Allergy and Lung Regulation Quiz

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Questions and Answers

Which immunoglobulin is primarily involved in Type I hypersensitivity reactions?

IgD

IgM

IgA

IgE (correct)

IgG antibodies are primarily produced at the onset of an infection.

False

What substance is predominantly released during a Type I hypersensitivity reaction?

Histamine

IgA is expressed in _______ tissue and helps protect the neonatal gut.

mucosal Signup and view all the answers

Match the following immunoglobulins with their primary functions:

IgG = Highly specific antibodies targeting single epitopes IgA = Protects the neonatal gut and is expressed in mucosal tissue IgM = Circulating tetramers made at the beginning of infection IgE = Implicated in allergy and response to parasitic threats IgD = Induces antibodies in B cells and activates basophils and mast cells Signup and view all the answers

What is the hormone released by sympathetic nerve fibres?

Noradrenaline Signup and view all the answers

Parasympathetic stimulation causes relaxation of airway smooth muscle.

False Signup and view all the answers

Which neurotransmitter is involved in parasympathetic regulation of airway smooth muscle?

Acetylcholine Signup and view all the answers

Beta-2 adrenergic receptors cause ______ of smooth muscle and bronchodilation.

relaxation Signup and view all the answers

Match the types of anti-muscarinics to their descriptions:

Short-acting anti-muscarinics = E.g., ipratropium bromide Long-acting anti-muscarinics = E.g., tiotropium Signup and view all the answers

What initiates a type II hypersensitivity reaction?

Previously formed antibodies reacting with antigens on host cell membranes Signup and view all the answers

Goodpasture syndrome involves the lungs as one of its primary organs affected.

True Signup and view all the answers

What antibodies are usually involved in type II hypersensitivity reactions?

IgG or IgM Signup and view all the answers

The primary antigen causing Goodpasture syndrome is the _____ subunit of type IV collagen.

Alpha-3 Signup and view all the answers

Match the outcomes of complement activation in Type II hypersensitivity with their effects:

Cell lysis = Myasthenia Opsonisation and phagocytosis = Autoimmune hemolysis Neutrophil activation and tissue damage = Anti-GBM disease Metabolic activation = Graves’ disease Signup and view all the answers

Which of the following is an example of a Type II hypersensitivity reaction?

Haemolytic disease of the newborn Signup and view all the answers

Type II hypersensitivity primarily involves the kidneys and heart.

False Signup and view all the answers

What type of hypersensitivity reaction is Anti-Glomerular Basement Membrane (aGBM) disease?

Type II Signup and view all the answers

The main components of the glomerular basement membrane include type _____ collagen.

IV Signup and view all the answers

What functional activity occurs in Type II hypersensitivity?

Metabolic activation Signup and view all the answers

Signup and view all the answers

Study Notes

Allergy, Hypersensitivity, and the Lung

Sympathetic Regulation:
- The sympathetic nervous system regulates the "fight-or-flight" response.
- A hormone released by sympathetic nerve fibers is noradrenaline.
- Noradrenaline activates adrenergic receptors.
- Two types of adrenergic receptors are alpha and beta.
- Airway smooth muscle cells have beta adrenergic receptors.
- Sympathetic stimulation of beta-2 receptors on airway smooth muscle causes muscle relaxation and bronchodilation.
- Activation of beta-2 receptors causes muscle relaxation by activating adenylate cyclase, increasing cyclic AMP.

Parasympathetic Regulation

Neurotransmitter: The neurotransmitter released by post-synaptic parasympathetic nerve fibers to regulate airway smooth muscle is acetylcholine.
Effect on Smooth Muscle: Parasympathetic stimulation causes smooth muscle constriction.
Receptors: Acetylcholine acts on muscarinic receptors (M1-5), specifically the M3 subtype, on smooth muscle cells.
Anti-muscarinics: Anti-muscarinics block parasympathetic activity by blocking receptors, such as M3 receptors.
Types of Anti-muscarinics: Different types of anti-muscarinics exist.

