Type 1 Hypersensitivity Flashcards
Gove an overview of type 1 hypersensitivity
• Immunological basis for different diseases o Different organs affected
• Immediate reaction (<30min)
o Local reaction : Ingested or inhaled allergen
o Systemic reaction: Insect sting or IV administration
• Antigens (allergens)
o Environmental, non-infectious antigens (proteins)
What are examples of allergens for type 1 hypersensitivity
• Seasonal exposure
o Tree and grass pollens
• Perennial exposure
o House dust mite
o Animal dander = cats and dogs o Fungal spores
• Accidental exposure
o Insect venom (wasp and bee stings)
o Medicines - for example, the antibiotic penicillin o Chemicals such as latex
o Foods: milk, peanuts, nuts, etc…
What are type.1 Czechia is s
• Abnormal adaptive immune response against the allergens
o T helper 2 (TH2) response (IL-4, IL-5, IL-13) o IgE production
• Mast cell activation
o Sensitized individuals
o Different clinical allergic disorders depending of on mast cell location
What is the hygiene hypothesis
“Hygiene hypothesis”
• Children exposed to animals, pets and microbes in the early postnatal period appear to be protected against certain allergic diseases
How does the westestrn lide associate witht Days iOS is
Old friends hypothesis” or “biodiversity hypothesis”
• Western lifestyle induces alteration of the symbiotic relationships with parasites and bacteria leading to “dysbiosis” of the microbiome at mucosal surfaces (gut)
What is dysbiosis
Dysbiosis = compositional and functional alterations of microbiome
What is microbiome
Microbiome = The complete genetic content of all the microorganisms that typically inhabit in the body, such as the skin or the gastrointestinal tract.
Describe teh origins and sitribion f Mach ells
Strategic location
• Most mucosal and epithelial tissues = gastrointestinal tract, skin, respiratory epithelium
• In connective tissue surrounding blood cell
Only differentiate i tissue - due to scf. Immune responses against parasites -ge bind - mast cells - recruit eosinophils - mast cells t mucosal surface. If you activate mast cells - sued against host??? Mast cells in close proximity to blood vessels - impact on patient
What are some mast cell mediators
Ss, Mast cells release mediators which Acton the vasculature, SM, CT, mucous hands and inflam cells. Tryptase, histamine, leukotrieen, PAF
Describe the immune mechanism o allergic reaction
First encounter - nothing happens - host just produce ige. But ige binds mast cells on the surface. When the patient is reexposed, ige is already there. Allergen will crossling the immunoglobiluns - mast cels get degranulated. Close to blood vessels - increased vascular permeability. Vasodilation. In lung, bronchoconstriction
What is urticaria
Itchy red flare, realised itchy swelling. Mast cells activation within epidermis.
Caused by mast cell activation within the epidermis
Mediators = Histamine and leukotrienes/cytokines
If prolonged and chronic exposure = atopic dermatitis and eczema.
No longer than 24 h - if it is than a inferential cause
What s angioedema
Non itchy swelling
Caused by mast cell activation in the deep dermis.
Mediators = Histamine and bradykinin
lip, eyes, tongue and upper respiratory airways
What are the systemic manifisetsions of allergic reaction
In blood stream - all mast cells in body activated. SS.
Within its 10 min, blood vessel reduce by 30%.. bronchoconstriction
Hypotension Cardiovascular collapse Generalized urticaria Angioedema
Breathing problems
Descrbe the treatment of anaphylactic shock
IM epinephrine (adrenaline)
Act on specific receptors to reverse the effects of mast cells
• Reverses peripheral vasodilation and reduces oedema and alleviates hypotension
• Reverses airway obstruction / bronchospasm
• Increases the force of myocardial contraction
• Inhibits mast cell activation
www.medscape.com
DO NOT DELAY TREATMENT!!!!
Monitor pulse, blood pressure, ECG, oximetry
• Timesaver vs lifesaver
• IM vs SC administration
• Multiple doses may be required
• Proper use of epipen
Wha are some ige mediated allergic reactions
Ss
