Allergen Quiz

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Questions and Answers

What is the primary mechanism involved in Type II hypersensitivity?

Antibody binding to self-antigens (correct)

Immune complex deposition

T-cell mediated cytotoxicity

T-helper cell activation

What type of hypersensitivity occurs rapidly after exposure?

Type II hypersensitivity (correct)

Type I hypersensitivity

Type III hypersensitivity

Type IV hypersensitivity

Which cytokine-related phenomenon is characteristic of delayed hypersensitivity reactions?

Direct cytotoxic action by antibodies

Activation of complement system

Release of cytokines hours after exposure (correct)

Immediate release of histamines

What type of antigen is considered a 'self' antigen?

Intrinsic antigen Signup and view all the answers

What is NOT a characteristic of Type II hypersensitivity?

It triggers acute allergic reactions Signup and view all the answers

After how long does the delayed phase of a Type II hypersensitivity reaction typically occur?

Several hours after exposure Signup and view all the answers

What distinguishes extrinsic antigens from intrinsic antigens?

They are acquired from exposure to foreign substances. Signup and view all the answers

Which of the following statements about antigens is true?

Extrinsic antigens can vary based on environmental exposure. Signup and view all the answers

Which type of antigen is not a natural part of the body's own cells?

Extrinsic antigen Signup and view all the answers

How are extrinsic antigens typically introduced to an organism?

Via exposure to foreign antigens Signup and view all the answers

What is the role of immunoglobulin E antibodies in relation to allergens?

They cause allergic diseases. Signup and view all the answers

How are allergic reactions characterized in terms of their onset?

They are acquired and rapid. Signup and view all the answers

What defines a substance as an allergen?

It can provoke a rapid immune reaction in sensitive individuals. Signup and view all the answers

Which statement accurately describes the nature of allergic reactions?

They require previous exposure to an allergen to occur. Signup and view all the answers

What is the primary type of antibodies produced in response to allergens?

Immunoglobulin E Signup and view all the answers

Which type of cells recognizes foreign cells in the immune response?

Macrophages and dendritic cells Signup and view all the answers

What is the primary role of B cells in response to a foreign antigen?

Producing antibodies Signup and view all the answers

Which cells act as antigen-presenting cells to trigger the B cell response?

Macrophages and dendritic cells Signup and view all the answers

What process is initiated due to the recognition of cells by macrophages or dendritic cells?

B cell response leading to antibody production Signup and view all the answers

In an immune response, the role of antigen-presenting cells is crucial for which type of cellular response?

Humoral response Signup and view all the answers

What type of immune response is triggered by specific allergens?

Type I hypersensitivity Signup and view all the answers

Which cells are primarily involved in the Th2 response during an allergic reaction?

CD4+ Th2 cells Signup and view all the answers

What substance is released during the degranulation of sensitized mast cells?

Histamine Signup and view all the answers

Which type of immunoglobulin is primarily involved in the immediate hypersensitivity reaction?

IgE Signup and view all the answers

What is the result of the late-phase allergic reaction that occurs 2–4 hours after exposure?

Release of cytokines Signup and view all the answers

How are mast cells and basophils activated during an allergic response?

By cross-linking IgE antibodies Signup and view all the answers

Which feature distinguishes IgE from other immunoglobulins in allergic reactions?

IgE binds to mast cell receptors Signup and view all the answers

What underlies the mechanism of sensitization in type I hypersensitivity?

Production of IgE and mast cell sensitization Signup and view all the answers

Which types of antigens can be identified by the immune system during the allergic response?

Both internal and external antigens Signup and view all the answers

What is the role of cytokines in the late-phase allergic reaction?

Regulate inflammation and recruit immune cells Signup and view all the answers

Study Notes

Allergens and Immune Response

An allergen is a substance that triggers an allergic reaction.
Individuals exposed to allergens may produce Immunoglobulin E (IgE) antibodies, leading to allergic diseases.
Allergic reactions are acquired, rapid, and occur upon re-exposure to specific antigens.

Mechanism of Allergic Reactions

Th2 Cells Activation: CD4+ Th2 cells stimulate IgE production from B cells.
Routes of Exposure: Allergens can enter the body via ingestion, inhalation, injection, or direct contact.
IgE Binding: IgE antibodies bind to receptors on the surface of mast cells and basophils during sensitization to allergens.

Types of Hypersensitivity

Type I Hypersensitivity:
- Characterized by rapid allergic reactions within minutes upon exposure to an allergen.
- Involves the degranulation of sensitized mast cells, releasing mediators like histamine and prostaglandins.
- Causes vasodilation, smooth muscle contraction, and can lead to various allergic responses.
Type II Hypersensitivity (Cytotoxic Hypersensitivity):
- Involves antibodies produced by the immune response binding to antigens on the surfaces of the body’s own cells.
- Antigens could be intrinsic (self-antigens) or extrinsic (foreign antibodies adsorbed during exposure).

Immune Response to Antigens

Macrophages or dendritic cells recognize and present the antigens to B cells.
This process triggers a B cell response, resulting in the production of antibodies against the foreign antigen.

Phases of Hypersensitivity Reactions

Immediate Phase: Occurs within minutes after exposure to an allergen.
Late Phase: Occurs 2–4 hours post-exposure, marked by the release of cytokines, contributing to prolonged inflammation and symptoms.

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Description

Test your knowledge on allergens and the immune response. This quiz covers the basics of how allergens cause reactions and the role of Immunoglobulin E in allergic diseases. Perfect for those studying biology or health sciences.