into cell membranes
-Cell membrane damage
-Cell lysis

102
Q

True or False: Once a stable C5 Convertase is formed by either activation pathway, they converge into a single terminal pathway

A

True

103
Q

C4b2b3b (classical) or C3bnBb (alternate pathway) act to cleave what molecule?

A

C5

104
Q

Once C5b is formed, C6-8 bind sequentially. Then, ___polymerizes and inserts itself into the cell membranes, forming a channel that allows ____

A

C9 ; osmotic lysis

105
Q

C_-_ are terminal complement components and form the membrane attack complex (MAC)

A

5-9

106
Q

What pathway does C1 Inhibitor (C1INH) inhibit?

A

Classical and Lectin

107
Q

How does C1INH inhibit Classical Pathway?

A

Dissociation of C1r and C1s from C1q

108
Q

True or False: C1INH limits the amount of time that C1’ is active in the alternative pathway

A

False -
C1INH limits the amount of time that C1’ is active in the classical pathway

109
Q

Where are DAF or CD55 located?

A

Decay Accelerating Factor
- cell surface

110
Q

What is the function of DAF or CD55?

A

Dissociates C4b2b
(classical C3 convertase)

and C3bBb
(alternative C3 convertase)

111
Q

True or False: Activation of CD55 can results in loss of enzymatic pathway and inhibition of either that alternative or classical pathway

A

True

112
Q

What pathway does Factor H inhibit?

A

Alternative pathway

113
Q

Factor H can disassociate ____ complexes

A

C3bBb

114
Q

Factor H competes with Factor __ for binding to C3b (surface bound)

A

Factor B

115
Q

Following dissociation of C4b2b or C3bBb by DAF, ____ cleaves the structures, preventing them from functioning

A

Factor I

116
Q

Serum Carboxypeptidase B is a _____ Inactivator

A

Anaphylatoxin

117
Q

True or False: The only real difference between the Lectin pathway and the classical pathway is that
MBL is substituted for C1 complex during initiation

A

True

118
Q

Which complement activation pathway(s) can
be activated by a bacterial infection?

A. Classical pathway
B. Lectin pathway
C. Alternative pathway
D. Classical and Lectin only
E. All three

A

E.

119
Q

Serum Carboxypeptidase B causes proteolytic removal of terminal ___ residues and inactivates anaphylatoxins

A

arginine

120
Q

Which molecule prevents insertion of MAC and cytolysis? How?

A

Vitronectin (S protein)

Binds to C5b67 complex

121
Q

What molecule PREVENTS C9 polymerization? How?

A

CD59 - binds to C5b-8

122
Q

Deficiency of C1, C4, C2, C3 or Factor I are associated with what conditions?

A

1) Deficiency in opsionization
2) Difficulty clearing IC’s
3) Susceptible to infx by encapsulated bactera

123
Q

Difficulty handling blood borne infections with Neisseria meningitidis (gram negative) is associated with what type deficiencies?

A. C1, C2, C3, C5 deficiency
B. C6, C6, C7, C8 deficiency
C. Factor H deficiency
D. Factor I deficiency

A

B. Deficiency of C5, C6, C7, or C8

124
Q

______ is associated with stress/trauma provoked vasodilatation and edema
usually of the skin, extremities, or GI mucosa

A

Type I Hereditary Angioedema

125
Q

What are individuals with Type I Hereditary Angioedema deficient in ?

A

C1 Esterase Inhibitor (C1INH)

126
Q

Which of the answers below is Factor H deficiency associated with?

A. Increased susceptibility to many bacteria
B. Increased infection by encapsulated bacteria and N. meningitis
C. Lysis of RBC/endothelial cells and hemolytic-ureimc syndrome

A

C. Lysis of RBC/endothelial cells and hemolytic-ureimc syndrome

127
Q

Properdin deficiency is associated with: _____

A. Increased infections by encapsulated bacteria and N. meningitis
B. Increased susceptibility to many bacteria
C. Lysis of RBC/endothelial cells and hemolytic-ureimc syndrome

A

A. Increased infections by encapsulated bacteria and N. meningitis

128
Q

MBL deficiency increases the susceptibility to MANY common bacterial infections including
1) _____
2) ____
3) ____

A

1) Neisseria meningitides
2) Streptococcus pneumoniae
3) Staphylococcus
aureus

129
Q

Which antibody is normally found on the surface of B cells, in association with IgM, where it acts as a receptor

A

True

130
Q

Serum half life of IgG, IgA, IgM, IgD, and IgE?

A

IgG = 23 days
IgA = 5.5 days
IgM = 5 days
IgD = 2.8 days
IgE = 2.0 days

131
Q

Which IgG largely activates complement and have high agglutination capacity?

A

IgM

132
Q

What two Ig’s have high neutralizing activity?

A

IgG and IgM

133
Q

_____: The multi-molecular complex formed upon binding of antigen with its antibody

A

Immune complex

134
Q

A serum sample is diluted 1:16 and still yields a positive response, but the next dilution higher yields a negative response. What is the titer?

A

16

135
Q

In clinical serology tests tests, either the ___ or ___ must be known

A

antibody; antigen

136
Q

_____: when different antigens/epitopes that are similar enough in structure, shape, charge can be bound by the same antibody

A

Cross Reactivity

137
Q

What type of binding tests are: direct and indirect Immunofluorescence, flow cytometry, and ELISA/EIA?

A

Primary Binding Tests

138
Q

Which test is best for determining titers?
A. ELISA
B. EIA
C. DFA
D. IFA

A

A. ELISA

139
Q

_____: tests that allow Ag and Ab to combine and then measure amount of immune complex formed

A

Primary Binding Tests

140
Q

Two examples of immunoassays?

A

1) Home pregnancy test
2) Rapid strep/rapid COVID

141
Q

What molecule is a highly potent chemotactic factor for neutrophils?

A

C5a

142
Q

What molecule is a highly potent chemotactic factor for neutrophils?

A

C5a

143
Q

What molecule triggers formation of MAC?
A. C5b
B. C6a
C. C5a

A

A. C5b

144
Q

True or False: Type I Hereditary Angioedema is associated with generation of bradykinin

A

True

145
Q

What may cause the spontaneous attacks seen in Type I Hereditary Angioedema?

A

1) Activation of bradykinin
2) Activation of C1 by plasmin
3) Generation of C4a

146
Q

What Factor competes with Factor B for binding to C3b and can dissociate C3bBb complex?

A

Factor H

147
Q

Following dissociation of C4b2b or C3bBb by DAF, Factor ____ cleaves the structures, preventing function

A

Factor I

148
Q
A
149
Q
A
150
Q
A
151
Q
A

Molecular Immunology (27 decks)

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