ANTIBODIES Flashcards
memorization
1
Q
Specific glycoproteins referred to as immunoglobulins; produced in response to antigenic stimulation
A
Antibodies
2
Q
Enumerate functions of immunoglobulins:
A
- Neutralize toxic substances
- Facilitate phagocytosis through opsonization
- Kill microbes
- Combine with Ag on cell surfaces and thereby cause destruction of cells
3
Q
This type of bond connects a heavy chain to heavy chain and heavy chain to light chain.
A
Disulfide bonds
4
Q
A light chain-to-light chain connection is seen in:
A
Bence Jones Protein
5
Q
The hinge region is located between ______ and _________.
A
Constant Heavy chain 1 (CH1) and Constant Heavy chain 2 (CH2)
6
Q
This immunoglobulin region allows the Ig to take on different shapes:
A
Hinge region
7
Q
High _______ content gives the Immunoglobulin flexibility
A
Proline
8
Q
How many domains do IgM and IgE have?
A
5 domains
9
Q
How many domains do IgG, IgA, and IgD have?
A
4 domains
10
Q
Light chain antiboy molecules:
A
Kappa
Lambda
11
Q
Heavy chain antibody isotypes:
A
Mu (IgM)
Gamma (IgG)
Alpha (IgA)
Delta (IgD)
Epsilon (IgE)
12
Q
The first approximately 110 amino acids at the amino-terminal end constitute the _______ domain:
A
Variable domain
13
Q
Valence in immunoglobulins refers to:
A
number of binding sites
14
Q
Monomer immunoglobulin has ____ binding sites:
A
2 binding sites
15
Q
Dimer immunoglobulins has ____ binding sites:
A
4 binding sites
16
Q
Pentameric IgM has ____ binding sites:
A
10 binding sites
17
Q
Which of the following is a characteristic of variable domains of immunoglobulins?
a. They occur on both the H and L chains.
b. They represent the complement-binding site.
c. They are at the carbox-terminal ends of the molecules
d. They are found only on H chains
A
a. They occur on both the H and L chains
18
Q
All of the following are true of IgM except that it
a. can cross the placenta
b. fixes complement
c. has a J chain
d. is a primary response antibody.
A
a. can cross the placeta
19
Q
How does the structure of IgE differ from that of IgG?
a. IgG has a secretory component and IgE does not.
b. IgE has one more constant region than IgG
c. IgG has more antigen-binding sites than IgE
d. igG has more light chains than IgE
A
b. IgE has one or more constant region than IgG
20
Q
How many antigen-binding sites does a typical IgM molecule have?
a. 2
b. 4
c. 6
d. 10
A
d. 10
21
Q
Bence Jones Proteins are identical to which of the following?
a. H chains
b. L chains
c. IgM molecules
d. IgG molecules
A
b. L chains
22
Q
A Fab fragment consists of
a. two H chains
b. two L chains
c. one L chain and one-half of an H chain
d. one L chain and an entire H chain
A
c. one L chain and one-half of an H chain
23
Q
Which antibody best protects mucosal surfaces?
a. IgA
b. IgG
c. IgD
d. IgM
A
a. IgA
24
Q
Which of the following pairs represents two different immunoglobulin allotypes?
a. IgM and IgG
b. IgM1 and IgM2
c. Anti-human IgM and anti-human IgG
d. IgG1m3 and IgG1m17
A
d. IgG1m3 and IgG1m17
- IgM and IgG (option a) are different classes of immunoglobulins, not allotypes.
- IgM1 and IgM2 (option b) are subclasses, not allotypes.
- Anti-human IgM and anti-human IgG (option c) are antibodies against different immunoglobulins, not allotypes.
- IgG1m3 and IgG1m17 (option d) represent different allotypes of the IgG1 subclass, varying in their genetic markers (m3 and m17).
25
The structure of a typical immunoglobulin consists of which of the following?
a. 2L and 2H chains
b. 4L and 2H chains
c. 4L and 4H chains
d. 2L and 4H chains
a. 2L and 2H chains
A typical immunoglobulin (antibody) has:
2 Heavy Chains (H)
2 Light Chains (L)
This structure is often represented as: H2L2
- Heavy chains (H): 2 identical chains, each consisting of:
- 1 variable region (VH)
- 3-4 constant regions (CH1, CH2, CH3)
- Light chains (L): 2 identical chains, each consisting of:
- 1 variable region (VL)
- 1 constant region (CL)
26
Which of the following are L chains of antibody molecules?
a. Kappa
b. Gamma
c. Mu
d. Alpha
a. Kappa
27
If the result of serum protein electrophoresis show a significant decrease in the gamma band, which of the following is a likely possibility?
a. Normal response to active infection
b. Multiple Myeloma
c. Immunodeficiency disorder
d. Monoclonal gammopathy
c. Immunodeficiency disorder
- Normal response to active infection (a): Typically, gamma globulins increase in response to infection.
