Immunology - Hypersensitivity of Allergic Disease Flashcards
What are the Gel and Coomb’s classification?
Type I: immediate hypersensitivity Type II: Direct cell killing Type III: Immune complex mediated Type IV: Delayed type hypersensitivity Slide 5
What is an allergy immunologic-ally?
IgE-mediated antibody response to external antigen. Slide 8
What could be a reason for the prevalence of allergy increasing?
The ‘hygiene hypothesis’
The world is too clean due to improved sanitation and decreased incidence of infectious disease. Slide 12
If a child is exposed to more antigens earlier on in their life then what tends to happen to the TH2 cells as the child develops?
They decrease and there is predominantly more TH1 cells which results in allergies. Slide 13
What environment would result in a child still having predominantly Th2?
Lack of Th1 differentiation stimuli:
Only child
Urban environment
Don’t get early daycare exposure. Slide 14
What are some clinical features of Type I allergic disease?
Occurs quickly after antigen exposure More than one organ involved Can be influenced by cofactors e.g. exercise May present with: Athma Anaphylaxis Diarrhoea/vomiting Angioedema. Slide 15
What cells are involved in allergic disease?
B cells, Th2 cells, mast cells, eosinophils and basophils. Slide 16
What do the Th2 cells do in an allergic response?
Releases IL-4, 5 and 13.
IL-4, 5, 13 activated B cells to produce IgE.
IL-4, 13 activate mast cells.
IL-5 stimulates differentiation of eosinophils. Slide 17
What is the role of mast cells in allergic reactions?
Express receptors for the Fc region on the IgE antibody (heavy chain)
Allows these antigen specific IgE antibodies to stay on circulating mast cells. Slide 19
What happens when mast cells with IgE antibodies on their Fc receptors comes into contact with the allergen again?
Causes instant degranulation of mast cell releasing vasoactive mediators. Slide 20
What specific investigations can be done to identify an allergy?
Skin prick test
Challenge test
Quantitate specific IgE to putative allergen.
Slide 30
What evidence can you test during an acute anaphylactic episode?
Serum tryptase levels due to mast cell degranulation. Slide 30
What management can be done of IgE mediated allergic disorders?
Stop mast cell activation Prevent effects of mast cell activation Anti-inflammatory agents Management of anaphylaxis Immunotherapy. Slide 32
What drugs can be used to block mast cell activation?
Sodium cromoglycate, topical spray for prophylaxis. Slide 33
What drugs can be used to prevent effects of mast cell activation?
Anti-histamines and leukotriene receptor antagonists e.g. montelukast.
Slide 34+35
