Consideration for alpha‐gal syndrome in two critically ill persons with group O blood who received group B plasma.

Background: The U.S. Centers for Disease Control and Prevention (CDC) has reported increasing rates of alpha‐gal syndrome, an allergic response after meat ingestion (AGS). AGS has been associated with prior exposure to tick bites or other biologics characterized by a life‐threatening immunoglobulin E (IgE)–mediated hypersensitivity to galactose‐alpha‐1,3‐galactose (alpha‐gal) an oligosaccharide structurally similar to the group B antigen on red blood cells (RBC) found in most non‐primate mammalian meat and products derived from these mammals. In 2023, Transfusion reported 3 group O recipients of group B plasma in the Washington, D.C. metropolitan area with no history of meat allergy who had anaphylactic transfusion reactions compatible with AGS. Aims: We investigated allergic reactions in 2 additional patients who received ABO minor‐incompatible blood products at 2 hospitals in the D.C. area during fall 2023. Methods: For both patients, a medical chart review was performed and IgE levels to alpha‐gal were measured. Results: The first patient, a 64‐year‐old, O‐positive patient status post heart transplant with no known allergies, was admitted with acute COVID‐19 induced antibody‐mediated transplant rejection and placed on extracorporeal membrane oxygenation (ECMO). While undergoing plasma exchange (PLEX) (50% albumin/50% fresh frozen plasma (FFP)), the patient tolerated 2 units of group O FFP and 1 unit of group A FFP before becoming hemodynamically unstable during transfusion of 1 unit of B‐positive FFP. PLEX was stopped. The patient later died of sepsis from underlying causes. The second patient, a 57‐year‐old O‐positive man with a history of melanoma and neuro fibromatosis type 1, was undergoing an abdominal resection including transfusion of 3 units of O‐positive RBC when he suffered hypotension and ventricular tachycardia requiring intraoperative code after receiving 2 units of group B FFP. Hiveswere noted after resuscitation. The patient had a history of tick bites but no known allergies. He is alive 5 months after the possible allergic event. Both patients had full transfusion reaction evaluations and immunology testing results above the positive cutoff for anti‐alpha‐gal IgE. Discussion and conclusion: Two patients with O‐positive blood and no known allergies experience danaphyl axis after transfusion with group B FFP. The symptoms cannot definitively be imputed to an allergic transfusion reaction, but the presence of IgE against alpha‐gal supports an association. Medicating patients with antihistamines and IV steroids pre‐transfusion may prevent allergic reactions. Restricting group B plasma‐containing products (plasma, platelets, cryoprecipitate) for patients who experience AGS‐like symptoms may be considered. [ABSTRACT FROM AUTHOR]