- Multiple Myeloma (b): Characterized by an increase (M-protein spike) in the gamma band, not a decrease.
- Immunodeficiency disorder (c): Conditions like hypogammaglobulinemia, agammaglobulinemia, or combined immunodeficiency lead to decreased immunoglobulin production.
- Monoclonal gammopathy (d): Typically presents with an increase (M-protein spike) in the gamma band.
28
The subclasses of IgG differ mainly in
a. the type of L chain
b. the arrangement of disulfide bonds
c. the ability to act as opsonins
d. molecular weight
b. the arrangement of disulfide bonds
29
Which best describes the role of the secretory component for IgA?
a. A transport mechanism across endothelial cells
b. A means of joining two IgA monomers together
c. An aid to trapping antigens
d. Enhancement of complement fixation by the classical pathway
a. A transport mechanism across endothelial cells
The secretory component (SC) plays a crucial role in the transport of IgA antibodies across endothelial cells, facilitating their secretion into mucosal surfaces, such as:
1. Respiratory tract
2. Gastrointestinal tract
3. Genitourinary tract
The SC:
1. Binds to IgA molecules
2. Forms secretory IgA (sIgA)
3. Transports sIgA across endothelial cells via transcytosis
4. Protects IgA from proteolytic degradation
This ensures IgA antibodies reach mucosal surfaces, providing immune protection against pathogens.
b. J-chain, not SC, joins IgA monomers.
c. IgA's trapping antigens is a function of its antibody activity, not SC.
d. SC doesn't enhance complement fixation; IgA activates the alternative complement pathway.
Note: IgA's primary function is mucosal immunity, not complement activation.
30
Which represents the main function of IgD?
a. Protection of the mucous membranes
b. Removal of antigens by complement fixation
c. Enhancing proliferation of B cells
d. Destruction of parasitic worms
c. Enhancing proliferation of B cells
IgD's main function:
1. Expressed on mature B cells' surface
2. Acts as a receptor for antigen recognition
3. Activates B cells upon antigen binding
4. Enhances B cell proliferation and differentiation
IgD:
1. Plays a key role in the initiation of immune responses
2. Involved in antigen presentation and processing
3. Collaborates with IgM in early immune responses
The other options are incorrect:
a. IgA protects mucous membranes.
b. IgG and IgM are primarily involved in complement fixation.
d. IgE, not IgD, is associated with parasitic worm destruction.
Note: IgD's exact function is still debated, but its role in B cell activation and proliferation is well-established.
31
Which antibody is best at agglutination and complement fixation?
a. IgA
b. IgG
c. IgD
d. IgM
d. IgM
IgM:
1. Most effective at agglutination (clumping of particles/organisms)
2. Strongest activator of the classical complement pathway
3. Provides immediate protection against infections
Characteristics:
1. Large pentameric structure (5 Ig units)
2. High avidity (binding strength)
3. Efficient at neutralizing pathogens
32
Which of the following can be attributed to the clonal hypothesis of antibody formation?
a. Plasma cells make generalized antibody
b. B cells are preprogrammed for specific antibody synthesis
c. Proteins can alter their shape to conform to antigen
d. Cell receptors break off and become circulating antibody
b. B cells are preprogrammed for specific antibody synthesis
The Clonal Selection Hypothesis (1957) by Sir Frank Macfarlane Burnet states:
1. Each B cell is genetically pre-programmed to produce a unique antibody specificity.
2. Antigen binding selects and activates specific B cells.
3. Activated B cells proliferate and differentiate into plasma cells.
4. Plasma cells produce large amounts of their specific antibody.
Key points:
- B cells are pre-committed to produce specific antibodies.
- Antigen exposure selects and expands specific B cell clones.
- Clonal expansion ensures specific immune responses.
a. Plasma cells produce specific antibodies, not generalized.
c. Proteins can change shape, but this isn't directly related to clonal hypothesis.
d. Cell receptors don't break off to become circulating antibodies; B cells differentiate into plasma cells to produce antibodies.
This fundamental concept in immunology explains how our immune system generates specific responses to diverse antigens.
