Alpha-Gal syndrome (AGS) is an acquired allergic reaction caused by IgE antibodies against galactose-α-1-3-galactose (alpha-Gal), a carbohydrate expressed by most mammals but not humans. Bites from certain tick species, Amblyomma americanum (lone star tick) in the U.S., can stimulate the production of these antibodies. Many alpha-Gal antibodies cross-react with the human blood group B-antigen, and allergic transfusion reactions (ATRs) have…