Anaphylaxis Flashcards
What type of cell causes anaphylactic symptoms?
Mast cells
What binds to mast cells?
IgE
What are the main signalling molecules involved in anaphylaxis?
Histamines and leukotrienes which are found in mast cell granules
What do histamines act on?
Blood vessels and smooth muscle
What affect does histamines have on blood vessels?
In connective tissue - Causes the dilation of blood vessels leading to increased blood flow to the surface, and increased movement of fluid out the blood steam
In mucosa - causes constriction of airways and contraction of the smooth muscle in the walls of the intestine
What causes mast cell degranulation?
When the circulating antigen binds to the IgE which is bound to the mast cell via Fc receptor, this causes receptor cross linking leading to degranulation
How are IgE produced?
The CD4 T helper cells causes a class switch to IgE production
What is an allergen?
An antigen which causes an allergic type IgE-mediated response
What causes rashes and puffy skin seen in anaphylaxis?
Histamine causes vasodilation leading to red skin colour and oedema leading to raised appearance
What is skin rash called?
urticaria
When can the localised skin reaction seen in allergy be useful?
In skin prick tests to see if they caused a wheal-and-flare reaction
What is hay fever called?
Allergic Rhinitis
What causes Allergic Rhinitis?
Odema in the epithelia lining the nose resulting in general irritation and stimulation of mucus secretion
What causes asthma?
When the allergen reaches he bronchioles of the lungs, resulting in contraction of smooth muscles which reduces the diameter of the airways, leads to increased mucus production and difficulty breathing in and out
What causes food allergies?
When an allergen is ingested, it acts on the mucosal mast cells in the intestinal tract - leading to vomiting and diarrhoea
if absorbed into blood stream, can cause rashes or itching
