Allergy and angioedema Flashcards
What is hypersensitivity?
Inappropriate immune response to an otherwise harmless organisms
How is hypersensitivity mediated?
Antibodies or T cells
What kind of organisms can hypersensitivity reactions be against?
Environmental agents
Self antigens
Infectious agents
How can hypersensitivity reactions be classified?
Type I, II, III, IV
What mediates immediate (type I) hypersensitivity reactions?
Mast cells
What immunoglobulin is associated with mast ells and so type I hypersensitivity?
IgE
What mediates type II hypersensitivity?
What is the effect of this?
IgM or IgG antibodies react against cell surface or ECM antigens
Causes opsonisation and phagocytosis of cells, complements and leukocyte activation
What mediates type III hypersensitivity reaction?
What is the effect of this?
Immune complexes of circulating antigens and IgM or IgG antibodies
Causes complement recruitments and activation of leukocytes (macrophages and neutrophils)
What mediates type IV hypersensitivity reaction?
What is the effect of this?
CD4 and CD8 T cells
CD4 cells cause macrophage activation and inflammation
CD8 cells cause direct target cell killing and inflammation
What hypothesis describes why allergies are increasing?
Hygiene hypothesis - living in a cleanse world, reduced infection, increased immunisation, less exposure to microbiome
What characteristics of environmental agents make them good at causing hypersensitivity reactions?
Small - can be absorbed through lungs, skin, eye, mouth
Aeroallergens - in the air (pollen, dust mite, fungi)
Foods
Drugs
Venom
Describe a type I hypersensitivity reaction?
IgE mediated degranulation of mast cells causing release of histamine, lysosomal enzymes and proteases
What are some clinical consequences fo allergic reactions?
Swelling, rash
Contraction of airways
How can a type I hypersensitivity reaction be diagnosed?
History - did they have the symptoms - wheezing, rash, swelling
How long after the exposure did it occur - should be within seconds but some drugs can slow this down.
Did the reaction reoccur when re-exposed
Does it occur seasonally?
Do the symptoms go away when avoiding the allergen
How can the allergen be detected?
Skin prick test - salt water - histamine - expected allergen Observe the reactions to each
In what scenario may you not be able to do skin prick test?
Eczema
Heavily covered in tatoos
If skin prick tests are not suitable to detect an allergen what can be used?
Blood tests
Specific monoclonal antibody is added to a plate with the patients blood serum, add an anti-igE antibody to cause colour change if it has bound
What equipment often used in dental practice can cause type I hypersensitivity reaction?
Latex allergy
If a patient doesn’t know they are allergic to latex how can you tell?
History - problems with balloons, condoms, gloves, kiwi, banana, pineapple
How can latex allergy be diagnosed?
Skin prick test
specific IgE blood test
Challenge test
Where can latex be found in the dental practice?
Gloves Dam Gutte percha amalgam carriers protective eye wear
Other than latex what are some common allergies in dental practice?
Formaldehyde - disinfectant for RCT
LA
Chlorhexidine
Antibiotics
What are the guideline software anaphylaxis?
Sever allergic reaction with 1 or both of:
breathing difficulties
hypotension
What should you do if a patient has anaphylaxis?
Administer adrenaline
Give antihistmaine
Keep patient lying flat to allow blood circulation to head