33
All of the following are true of IgE except that it
a. fails to fix complement
b. is heat stable
c. attaches to tissue mast cells
d. is found in the serum of allergic persons
b. is heat stable
IgE characteristics:
1. Fails to fix complement (correct)
2. Heat-labile (not stable), unlike other immunoglobulins
3. Attaches to tissue mast cells and basophils (correct)
4. Found in the serum of allergic persons (correct)
IgE's heat lability means it:
1. Denatures easily at high temperatures
2. Loses activity when exposed to heat
IgE's roles:
1. Mediates allergic reactions (Type I hypersensitivity)
2. Involved in parasitic infections and immune responses
Other immunoglobulins (IgG, IgM, IgA, IgD) are generally heat stable.
Note: IgE's heat lability is an important distinction as it affects laboratory handling and storage procedures.
34
Which best describes coding for immunoglobulin molecules?
a. All genes located on the same chromosome
b. L chain rearrangement occurs before H chain rearrangement
c. Four different regions are involved in coding of H chains
d. Lambda rearrangement occurs before kappa rearrangement
c. Four different regions are involved in coding of H chains
Immunoglobulin (Ig) molecule coding involves:
1. Variable (V) region: encodes antigen-binding site
2. Diversity (D) region: adds diversity to V region
3. Joining (J) region: joins V and D regions
4. Constant (C) region: determines Ig class (e.g., IgG, IgM)
These four regions encode the Heavy (H) chain. Light (L) chains have only V, J, and C regions.
Key points:
- H chain rearrangement occurs after L chain rearrangement (not option b)
- Ig genes are located on different chromosomes (not option a):
- Heavy chain genes: chromosome 14
- Kappa (κ) light chain genes: chromosome 2
- Lambda (λ) light chain genes: chromosome 22
- Kappa (κ) rearrangement usually occurs before lambda (λ) rearrangement (opposite of option d)
Immunoglobulin gene rearrangement and expression:
1. V(D)J recombination: generates unique antigen receptors
2. Somatic hypermutation: introduces mutations for affinity maturation
3. Class switch recombination: changes Ig class (e.g., IgM to IgG)
Understanding Ig molecule coding is crucial for appreciating immune diversity and function.
35
What is the purpose of HAT medium in the preparation of monoclonal antibody?
a. Fusion of the two cell types
b. Restricting the growth of myeloma cells
c. Restricting the growth of spleen cells
d. Restricting antibody production of the IgM class
b. Restricting the growth of myeloma cells
HAT (Hypoxanthine-Aminopterin-Thymidine) medium is used in monoclonal antibody production to:
1. Select for hybridoma cells (fusions of B cells and myeloma cells)
2. Inhibit the growth of unfused myeloma cells
HAT medium contains:
1. Aminopterin: blocks nucleotide synthesis
2. Hypoxanthine and thymidine: provide alternative pathways for nucleotide synthesis
Only hybridoma cells, having functional hypoxanthine-guanine phosphoribosyltransferase (HGPRT) enzyme from B cells, can survive in HAT medium.
HAT medium does not:
c. Restrict spleen cell growth (they die off naturally)
d. Restrict antibody production of the IgM class (HAT medium doesn't affect antibody class)
Monoclonal antibody production steps:
1. Immunization and spleen cell isolation
2. Cell fusion with myeloma cells
3. HAT medium selection
4. Hybridoma screening and cloning
5. Antibody production and purification
HAT medium is crucial for selecting and expanding specific hybridoma cells, producing desired monoclonal antibodies.
36
Papain digestion of an IgG molecule results in which of the following?
a. 2 Fab' and 1 Fc' fragment
b. F(ab')2 and 1 Fc' fragment
c. 2 Fab and 2 Fc fragments
d. 2 Fab and 1 Fc fragment
d. 2 Fab and 1 Fc fragment
Papain digestion of IgG:
1. Cleaves IgG at the hinge region
2. Produces:
- 2 Fab (Fragment Antigen-binding) fragments
- 1 Fc (Fragment crystallizable) fragment
Fab fragments:
- Retain antigen-binding activity
- Consist of VL, VH, CL, and CH1 domains
Fc fragment:
- Responsible for effector functions (e.g., complement activation)
- Consists of CH2 and CH3 domains
Papain digestion characteristics:
- Occurs at the hinge region's susceptible sites
- Yields monovalent Fab fragments (bind single antigen epitope)
Other proteases:
- Pepsin: produces F(ab')2 and pFc' fragments
- Trypsin: produces Fab' and Fc' fragments (similar to papain)
37
Which antibody provides protection to the growing fetus because it is able to cross the placenta?
a. IgG
b. IgA
c. IgM
d. IgD
a. IgG
38
Which best characterizes the secondary response?
