Hypersensitivity Flashcards
Give 5 clinical manifestations of TI hypersensitivity
Urticaria Angioedema Anaphylaxis Asthma Food allergy Allergic rhinitis
Give four things released by mast cells and their roles.
Tryptase (remodels CT matrix)
Histamine (Increased vasc perm, toxic to parasites, smooth muscle contraction)
LTCD/D4/E4 (increase vasc perm, smooth muscle contraction, stimulate mucous secretion)
Platelet Activating factor (attracts WBCs, activates neutrophils, eosinophils and platelets and amplify production of lipid mediators)
Name 3 different sequelae of binding of IgG or IgM to cell bound antigens in a type II Hypersensitivity Reactions
Complement activation (HDN and transfusion reaction) ADCC (ITP, AIHA and goodpastures syndrome) Antibody mediated cellular dysfunction
Give some approaches to treatment of type II hypersensitivity.
Anti-inflammatory drugs (complement activation)
Plasmapheresis
IVIG
Splenectomy
What is the time frame for type II hypersensitivity?
5-12 hours
What is the old friends hypothesis and biodiversity hypothesis?
Give some conditions associated with poor microbiota.
Western lifestyle induces alteration of the symbiotic relationship with parasites and bacteria leading to dysbiosis of the microbiome in the gut
Crohn’s Autism Colorectal cancer Obesity TIDM
Give two generic places mast cells are found.
Connective tissue surrounding blood vessels
Mucosal and epithelial tissues of gut respiratory tract skin etc.
How does mast cell degranulation occur?
What is another way in which a mast cell may degranulate?
IgE binds to Fcereceptor on mast cells - sensitised.
Allergen causes IgE cross linking to occur leading to release of granule contents and synthesis of new mediators.
Direct activation of mast cell via Irritants and C3a and C5a complement proteins.
How do you describe a urticaria rash?
Papules with erythematous base - remember to describe where on the body also.
Give some CNS signs of anaphylaxis.
Give 3 GI signs.
Lightheadedness
Loss of consciousness
Headache
Anxiety
Vomiting
Diarrhoea
Abdo pain
Give four ways in which adrenaline aids in the treatment of anaphylaxis.
Peripheral vasoconstriction
Reversal of airway obstruction and bronchospasm
Increase the force of myocardial contraction
Inhibits mast cell activation.
How might you treat them abnormal adaptive immune response against the allergens?
How might you counteract the mast cell activation?
Anti-IgE mABs - Omalizumab
Allergen desensitisation - oral immunotherapy
Anti-histamine
LTRA
Corticosteroids
Which T cell is involved in Type I hypersensitivity reactions?
TH2 cells.
What is the hygiene hypothesis?
Children exposed to animals, pets and microbes in the early post-natal period seem to be protected against certain allergic diseases.
What is responsible for anaphylaxis?
Allergen absorbed into systemic circulation.
