Immunology: Antigens and Antibodies

Questions and Answers

Which immunoglobulin is primarily involved in allergic reactions and binds to mast cells and basophils?

IgE (correct)

IgA

IgM

IgG

What percentage of the total immunoglobulin pool does IgD represent?

less than 1% (correct)

10%-15%

15%-20%

5%-10%

Which immunoglobulin is predominant in secretions such as tears and saliva?

IgE

IgA (correct)

IgM

IgD

What is the role of the Fc region of an antibody?

Mediates effector functions Signup and view all the answers

Which immunoglobulin has a pentameric form, making it a potent agglutinating antibody?

IgM Signup and view all the answers

What is the primary function of secretory IgA?

Prevents colonization by pathogens Signup and view all the answers

Which immunoglobulin mainly functions as a receptor on B cells?

IgD Signup and view all the answers

Which component of the antibody is responsible for binding to the antigen?

Fab Region Signup and view all the answers

What differentiates immunogens from antigens?

Immunogens are recognized as foreign and trigger an immune response. Signup and view all the answers

Which statement about antibodies is correct?

Antibodies recognize and bind to specific parts of antigens. Signup and view all the answers

Which of the following describes epitopes?

A single antigen can have multiple epitopes. Signup and view all the answers

What role do antigens play in the immune response?

Antigens stimulate the production of antibodies. Signup and view all the answers

What type of substances can be classified as antigens?

Food particles and dust. Signup and view all the answers

Why are antigens considered crucial for vaccine development?

Antigens trigger antibody production to defend against pathogens. Signup and view all the answers

Which characteristic applies to immunogens but not to all antigens?

Immunogens always trigger an immune response. Signup and view all the answers

What is a common source of antigens?

Components of viruses and fungi. Signup and view all the answers

What type of cells present antigens in the MHC-II pathway?

B-cells Signup and view all the answers

What is the unique characteristic of CD4+ T-cells?

They interact with MHC-II molecules. Signup and view all the answers

Which immunoglobulin class is most abundant in serum and plays a significant role in secondary immune responses?

IgG Signup and view all the answers

What describes the primary role of antibodies?

Serve as effector molecules in humoral immunity. Signup and view all the answers

How do CD8+ T-cells primarily recognize altered self-cells?

Via MHC-I molecules. Signup and view all the answers

In the context of immunoglobulin classes, what does IgA primarily do?

Provide defense at mucosal surfaces. Signup and view all the answers

What defines CD8+ T-cells' role in the immune response?

They become cytotoxic T lymphocytes targeting infected cells. Signup and view all the answers

What is the function of TH cells within the immune system?

Coordinate the immune response by signaling other cells. Signup and view all the answers

What is the concentration range of IgG in serum?

8-16 mg ml-1 Signup and view all the answers

Which immunoglobulin is known for being the first to be synthesized in a primary immune response?

IgM Signup and view all the answers

Which statement accurately describes the structure of IgM?

It is a pentamer with J-protein connections. Signup and view all the answers

What role does IgE play in the immune system?

It mediates allergic reactions and immunity against parasites. Signup and view all the answers

Which of the following statements about IgG is true?

It is the major antibody in secondary immune responses. Signup and view all the answers

What characteristic of IgM contributes to its effective complement activation?

Its pentameric structure. Signup and view all the answers

The multimeric nature of IgA is primarily important for which function?

Mucosal immunity. Signup and view all the answers

What is a common structure feature of all immunoglobulins?

They all are formed through genetic recombination. Signup and view all the answers

Which type of bond is characterized by the formation of hydrogen bridges between appropriate atoms?

Hydrogen Bonds Signup and view all the answers

What type of force arises from the interaction between electron clouds and hydrophobic bonds?

Van der Waals Forces Signup and view all the answers

What strengthens the bonding between antigens and antibodies?

Conformance of shapes Signup and view all the answers

What is the primary characteristic of monoclonal antibodies?

Highly purified from a single cell clone Signup and view all the answers

Which of the following techniques involves the combination of soluble antigen with soluble antibody to create visible complexes?

Precipitation reaction Signup and view all the answers

What is the main purpose of hemolysis testing?

To observe antigen-antibody reactions with a cellular indicator Signup and view all the answers

Which of the following accurately describes electrostatic forces?

Results from attraction between oppositely charged amino acids Signup and view all the answers

What does the agglutination process result in?

Larger aggregates of particulate antigens Signup and view all the answers

Study Notes

Antigens and Immunogens

Antigens are foreign substances that stimulate an immune response and can bind to antibodies.
All immunogens are antigens, but not all antigens are immunogens.
Key to triggering responses is the foreignness of antigens, which can include components from bacteria, viruses, fungi, and protozoa.
Example: Bacterial cell wall components are potent immunogens.

Antibodies

Antibodies are Y-shaped proteins produced by B cells that specifically recognize and bind to antigens.
Known as immunoglobulins, they play a crucial role in the humoral immune response.
Antigenic determinants, or epitopes, are specific parts of an antigen recognized by antibodies, and multiple epitopes can exist on a single antigen.

T-cells

Two main types of T-cells: Helper T-cells (TH) and Cytotoxic T-cells (TC).
TH cells (MHC-II restricted) send signals through cytokines to other immune system cells.
TC cells (MHC-I restricted) attack altered self-cells, such as infected cells.

Immunoglobulin Classes

Five classes of immunoglobulins: IgG, IgM, IgA, IgE, and IgD, each having unique structures and functions.
IgG is the most abundant immunoglobulin in serum, involved in secondary immune responses and crosses the placenta.
IgM is the first antibody produced in a primary response and is pentameric in structure, crucial for agglutination and complement activation.
IgA is predominantly found in mucosal areas and important for mucosal immunity, often in dimeric form.
IgE binds to mast cells and basophils, playing a role in allergic reactions and immunity against parasites.
IgD functions mainly as a receptor on B cells for activation.

Antibody Structure

Antibodies consist of two heavy chains and two light chains, with distinct Fab and Fc regions.
Fab region binds to the antigen, providing specificity, while Fc region mediates interactions with immune cells and effector functions.
Goodness of fit in antibody-antigen bonding is optimized by proximity and complementary shapes.

Antigen-Antibody Reactions

Various in-vitro tests detect antigen-antibody reactions:
- Agglutination: Particulate antigens aggregate in presence of specific antibodies.
- Precipitation: Combines soluble antigens with soluble antibodies to form visible insoluble complexes.
- Hemolysis testing: Measures cellular reactions to antigens and antibodies.
- ELISA: A method using enzyme-linked reactions for detection.

Monoclonal Antibodies

Monoclonal antibodies (MAbs) are purified antibodies derived from a single cell clone, offering high specificity for antigens.

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Description

This quiz explores the concepts of antigens and antibodies, focusing on their roles as immunogens. Understand the distinction between antigens and immunogens, as well as the foreignness required for an immune response. Test your knowledge on how these substances interact within the immune system.