Allergic Flashcards
What are the 4 clinical features of bronchial asthma
1) Acute attacks of SOB- acute airway obstruction due to contraction of smooth muscle
2) Mucus hypersecretion
3) Airway inflammation
4) Bronchial hyper-responsiveness
Name some of the common triggers for asthma
- Allergens
- Chemical irritants
- Dust/ smoke
- Post exercise
- Post coughing
- Post hyperinflation
- Viral colds
Name the 2 phases of asthma
1- Bronchospasm/ early phase
2- Inflammation- late phase
What bronchial hyper-responsivness
A state characterised by easy bronchospasm
How is bronchial hyper-responsivess monitored?
- Assessed with bronchial challenge test
- Uses spaspogens such as histamine and metacholine to assess bronchospasm
3 histological changes seen in asthma
- Goblet cell hyperplasia
- Thick sub basement membrane
- Cellular infiltrate
What signals the B cells to switch to produce IgE
First signal: IL-4, IL-13
Second signal: when CD14 on B cells bind to its ligand on T cells
What does IgE bind to when it circulates in the blood?
- High affinity IgE receptors on mast cells (Fc-epsilon-RI)
- Low affinity receptors on lymphocytes, eosinophils, platelets and macrophages
What does the mast cell release once activated
Histamine
Leukotriene
Cytokines
What causes acute obstruction in asthma?
Inhaled allergen
Via histamine and leukotriene
Constrics smooth muscle
Where do eosinophils originate
Bone marrow
What interleukins regulate eosinophils
IL-3, IL-5
What mediates terminal differentiation of eosinophils?
GM-CSF
IL-5
Eosiophils are a rich source of…
Leukotrienes
Which cell contains proteins that damage airway epithelium and increase bronchial hyper responsiveness
Eosinophils
Which interleukin prolongs survival of eosinophils
IL-5
Which drug may be useful in immunotherapy for asthma in the future, and briefly state its MoA
Reslizumab
- anti IL-5 so reduces eosinophil levels
What develops on lymphocytes following allergen inhalation in human
Surface activation markers
Is TH1 associated with protective immunity, or allergic diseases (asthma etc)
Protective- TH2 is associatedd with allergic disease
Name 4 factors favouring a Th1 phenotype (protective)
- Presence of older siblings
- Early exposure to day care
- TB, measles or hep A infection
- Rural environments
Name 5 factors favouring the Th2 phenotype
- Widespread abx use
- Western lifestyle
- Urban environment
- Diet
- Sensitisation to house dust mites/ cockroaches
