Hypersensitivity and the Lung

Question 1

Autonomic NS

Answer 1

Sympathetic ganglion - within a chain adjacent to the spinal cord.
Parasympathetic ganglion - within or very close to effector organ.

Question 2

Parasympathetic bronchconstriction

Answer 2

Vagus nerve neurons terminate in the parasympathetic ganglia in the airway wall.
Short nerve fibres reach the muscle and release ACh.

Question 3

Antimuscarinics

Answer 3

Ipratropium bromidev- can be used as an inhaled treatment to relax airways in asthma and COPD - but short acting antimuscarinic.

Question 4

LAMAs

Answer 4

Long action - increase bronchodilation and relieve breathlessness in asthma and COPD.

Question 5

Sympathetic regulation

Answer 5

Activation of beta2 receptors on airway smooth muscle - muscle relaxation.

Question 6

SABA and LABAs

Answer 6

Short-acting (salbutamol) and long acting (formoterol) beta2 agonists.
Given with steroids for asthma and without for COPD.
Acute rescue of bronchoconstriction.

Question 7

Adverse effects of B2-agonists

Answer 7

Tachycardia
Hyperglycaemia - loss of insulin sensitivity - increased liver glucose release.

Question 8

Hypersensitivity

Answer 8

Type I - IgE antibodies - immediate - Anaphylaxis, Hayfever.
Type II - Cytotoxic, Antibodies bound to cell antigen - hours to days -Transfusion reactions.
Type III - Deposition of immune complexes - Typically 7 – 21 days - Hypersensitivity pneumonitis; lupus; post streptococcal Glomerulonephritis.
Type IV - T-cells (lymphocytes) - Days to weeks or months - Tuberculosis;
Stevens-Johnson syndrome.

Question 9

Antibodies

Answer 9

IgM: Circulating tetramers made at the beginning of infection.
IgG: Monomer highly specific antibodies targeting single epitopes.
IgE: Likely to have developed in response to parasitic threats. Implicated in allergy, particularly alongside eosinophils
IgA: Expressed in mucosal tissue. Forms dimers. Protects the neonatal gut (expressed in breast milk).
IgD: Monomers, induction of antibodies in B cells, activates basophils and mast cells.

Question 9

Type 1

Answer 9

Antigen interacts with IgE bound to mast cells or basophils.
Degranulation of mediators lead to local effects.
Histamine the predominant mediator.

Question 10

Anaphylaxis

Answer 10

GIVE ADRENALINE

Question 11

Type II

Answer 11

Antibodies reacting with antigenic determinants on the host cell membrane.
Usually IgG or IgM.
Outcome depends on whether complement is activated and if metabolism of cell is affected.

Question 12

Type III

Answer 12

Antigen-immunoglobulin complexes are formed on exposure to the allergen.
These are deposited in tissues and cause local activation of complement and neutrophil attraction.

Question 13

Type IV

Answer 13

T-cell mediated, releasing IL2, IFᵧ and other cytokines.
Requires primary sensitisation.
Secondary reaction takes 2-3 days to develop.
May result from normal immune reaction – if macrophages cannot destroy pathogen, they become giant cells and form granuloma.