a. Equal amounts of IgM and IgG are produced
b. There is an increase in IgM only
c. There is a large increase in IgG but not IgM
d. The lag phase is the same as in the primary response
c. There is a large increase in IgG but not IgM
Secondary immune response characteristics:
1. Faster response (reduced lag phase)
2. Increased affinity and specificity
3. Dominance of IgG production (not equal IgM and IgG)
4. Memory B cells and plasma cells are involved
Key differences from primary response:
1. IgG predominates over IgM
2. Higher antibody titers and longer persistence
3. Improved antibody affinity and specificity
4. Memory cells facilitate rapid response
Primary vs. Secondary Response:
Primary:
- Initial exposure to antigen
- Slow response (lag phase)
- IgM dominates initially, then IgG
Secondary:
- Subsequent antigen exposure
- Rapid response (reduced lag phase)
- IgG dominates from the start
This distinction is crucial for understanding:
1. Immune memory and vaccination
2. Antibody-mediated immunity
3. Immunological recall responses
Note: The secondary response is more efficient and effective due to immune memory cells, leading to better protection against infections.
39
Which immunoglobulin has the highest concentration?
IgG (70-75%)
40
IgG half-life in serum (days)
23 (21-25)
41
IgM half-life in serum (days)
6
42
IgA half-life in serum (days)
5
43
IgD half-life in serum (days)
1-3
44
IgE half-life in serum (days)
2-3
45
IgA in serum:
IgA in secretions:
IgA in serum: Monomer
IgA in secretions: Dimer
46
Sedimentation coefficient of IgG:
7s
47
Sedimentation coefficient of IgM:
19s
48
Sedimentation coefficient of IgA:
7s
49
Sedimentation coefficient of IgD:
7s
50
Sedimentation coefficient of IgE:
8s
51
Antibody produced in early immune response; opsonization; endotoxin neutralization; most primitive; also known as macroglobulin
IgM
52
IgM antibody most often formed in response to __________ bacteria:
Gram-negative (-) bacteria
53
What type of bond connects the H-H chain of a monomeric IgM?
Disulfide bond (S-S)
54
Major immunoglobulin in normal serum that can cross the placenta (passive immunity of newborn)
IgG
55
IgG subclass that is the most efficient in crossing the placenta:
IgG1
56
IgG subclass that does not cross the placenta:
IgG2
57
IgG subclass that is most efficient in complement fixation:
IgG3
58
IgG subclass that does not fix complement:
IgG4
59
Immunoglobulin that responds to carbohydrates antigens:
IgM
60
Immunoglobulin that responds to protein antigens:
IgG
61
How many disulfide bonds does IgG1 have?
2
62
How many disulfide bonds does IgG2 have?
4
63
How many disulfide bonds does IgG3 have?
15
64
How many disulfide bonds does IgG4 have?
2
65
Predominant immunoglobulin in secretions; present as dimer in secrations
IgA
66
A cell membrane immunoglobulin found on the surface of B lymphocytes in association with IgM; serves as immunoregulation; helps in the differentiation and maturation of B cell into plasma cell
IgD
67
Mediates some types of hypersensitivity reactions, allergies and anaphylaxis; is responsible for immunity to invading parasite; binds strongly to a receptor on mast cells and basophils with antigen, mediates the release of histamines and heparin from these cells
IgE
68
IgE was originally called ______.
REAGIN
69
Monoclonal antibodies was discovered by:
George Kohler and Cesar Milstein in 1975
70
True or False
The myeloma cell line that is chosen is capable of producing antibody and is also deficient of the enzyme HGPRT (hypoxanthine guanine phosphoribosyl transferase) and thymidine kinase which are needed for DNA synthesis:
False
The myeloma cell line that is chosen is INCAPABLE OF PRODUCING AN antibody and is also deficient of the enzyme HGPRT (hypoxanthine guanine phosphoribosyl transferase) and thymidine kinase which are needed for DNA synthesis
71
In hybridoma production, spleen cells are combined with myeloma cells in the presence of ____________ that fuses the cells, producing a hybridoma.
polyethylene glycol (PEG)
72
In hybridoma production, fused myeloma cells die because the pathway that makes DNA from new nucleotides is inhibited by ____________:
aminopterin
72
In hybridoma production, after fusion, cells are placed in culture using a selective medium containing _____________:
hypoxanthine, aminopterin, and thymidine (HAT)
73
Clinical applications of monoclonal antibodies
In vitro diagnostics:
1. Pregnancy testing (B-HCG)
2. Detection of tumor antigens
3. Measurement of hormones
74
Clinical applications of monoclonal antibodies
Therapeutic agents:
- Treatment for Rheumatoid arthritis and Crohn's antigens
- Metastatic breast CA
- Non-Hodgkin's Lymphoma
- Colorectal, head and neck CA
- Colorectal, non-small lung and breast cancers
- For treatment of SARS-CoV2 (in some cases)
- SARS-CoV2 neutralizing abs
