Allerfy Flashcards
What is a hypersenstivity reaction?
An antigen specific immune respose that are either inapproiate or excessive and result in harm to the host using the normal immune response
What is a type 1 hypersentivity reaction?
An allerfic reaction that is mediated by IgE
What mediates type -4 hypersensitvity reactions?
Type 2 or anitbody mediated by IgG or IgM, type III or immune complex mediated is IgG or IgM, TType IV or cell mediated is again by IgG or Igm
Why is the hygine hypothesis?
That the different exposures in a less sterile environment, such as a farm make the body less likley to get a immune response
What is Atopy?
The genetic predispostion to produce IgE against other antibodies, meaning that allergy is more likley in children with parents who have allergy
What are the different cells involved in allergic and non allergic responses?
In allergic there are TH1 phenotypes, and there are TH2 phenotypes and IgE production in allergic reponses
What is clincal cross reactivity and give some examples?
This is where if you have a allergy to one substance you are more likley to become allergic to another substance, is seen for example a person who is allergic to cows milk has a 92% chance of being allergic to goats milk
What are some of the features of mast cells>
Healing, large nucleus and cytoplas and lots of granules that have a role in the acute phase inflammatory response
What is the role of mast cells in the allergic resposne?
Follwoing the binding of IgE all the stuff within the granules is realeased and therefore causes the symptoms
What are the roles of th cyotkine IL-4 and IL-12,?
Are involved in stimulating and amplyfying the TH2 response
What are the role of the cytokines IL03 and Il-5?
They promote eosinophil production and activation
What is the role of TNF-a?
Promotes inflammtorym stimulates the cytokine production and activates the endothiael cells
What are the role of the lipid mediator leukotrienes C4, D4 and E4?
Cause smooth muscle contraction, increase vascular pentration
What is the role of the lipid mediator platlet acticvating facto>
Attractleukocaues,a nd amplifies the production of lipid mediators and activates the neutophils and the eospinophils
What happens on the first exposure to a new antigen>
The plasma cells produce an antigen specific IgE which can bing the mast cells
What happens on the second exposure to a new antigen?
Antigen, cross links with IgE on the cell surface, and this triggers the realease of granule contents such as histamin and chemokines, and the systntehis of new mediators such as leukotriens, causing increased vascular permeability, vasodilation, and brochioal constriction
What is urticia and how does it occur?
Is a skin manifestation of an allergic reactions, caused by the mast cells in the epidermis, causes the increased vascular permebaulity and vascoiation, and there is a highly raised rash,
What are some of the cases of anigodema?
Mast cells within the deep epidermis, lips eyes and tongues and upper airwayd bedome swollen, and this is caused by the increase in vascular permeability
What is anahylaxis?
A systmeic manifestation of an allergic response and activation of mast cells
What causes anaphylaxis?
Vasodilation, increased vascular permeability and brochoconstriction
What happens in anaphylaxis?
There is hypotension and cirsulatory collaspe and generalised utriticia
Why does adrenaline used as a treatment for anyaphylacitic shock?
It reduces the periphral vasodilation, reduces the odema, and elviated the hypotension, and reverese the airway obstruction and increases the force of myocardial obstruction
What would you look for in a clincial history for allergy?
Seasonaility route of exposure allergens and any atopy
What would some of the blood tests that you would perform when diagnosing allergy be?
Serum allergen specific IgE, skin prick teste (wheal and flare rash) challenge tests in food and drink allergy, and serum mast rypase
What are some of the drugs that you would use in management of an allergy?
Anti IGE, anayphylasic, cortiocsteriods and antihistmaine
What are the principles other than drugs of allergen managment?
Education (espeically of schools and patients) and allergen avoidance and elimation
What is the proccess of allergen desenstisation?
Adminstration of increases doses of allergen extracs due over a period of years in most succsful in cases that are realting to insect venom
