α-Gal sensitization was first described in 2009. It occurs when individuals develop IgE antibodies against the common mammalian disaccharide galactose-α-1,3-galactose (α-Gal), which is often triggered by tick bites. A retrospective national study in France from 2022 to 2024 found that severe allergic reactions were higher in group O recipients transfused with group B or AB platelets and plasma compared to other ABO combinations, which led to the hypothesis that α-Gal sensitization in group O recipients could be contributing to these severe allergic transfusion reactions. α-Gal is immunogenically similar and cross-reactive with the blood group B glycan. Recently, researchers in France grouped 59 platelet and plasma transfusion recipients who had severe allergic transfusion reactions (grade > 2) into three categories—group O recipients who received B or AB platelets or plasma (Group 1; n=12), group O recipients who received A plasma or platelets (Group 2; n=4), and all remaining recipients (Group 3; n=43). All patients were then tested for the presence of anti-α-Gal IgE antibodies of which 67% of Group 1 patients had high titers compared to zero in Group 2. In addition, 7% (3/43) of recipients in Group 3 had high titers of anti-α-Gal IgE antibodies, all of which were group O recipients who received group O products. Further investigations in other geographic regions are needed to confirm these observations, and care should be taken transfusing group O patients with incompatible plasma and platelets.
References:
- Malard L, Beuscart C, de Chaisemartin L, de la Taille V, Delettre F, Humbrecht C, Dunbar N, Lecam S, Laperche S, Tiberghien P; Biomedical Excellence for Safer Transfusion (BEST) Collaborative. Association between group B major ABO-incompatible platelet or plasma transfusion and severe allergic reactions: A nationwide haemovigilance analysis suggesting a role for α-gal syndrome. A Biomedical Excellence for Safer Transfusion Collaborative study. Vox Sang. 2026 Jan;121(1):81-86. doi: 10.1111/vox.70136. Epub 2025 Oct 29. PMID: 41161810.
- de Chaisemartin L, de la Taille V, Nicaise-Roland P, Malard L, Beuscart C, Gouel-Chéron A, Laperche S, Tiberghien P. Severe allergic transfusion reactions to group B/AB plasma or platelets in group O recipients are linked to α-Gal sensitization. Blood. 2026 Jun 18;147(25):3113-3117. doi: 10.1182/blood.2025032045. PMID: 41949618.
- van Nunen S. Ticks and transfusions: a potentially fatal mix! Blood. 2026 Jun 18;147(25):2999-3000. doi: 10.1182/blood.2026033810. PMID: 42313439.