Hypersensitivity Types and Descriptors

Type I:
- Mediated by IgE antibodies, resulting in an immediate response (within 1 hour).
- Examples include anaphylaxis, hay fever, and asthma.
- Triggered when an antigen binds to IgE antibodies attached to mast cells or basophils, causing the release of mediators like histamine, leading to inflammation.
Type II:
- Cytotoxic hypersensitivity, involving antibodies (IgG or IgM) targeting the host's own cells or foreign cells.
- Outcomes depend on complement activation and cell metabolism.
- Examples include autoimmune diseases like Graves' disease and Goodpasture's disease or Rh incompatibility.
Type III:
- Immune complex hypersensitivity, where antibodies combine with antigens to form immune complexes that deposit in tissues.
- This triggers inflammation, such as in serum sickness or hypersensitivity pneumonitis.
Type IV:
- Cell-mediated hypersensitivity, involving T cells and cytokines.
- Mediated by a delayed response (2-3 days).
- Examples include contact dermatitis, the tuberculin skin test, and tissue rejection.

Antibodies Description

Antibodies are produced by B-lymphocytes (plasma cells).
Their role is to neutralize or eliminate pathogens.
Five types of antibodies exist: IgG, IgA, IgM, IgE, and IgD.
IgG: mononmers highly specific for single epitopes.
IgA: found in mucosal tissues, protecting the neonatal gut.
IgM: circulating tetramers produced at the beginning of an infection.
IgE: linked to parasitic threats and allergies, often in conjunction with eosinophils.
IgD: monomers involved in the activation of mast and basophil cells.

Hypersensitivity Type I

Initiation: Antigen interaction with IgE bound to mast cells or basophils.
Timing: Immediate (within 1 hour).

Hypersensitivity Type I Reactions

Examples: Anaphylaxis, allergies (food, drugs, pollens, pet dander), and allergic bronchial asthma.

Hypersensitivity Type II

Mechanism: Antibodies (IgG or IgM) binding to antigens on host-cell membranes, leading to cell destruction.

Hypersensitivity Type III

Mediation: Formation of antibody-antigen complexes.
Antibody Types: Mainly IgG or IgM.
Precipitates: Immune complexes are deposited in various tissues (e.g., skin, joints, vessels, glomeruli).
Pathway Triggered: Classical complement pathway.
Outcome: Triggers inflammation due to complement activation and recruitment of inflammatory cells, like monocytes and neutrophils).

Hypersensitivity Type IV

Mediators: T-cells releasing cytokines (e.g., IL-2, IFN-γ).
Requirement: Primary sensitization to the antigen is needed.
Delay: 2-3 days.
Consequences of Macrophage Failure: Macrophages may fuse to form giant cells, leading to granuloma formation where they can't destroy the pathogen.

Examples of hypersensitivity Type IV Reactions

Contact dermatitis, Tuberculosis skin test, tissue rejection

Case Studies (Specific examples from the provided texts)

Case 1 (Type I): 18-year-old male experiencing anaphylaxis to peanuts.
Case 2 (Type II): 45-year-old female with haemoptysis due to Anti-Glomerular Basement Membrane disease.
Case 3 (Type III): Hypersensitivity pneumonitis caused by inhaled antigens (e.g., from moldy hay).
Case 4 (Type IV): 53-year-old man with sarcoidosis potentially due to a reaction to mycobacteria.

Treatments for Hypersensitivity Pneumonitis

Removal of the triggering antigen, and if needed immunosuppression.

Diagnosing Hypersensitivity Pneumonitis

Mantoux/Tuberculin skin test. (Detailed steps for test procedure are provided in the text.)

Diagnostics of Hypersensitivity reactions (more general information):

Details on what types of antigens and antibodies are associated with each type of hypersensitivity reaction are in the text.

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Description

Test your knowledge on the dynamic regulation of airway smooth muscle by the sympathetic and parasympathetic nervous systems. This quiz covers aspects such as adrenergic and muscarinic receptors, as well as the associated neurotransmitters and hormones involved in respiratory physiology.