Immunoglobulins and Antibodies

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Questions and Answers

What is the main characteristic of monoclonal antibody preparations?

They are produced in the laboratory and have multiple binding sites.

They are only produced in response to viral infections.

They consist of complex mixtures of different antibodies produced by many different B cell clones.

They have a single type of antigen binding site, produced by a single B cell clone. (correct)

What is the term that refers to the strength of binding of a single epitope to a single antigen binding site?

Valence

Avidity

Antigenicity

Affinity (correct)

What is the impact of valence on the strength of binding?

It increases the strength of binding. (correct)

It decreases the strength of binding.

It has no effect on the strength of binding.

It is only relevant for multivalent antigens.

What is the term that refers to the cross-reactivity of antibodies with self-antigens?

Rheumatic fever Signup and view all the answers

What is the primary function of neutralization in antibody functions?

Binding to pathogens and preventing them from infecting host cells. Signup and view all the answers

Which of the following IgG subclasses is most effective for complement activation?

IgG3 Signup and view all the answers

What is the function of antibody-dependent cellular cytotoxicity (ADCC)?

Recruiting immune cells to eliminate infected or abnormal cells. Signup and view all the answers

What is the percentage of total IgGs that are IgG?

80% Signup and view all the answers

What is the primary function of immunoglobulins as membrane-bound molecules?

Act as antigen receptors Signup and view all the answers

What is the characteristic of the constant region of heavy chains in immunoglobulins?

Constant amino acid sequence Signup and view all the answers

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 Signup and view all the answers

What determines the strength of an antibody-antigen interaction?

The sum of multiple non-covalent bonds Signup and view all the answers

What is the term for the specific regions of a given antigen recognized by a lymphocyte?

Antigenic determinants Signup and view all the answers

What is the characteristic of idiotypic determinants?

They are located in the hypervariable regions of the antibody Signup and view all the answers

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 Signup and view all the answers

What is the characteristic of the antibody structure?

It is dynamic and flexible Signup and view all the answers

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

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Description

This quiz covers the structure and functions of immunoglobulins, including their role in humoral immunity, and the different types of heavy and light chains.