Urticaria
Assessment Question * A 56 year old man is referred to your allergy clinic with a 2 year history of daily urticaria and intermittent angioedema. He has not seen any benefit from standard dose antihistamines and has been placed on long term prednisolone to control his symptoms.
In this document I will aim to cover the following issues pertaining to the Case history given above. 1. What is the mechanistic difference between allergic and non-allergic urticaria. 2. I will detail my approach to investigating the underlying cause of the daily urticaria and intermittent angioedema in this patient given the limited information. 3. I will provide a short discussion on why I have chosen to use an experimental treatment agent. 4. I will characterise the effectiveness of this agent and evidence to obtain continued funding of the treatment.
Mechanistic difference between allergic and non-allergic urticaria.
Urticaria is a dermal oedema resulting from vascular dilation and leakage of fluid into the skin in response to mediators released from skin mast cells namely histamine and proteases. The activation of mast cells is a complex process that can be initiated by various signals often through specific mast cell surface receptors (1).
The mechanisms by which mast cells are activated and induce chronic urticaria is not fully understood, however they can separated into immunological and non-immunological (2).
IgE mediated allergic urticaria is , also known as a Type 1 hypersensitivity and is initiated by antigen/allergen binding to mast cell surface bound IgE leading to cross linking on the surface of mast cells and basophilis thus causing degranulation with histamine release (3).
Non allergic urticaria can be mediated by an auto immune response. Essentially auto-immune responses result from the binding of IgG autoantibodies to IgE and or to the IgE Fc receptors themselves on Mast Cells. These auto immune urticarias account for up to 50% of patients
In this document I will aim to cover the following issues pertaining to the Case history given above. 1. What is the mechanistic difference between allergic and non-allergic urticaria. 2. I will detail my approach to investigating the underlying cause of the daily urticaria and intermittent angioedema in this patient given the limited information. 3. I will provide a short discussion on why I have chosen to use an experimental treatment agent. 4. I will characterise the effectiveness of this agent and evidence to obtain continued funding of the treatment.
Mechanistic difference between allergic and non-allergic urticaria.
Urticaria is a dermal oedema resulting from vascular dilation and leakage of fluid into the skin in response to mediators released from skin mast cells namely histamine and proteases. The activation of mast cells is a complex process that can be initiated by various signals often through specific mast cell surface receptors (1).
The mechanisms by which mast cells are activated and induce chronic urticaria is not fully understood, however they can separated into immunological and non-immunological (2).
IgE mediated allergic urticaria is , also known as a Type 1 hypersensitivity and is initiated by antigen/allergen binding to mast cell surface bound IgE leading to cross linking on the surface of mast cells and basophilis thus causing degranulation with histamine release (3).
Non allergic urticaria can be mediated by an auto immune response. Essentially auto-immune responses result from the binding of IgG autoantibodies to IgE and or to the IgE Fc receptors themselves on Mast Cells. These auto immune urticarias account for up to 50% of patients
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