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Questions and Answers
Which statement correctly describes the structure of Secretory IgA?
Which statement correctly describes the structure of Secretory IgA?
Which immunoglobulin type is known for binding to basophils and mast cells without requiring antigen binding?
Which immunoglobulin type is known for binding to basophils and mast cells without requiring antigen binding?
What is a significant property of IgA concerning its role in immune response?
What is a significant property of IgA concerning its role in immune response?
Which light chain type is NOT a subtype of lambda chains?
Which light chain type is NOT a subtype of lambda chains?
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Which immunoglobulin class is primarily associated with local immunity and is found in bodily secretions such as tears and saliva?
Which immunoglobulin class is primarily associated with local immunity and is found in bodily secretions such as tears and saliva?
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Which immunoglobulin class is primarily associated with mucosal immunity?
Which immunoglobulin class is primarily associated with mucosal immunity?
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What unique structure does IgM possess that distinguishes it from other immunoglobulin classes?
What unique structure does IgM possess that distinguishes it from other immunoglobulin classes?
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Which immunoglobulin subclass is known for its ability to fix complement?
Which immunoglobulin subclass is known for its ability to fix complement?
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What is the major immunoglobulin found in serum, responsible for systemic immunity?
What is the major immunoglobulin found in serum, responsible for systemic immunity?
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Which immunoglobulin class is primarily involved in allergic reactions?
Which immunoglobulin class is primarily involved in allergic reactions?
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Which of the following describes the subclass IgG4?
Which of the following describes the subclass IgG4?
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Considering antibody subclasses, which of the following pairs are correctly matched?
Considering antibody subclasses, which of the following pairs are correctly matched?
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What is the primary function of immunoglobulins?
What is the primary function of immunoglobulins?
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What characteristic feature allows IgG to cross the placenta?
What characteristic feature allows IgG to cross the placenta?
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Which of the following describes the structural components of a typical immunoglobulin molecule?
Which of the following describes the structural components of a typical immunoglobulin molecule?
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Immunoglobulin classes include which of the following?
Immunoglobulin classes include which of the following?
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What distinguishes myeloma proteins from regular immunoglobulins?
What distinguishes myeloma proteins from regular immunoglobulins?
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Which immunoglobulin class is primarily involved in allergy responses?
Which immunoglobulin class is primarily involved in allergy responses?
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What is the secondary interaction of antibodies that aids in dealing with large antigens?
What is the secondary interaction of antibodies that aids in dealing with large antigens?
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In which scenario is the concentration of immunoglobulins particularly significant for diagnosis?
In which scenario is the concentration of immunoglobulins particularly significant for diagnosis?
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Which characteristic is NOT true about antibodies?
Which characteristic is NOT true about antibodies?
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Which region of the immunoglobulin is primarily responsible for variable diversity?
Which region of the immunoglobulin is primarily responsible for variable diversity?
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What is the significance of the theory of clonal selection in antibody synthesis?
What is the significance of the theory of clonal selection in antibody synthesis?
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What determines the unique specificity of an antibody?
What determines the unique specificity of an antibody?
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Which statement accurately reflects the role of the framework regions in immunoglobulins?
Which statement accurately reflects the role of the framework regions in immunoglobulins?
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What aspect of immunoglobulin genetic coding was established by Dryer and Bennett in 1965?
What aspect of immunoglobulin genetic coding was established by Dryer and Bennett in 1965?
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What was a significant finding made by Susumu Tonegawa in the late 1980s regarding immunoglobulin genes?
What was a significant finding made by Susumu Tonegawa in the late 1980s regarding immunoglobulin genes?
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Which type of antibody response occurs upon the first exposure to an antigen?
Which type of antibody response occurs upon the first exposure to an antigen?
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Which of the following best describes idiotype determinants of immunoglobulins?
Which of the following best describes idiotype determinants of immunoglobulins?
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Which statement accurately describes the difference between an antigen and an immunogen?
Which statement accurately describes the difference between an antigen and an immunogen?
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Which immunoglobulin class is primarily responsible for the secondary immune response?
Which immunoglobulin class is primarily responsible for the secondary immune response?
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What are haptens when referring to antibodies?
