228 The availability and need for an in-vitro assay to implement a mitigation strategy for allergic transfusion reactions

Introduction/Objective Severe allergic and anaphylactic reactions should generally be managed by allergen avoidance. The basophil activation test is well described as an in-vitro method to identify allergens via mast cell responsiveness to allergen exposure and monitor medication effectiveness for allergic reaction prevention. However, this test is not widely available due to lack of appreciation of its full clinical potential in identifying the cause of anaphylactic transfusion reactions. Methods/Case Report The clinical courses of three patients with severe to fatal allergic transfusion reactions in one hospital who were managed without test availability are described to illustrate the potential utility of this test in clinical practice. Results A thalassemia major transfusion-dependent patient experienced repeated severe allergic reactions to Red Blood cells unsuccessfully mitigated with washed Red Blood Cells. Eventually a trial of directed donors abstaining from fish consumption one week prior to donation prevented transfusion reactions. A group O liver transplant candidate with a known cat allergy experienced a fatal transfusion reaction to group B Plasma from a donor with pet cats. It remains unknown whether the reaction was due to group B substance or the major cat allergen, fel D 1, but had he survived, identifying the allergen would have been critical for future transfusion support. A blood group O patient with myelodysplastic syndrome and a 96 unit transfusion history experienced 3 severe allergic reactions to only group A Plasma and Platelets before the pattern was identified. Conclusion Transfusion reactions due to group A or group B substances and inhaled or ingested antigens are underrecognized. Patients are experiencing repeated or fatal reactions due to lack of a readily available in-vitro test to identify the allergen. The basophil activation test is well described and increased availability could guide mitigation strategies such Blood Group A and B substance avoidance, or allergen-free components from directed donors.