Urticarial Reactions
PATHOPHYSIOLOGY: A basic understanding of hypersensitivity is all that you need to understand urticarial reactions.
These reactions are essentially always an IgE-mediated immediate (type I) hypersensitivity reaction in response to a previously seen allergen. Let me explain.
I'm no immunologist (and I don't play one on TV), but type I hypersensitivity is manifested by the production of IgE in response to exposure to a foreign antigen. In this case, the antigen (better termed an "allergen" in this case) is usually a protein or other substance. The recipient is exposed through one method or another (transfusion or simply by seeing the allergen in nature), and IgE is formed. The next time the allergen is seen, IgE cruises into the area and starts the chain of events that leads to a type I hypersensitivity reaction, including binding of IgE-allergen complexes to mast cells and/or basophils, with resultant release of histamine. This substance is the cause of the itching and rash seen in these reactions.
Let's go on and discuss the treatment of the urticarial reaction.
Back to Urticarial Reactions
Back to Transfusion Reaction Types