16 Questions
What is the main characteristic of monoclonal antibody preparations?
They have a single type of antigen binding site, produced by a single B cell clone.
What is the term that refers to the strength of binding of a single epitope to a single antigen binding site?
Affinity
What is the impact of valence on the strength of binding?
It increases the strength of binding.
What is the term that refers to the cross-reactivity of antibodies with self-antigens?
Rheumatic fever
What is the primary function of neutralization in antibody functions?
Binding to pathogens and preventing them from infecting host cells.
Which of the following IgG subclasses is most effective for complement activation?
IgG3
What is the function of antibody-dependent cellular cytotoxicity (ADCC)?
Recruiting immune cells to eliminate infected or abnormal cells.
What is the percentage of total IgGs that are IgG?
80%
What is the primary function of immunoglobulins as membrane-bound molecules?
Act as antigen receptors
What is the characteristic of the constant region of heavy chains in immunoglobulins?
Constant amino acid sequence
What is the difference between allotypic and isotopic determinants?
Allotypic determinants are specific to each individual, while isotopic determinants are shared by all members of a species
What determines the strength of an antibody-antigen interaction?
The sum of multiple non-covalent bonds
What is the term for the specific regions of a given antigen recognized by a lymphocyte?
Antigenic determinants
What is the characteristic of idiotypic determinants?
They are located in the hypervariable regions of the antibody
What is the main difference between polyclonal and monoclonal antibodies?
Polyclonal antibodies are produced in response to multiple antigens, while monoclonal antibodies are produced in response to a specific antigen
What is the characteristic of the antibody structure?
It is dynamic and flexible
Study Notes
Immunoglobulins (Igs)
- Membrane-bound Igs act as antigen receptors, while soluble Igs participate in humoral immunity
- Igs have a heterogeneous structure, consisting of 2 identical light and 2 identical heavy chains
- Each heavy and light chain has a variable region (110 amino acids) and a constant region at the carboxy terminal
- Constant regions of heavy chains: μ, γ, δ, ε, α; light chains: κ, λ
Antibody Structure and Function
- Antibodies are flexible molecules that can bind to widely spaced or closely spaced cell surface determinants
- Isotypic determinants: antigenic determinants of constant regions that characterize classes and subclasses of heavy and light chains
- Allotypic determinants: slight variations in amino acid sequences in the constant regions due to allelic differences
- Idiotypic determinants: located in hypervariable regions, specific to antibodies with the same antigenic specificity
Antigen-Antibody Interactions
- Antigenic determinants: specific regions of a given antigen recognized by a lymphocyte
- Antibody-antigen complex is more stable than individual structures
- Quantitating antibody-antigen interactions: strength is determined by the sum of multiple non-covalent bonds
- Affinity refers to the strength of binding of a single epitope to a single antigen binding site
- Avidity: influenced by both affinity and valence of interaction (number of interacting binding sites)
Poly- and Monoclonal Antibodies
- Polyclonal antibodies: complex mixtures of different antibodies produced by many B cell clones
- Monoclonal antibodies: homogeneous preparations produced by a single B cell clone
Antibody Functions
- Neutralization: binding to pathogens to prevent infection
- Opsonization: marking pathogens for destruction by phagocytes
- Complement activation: triggering the complement system to lyse pathogens
- Agglutination: clumping together pathogens for removal
- Antibody-dependent cellular cytotoxicity (ADCC): recruiting immune cells to eliminate infected or abnormal cells
IgG Functions
- Most common Ig class (80% of total Igs)
- IgG1, IgG3, and IgG4 can cross the placenta
- IgG3 is most effective for complement activation
This quiz covers the structure and functions of immunoglobulins, including their role in humoral immunity, and the different types of heavy and light chains.
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