Anaphylactic Transfusion Reactions

Description 

Allergic transfusion reactions occur on a continuum of severity ranging from mild (urticarial) to moderate (anaphylactoid) to severe (anaphylactic). Anaphylactic transfusion reactions are severe allergic reactions characterized by profound hypotension and shock. Proposed causes include:

• recipient IgE or IgG antibodies to IgA in patients who have complete or partial (i.e., lack an isotopic or allotypic) IgA determinant
• recipient IgE or IgG antibodies to polymorphic forms of other serum proteins (IgG, haptoglobin, C4, etc.) in transfused donor blood
• recipient sensitization to various compounds, including drugs in donor blood, chemicals used to produce or sterilize IV tubing and plastic bags, and foodstuffs
• coincidental reaction to drugs or food taken prior to transfusion

Incidence

The incidence of anaphylactic transfusion reactions is very rare and unknown. There is no systematic collection of data. Reported incidences from individual studies vary widely.

Recent studies suggest that the risk of severe allergic reactions (anaphylactoid and anaphylaxis) in Canada is approximately 1/25,000 units for red cell transfusions and 1/1600 platelet pools. (See Kleinman S in Further Reading).