What are haptens when referring to antibodies?
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Which of the following correctly identifies the difference between isotype, idiotype, and allotype?
Which of the following correctly identifies the difference between isotype, idiotype, and allotype?
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In terms of B-cell activation, what are the primary phases of an antibody response?
In terms of B-cell activation, what are the primary phases of an antibody response?
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How do affinity and avidity differ in the context of antibody-antigen interactions?
How do affinity and avidity differ in the context of antibody-antigen interactions?
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What characteristic primarily differentiates major histocompatibility complex (MHC) class I from class II?
What characteristic primarily differentiates major histocompatibility complex (MHC) class I from class II?
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What is the primary role of monoclonal antibodies in immunology?
What is the primary role of monoclonal antibodies in immunology?
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What primarily characterizes T-independent antigens?
What primarily characterizes T-independent antigens?
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Which of the following is a feature of Freund’s Complete Adjuvant?
Which of the following is a feature of Freund’s Complete Adjuvant?
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Which of the following components recognizes and binds to pathogen-associated molecular patterns (PAMPs)?
Which of the following components recognizes and binds to pathogen-associated molecular patterns (PAMPs)?
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Which factor does NOT influence the immunogenicity of antigens?
Which factor does NOT influence the immunogenicity of antigens?
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What is the primary consequence of the interaction between double-stranded RNA and TLR-3?
What is the primary consequence of the interaction between double-stranded RNA and TLR-3?
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What type of antigens are primarily recognized by T cells?
What type of antigens are primarily recognized by T cells?
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Which option describes a critical feature of haptens?
Which option describes a critical feature of haptens?
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Which of the following best defines superantigens?
Which of the following best defines superantigens?
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What is the role of adjuvants in an immune response?
What is the role of adjuvants in an immune response?
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How does the size of an immunogenic determinant impact its recognition by T cells?
How does the size of an immunogenic determinant impact its recognition by T cells?
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What does the presence of haptens primarily indicate about the immune response?
What does the presence of haptens primarily indicate about the immune response?
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Which of the following correctly describes MHC molecules?
Which of the following correctly describes MHC molecules?
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What can be concluded about the structural aspects of immunogens?
What can be concluded about the structural aspects of immunogens?
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What type of response is elicited by T-dependent antigens?
What type of response is elicited by T-dependent antigens?
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Study Notes
Antigens and Antibodies
- Antigens are substances that elicit an immune response.
- Immunogens are macromolecules that trigger an adaptive immune response.
- An antigen can be combined with an antibody or T-lymphocyte receptor.
- Haptens are low molecular weight molecules.
- They can bind to antibodies but to stimulate a specific immune response, a carrier is needed.
- Antigens that are easily phagocytosed are generally more immunogenic.
- Immunogenicity is determined by foreignness, molecular size, chemical composition, and degradability.
- Immunogenicity is also influenced by host genotype, and dose and route of administration and presence of adjuvants
- Epitopes are the specific regions on an antigen that are recognized.
- MHC, or human leukocyte antigens (HLAs), are major histocompatibility complex.
- Learning objectives for the chapter include defining terms, comparing characteristics of MHC classes, differentiating immunoglobulin classes, and describing IgG molecular structure.
Antigen Characteristics
- Immunogens are macromolecules capable of triggering and reacting with antibodies.
- Any substance capable of binding to an antibody or T-cell receptor.
- Haptens are low-molecular weight molecules needing a carrier to trigger an immune response.
Antigen vs. Immunogen
- Antigens are any substance that can bind to antibody or T cell receptor.
- Immunogens are any substance that can elicit an immune response.
- All immunogens are antigens but not all antigens are immunogens. Hapems are not immunogens.
Epitope
- Epitopes, also known as antigenic determinants, are regions of an antigen.
- They are recognized by antibodies or T cells.
- Proteins can have multiple epitopes.
Histocompatibility Antigens
- MHC molecules are known as human leukocyte antigens (HLA).
Immunogenicity of Antigens
- Determined by factors such as foreignness, molecular size, chemical composition, and degradability.
- Influenced by host genotype, dose and route of administration, and the presence of adjuvants.
Adjuvants
- Substances mixed with antigens to enhance immunogenicity.
