Immunology Lecture 4 Quiz

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Questions and Answers

What is the primary function of B cells in the immune response?

Identify pathogens through phagocytosis

Produce cytokines

Present antigens to T cells

Differentiate into plasma cells and produce antibodies (correct)

Which type of immunity is characterized by immediate, non-specific responses?

Innate immunity (correct)

Adaptive immunity

Auto-immunity

Tolerance immunity

What occurs when B cells encounter their specific antigen?

They directly attack pathogens

They undergo apoptosis

They produce antibodies and become memory cells (correct)

They activate T cells

Which immunoglobulin class is primarily responsible for long-term immunity?

IgG Signup and view all the answers

What do T cell receptors specifically bind to?

Specific antigens presented by antigen presenting cells Signup and view all the answers

What is the role of memory B cells in the immune system?

To provide rapid response upon subsequent exposures to the same antigen Signup and view all the answers

Which component of the immune system is involved in recognizing polysaccharide antigens?

T-independent B cells Signup and view all the answers

What type of immune response is largely influenced by helper T cells?

Antibody-mediated immunity Signup and view all the answers

Which type of antibody is primarily involved in allergic responses?

IgE Signup and view all the answers

What is the primary function of the constant region (Fc) of an antibody?

Elicit different immune responses Signup and view all the answers

How do antibodies enhance phagocytosis?

By marking pathogens for digestion by mediators Signup and view all the answers

What is the structure of an antibody composed of?

Two heavy and two light chains Signup and view all the answers

What role do antibodies play in the complement system?

Enhance the innate immune response Signup and view all the answers

Which of the following effects do antibodies have on viruses?

Prevent them from entering host cells Signup and view all the answers

What type of response is characterized by macrophages and neutrophils engulfing pathogens?

Phagocytosis Signup and view all the answers

Which immunological role do antibodies NOT play?

Directly destroying pathogens Signup and view all the answers

Study Notes

Immunology Lecture 4 Outcomes

Basic anatomy of the immune system (L1):
- Organs involved in immune function
- Cells of the immune system and their basic functions
  - Basic white blood cell functions
  - T and B cell-specific functions
  - Antigen-presenting cells
Immune responses (L2-L6):
- Innate immunity
  - Non-specific immunity
- Adaptive immunity
  - Cell-mediated immunity
  - Antibody-mediated immunity
External defenses (L8):
- (Not detailed, only listed)
Immune-related pathology (L7-L8):
- Cancer
- Allergy
- Hypersensitivity
- Auto-immune disorders
- Transplant rejection
- HIV

Adaptive Immunity: Lymphocytes & Antigens

Antigen: Molecule triggering a specific immune response.

Lymphocytes & Receptors

B cells: Have B-cell receptors (BCRs) that bind specific antigens.
T cells: Have T-cell receptors (TCRs) that bind specific antigens.
Antigens: T-independent (polysaccharides) or T-dependent (proteins)

B Lymphocytes

Differentiation: B cells differentiate into plasma cells.
Function: Produce antibodies.
Memory cells: Some B cells become memory cells for a faster response in future exposures.

B Lymphocytes Produce Antibodies

Plasma cells: Produce antibodies.
Memory cells: Some B cells become memory cells for future faster responses.
Antibody classes: Five types of immunoglobulins (Ig): IgG, IgA, IgM, IgE, IgD.

Antibodies

Structure: Y-shaped proteins with two identical antigen-binding fragments (Fab).
Function: Identify and neutralize pathogens.
Classes:
- IgM: Important in primary immune responses.
- IgA: Found in mucosal secretions (saliva, milk).
- IgG: Most abundant antibody; crosses the placenta.
- IgE: Involved in allergic reactions.
- IgD: Functions as a B-cell receptor.
Locations: Attached to B cells; free in plasma; secreted by plasma cells.

Antibodies: Hinder Invaders/Pathogens

Neutralization: Prevents pathogens from entering host cells.
Agglutination: Clumping pathogens, making them easier for phagocytes to engulf.
Precipitation: Forms insoluble complexes that are easily removed.

Antibodies & Innate Responses: Complement System

Activation: Initiated by antibodies binding to pathogens.
Membrane attack complex: Forms pores in pathogens, leading to lysis.

Antibodies & Innate Responses: Phagocytosis

Opsonization: Antibodies tagging pathogens for phagocytic cells.
Phagocytes: Engulf pathogens (e.g., macrophages, neutrophils).

Antibodies & Innate Responses: NK Cells

Antibody-dependent cellular cytotoxicity (ADCC): NK cells recognize and kill antibody-coated pathogens.

Antibody Specificity

Diversity: Huge number of different foreign molecules.
Specificity: Each B cell responds to only one antigen.
Clonal selection: B cells with the correct receptor proliferate and differentiate into plasma cells.

Antibody Specificity: Primary & Secondary Responses

Primary response: First exposure to an antigen, slower response.
Secondary response: Second exposure to the same antigen, faster and more potent response.

Antibodies: Active vs Passive Immunity

Active immunity: Production of antibodies through exposure.
Passive immunity: "Borrowed" immunity; antibodies from another source.

Vaccination

Louis Pasteur: Developed the anthrax vaccine.
Mechanism: Attenuated/weakened bacteria to reduce virulence.

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Description

Test your knowledge on the anatomy and functions of the immune system as discussed in Immunology Lecture 4. This quiz covers aspects such as innate and adaptive immunity, various immune responses, and pathology related to the immune system. Perfect for students looking to reinforce their understanding of immunology concepts.