Blood Transfusion Reactions More Likely in Alpha-Gal Syndrome Hotspots
A retrospective cohort study found that in U.S. regions with high prevalence of alpha-gal syndrome, type O blood recipients who received B or AB platelet or plasma units had nearly four times the risk of allergic transfusion reactions compared with those given O units. No such increased risk was seen in low-prevalence regions. The findings suggest a newly recognized risk called transfusion-related alpha-gal syndrome.
Alpha-gal syndrome arises from tick bites, primarily the lone star tick, and triggers delayed allergic reactions to mammalian meat. The alpha-gal carbohydrate closely resembles the blood group B antigen, causing cross-reactivity. In this study, type O recipients in high-prevalence regions faced a nearly fourfold higher risk of allergic transfusion reactions when given B or AB plasma or platelets, while low-prevalence regions showed no such effect. The absolute risk remains small, but the findings point to a newly recognized transfusion-related complication that may warrant regional blood-banking adjustments.
This finding could reshape transfusion protocols in tick-dense U.S. regions, prompting blood banks to prioritize type O units for O recipients even in emergencies. Patients with AGS or unknown sensitization may face added, though rare, allergic risks. Clinicians may need to weigh unit availability against potential reactions, and public awareness of tick-borne allergies could grow. However, the negligible absolute risk suggests practice changes will be measured, not urgent, with broader implications for regional blood supply management and tick-disease surveillance.