What is the pathophysiology of an allergic transfusion reaction?

Updated: Jan 12, 2021
  • Author: S Gerald Sandler, MD, FCAP, FACP; Chief Editor: Emmanuel C Besa, MD  more...
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Allergic reactions typically present as rash, urticaria, or pruritus and are indistinguishable on examination from most food or drug allergies. Allergic reactions are IgE mediated. These reactions are usually attributed to hypersensitivity to allogeneic proteins in plasma, on leukocytes or platelets or, uncommonly, soluble allergens found in the transfused blood component. Anaphylactic reactions have been reported to be associated with anti-IgA in recipients who are IgA deficient. [20] However, while anaphylactic reactions do occur, uncommonly, the link to anti-IgA is not regarded as evidence based. [21]

Patients with congenital haptoglobin deficiency, typically of Northeast Asian origin, may experience anaphylactic nonhemolytic transfusion reactions when transfused with conventional blood components. [22, 23] Patients with hereditary C1-inhibitor deficiency may have recurrent attacks of angioedema when transfused with standard plasma-containing blood components. [24]

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