- They prolong antigen persistence and increase the antigen's size and susceptibility to processing and presentation.
- Aluminum potassium sulfate (alum) is an example.
- Freund's adjuvants (incomplete and complete) are examples.
- These are used when antigens are poorly immunogenic.
Chemical Nature of Immunogens
- Proteins, polysaccharides, nucleic acids, and lipids (some glycolipids and phospholipids) can be immunogenic.
- Proteins and some lipids are immunogenic for T cells.
Types of Antigens
- T-independent antigens have a polymeric structure and activate polyclonal B cells.
- T-dependent antigens are primarily proteins. They are processed and presented to helper T cells.
Antigenic Determinants
- Recognized by B cells and antibodies: Composition (proteins, polysaccharides, nucleic acids, haptens), sequence determinants, and conformational determinants.
- Size: 4-8 residues.
- Recognized by T cells: Proteins (some lipids), sequence determinants, and processed (MHC presentation).
- Size: 8-15 residues.
- Number: Limited to those that can bind to MHC.
Comparison of Antigen Recognition
- B cells bind to antigens through immunoglobulin (Ig) molecules directly, with no need for MHC.
- T cells bind to processed antigens that are presented on MHC molecules.
Superantigens
- Substances binding to the Vβ domain of T cells.
- Examples include staphylococcal enterotoxins, toxic shock toxin, exfoliating toxin, and streptococcal pyrogenic exotoxins.
Determinants Recognized by the Innate Immune System
- PAMPs: Pathogen-Associated Molecular Patterns
- PRRs: Pattern Recognition Receptors
Immunoglobulins/Antibodies
- Immunoglobulins (Igs) are glycoprotein molecules
- They are produced by plasma cells
- They act as antibodies, in response to a foreign substance.
- They combine with corresponding antigens.
- Some are isolated in the gamma globulin fraction of protein.
- Igs are heterogeneous. Myeloma proteins are homogenous.
- Basic structure involves heavy and light chains.
Antibody Structure
- Typical immunoglobulin molecule are composed of heavy and light chains.
- There is a Fab (fragment, antigen-binding) segment and a Fc segment.
Immunoglobulin Classes
- IgM, IgG, IgA, IgD, and IgE
Human Immunoglobulin Classes
- IgG, IgM, IgA, IgD, and IgE are the classes of human immunoglobulins.
- Each class has different heavy chains.
Human Immunoglobulin Subclasses
- IgG1, IgG2, IgG3, IgG4
- IgA1, IgA2 are subclasses of IgA
Antibody Synthesis
- Primary antibody response has a lag period.
- Secondary antibody response (anamnestic) has a faster response and a higher antibody level.
Antibody Specificity and Diversity
- Antibody specificity is based on Jerne and Burnet's clonal selection that suggests specificity is a genetically predetermined characteristic of B cells.
- Constant and variable portions of antibody chains are coded by separate genes.
- Specific Ig segments are selected and joined during B-cell maturation.
Clonal Selection
- Each B cell has a B cell receptor (BCR) specific for an antigen
- Antigen, binding to the specific BCR, causes proliferation and differentiation into plasma cells.
Monoclonal Antibodies
- Produced from a single B-cell clone
- Used to detect or treat certain cancers and other diseases. Myeloma and hybridoma cells are fused to produce them.
Multiple Myeloma (MM)
- Plasma cell cancer with multiple bone lesions.
- Unknown cause, potentially due to radiation, obesity.
- Results in overproduction of M protein (paraprotein).
- Diagnosed by:
- Bleeding;
- Platelet abnormalities, tall sharp peaks and localized band on serum/urine electrophoresis.
- Monoclonal serum protein detection. IgG common, IgA less common, IgD rare.
- Bence Jones protein in urine.
Quantification of Antibodies
- Methods to measure antibody levels (IgG, IgM, IgA):
- Radial immunodiffusion
- Nephelometry
- Turbidimetry
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Description
This quiz covers the essential concepts related to antigens and antibodies, including their definitions, functions, and immunogenicity. Explore key terms such as haptens, epitopes, and MHC, as well as the differences between immunoglobulin classes. Test your knowledge on the adaptive immune response fundamentals.
