Mild Allergic (Urticarial) Transfusion Reactions

Description

Urticarial transfusion reactions are generally mild allergic reactions thought to be caused by pre-existing recipient IgE antibody to proteins in the plasma of the transfused blood component

Other possible causes include:

• donor plasma contains IgE antibody to an allergen in the recipient plasma
• coincidental reaction in atopic recipients
• coincidental reaction to drugs or food to which the recipient has been exposed before or during the transfusion

Usually a specific allergen or definitive cause is not identified and reactions characterized by hives and itching are designated as "allergic" even though their precise origin is unknown.

Allergic transfusion reactions occur on a continuum of severity. When bronchospasm and laryngeal edema are present, the allergic reactions are often called anaphylactoid. When severe hypotension and shock occur, the reaction is designated as anaphylactic. These more severe types of allergic reactions are discussed in the anaphylactic section.

Incidence

Mild allergic (urticarial) transfusion reactions are the most common type of transfusion reactions, occurring in about 1-3% of transfusions of plasma-containing components.