Current understanding of allergic transfusion reactions: incidence, pathogenesis, laboratory tests, prevention and treatment

Abstract

Non-haemolytic transfusion reactions are the most common type of transfusion reaction and include transfusion-related acute lung injury, transfusion-associated circulatory overload, allergic reactions, febrile reactions, post-transfusion purpura and graft-versus- host disease. Although life-threatening anaphylaxis occurs rarely, allergic reactions occur most frequently. If possible, even mild transfusion reactions should be avoided because they add to patients' existing suffering. During the last decade, several new discoveries have been made in the field of allergic diseases and transfusion medicine. First, mast cells are not the only cells that are key players in allergic diseases, particularly in the murine immune system. Second, it has been suggested that immunologically active undigested or digested food allergens in a donor's blood may be transferred to a recipient who is allergic to these antigens, causing anaphylaxis. Third, washed platelets have been shown to be effective for preventing allergic transfusion reactions, although substantial numbers of platelets are lost during washing procedures, and platelet recovery after transfusion may not be equivalent to that with unwashed platelets. This review describes allergic transfusion reactions, including the above-mentioned points, and focusses on their incidence, pathogenesis, laboratory tests, prevention and treatment.

Fig. 1

Allergen-dependent and -independent pathways and mast cell-mediated and basophil-mediated sub-pathways in the murine immune system. The allergen-dependent pathway is triggered when allergens bind to antibodies that are bound by FcRs expressed on mast cells and basophils. Subsequently, activated mast cells and basophils release chemical mediators. The allergen-independent pathway is triggered when biological response modifiers (BRMs) bind to their respective receptors expressed on mast cells and basophils, which results in the activation of these cells. In the allergen-dependent mast cell-mediated sub-pathway, IgE and FcεR come into play and histamine is released. In contrast, in the allergen-dependent basophil-mediated sub-pathway, IgG and FcγRs come into play and platelet-activating factor (PAF) is released. Neutrophils and monocytes are reported to be other key players in allergy. IgG and FcγRs are involved and PAF is released.