SEMINAR: Mediators of Human Anaphylaxis: New insights on the mechanisms behind severe allergic reactions

Anaphylaxis is a severe allergic reaction commonly triggered by foods, insect stings or medication. At its most severe, anaphylaxis can cause life-threatening hypotension (very low blood pressure) or hypoxia (loss of oxygen supply to the body). As anaphylaxis is generally an unanticipated event requiring treatment in the Emergency Department (ED), the mediators released by the immune system that contribute to the severity of such reactions are very difficult to study.

The Emergency Department Anaphylaxis (EDA) Study collected blood samples from patients presenting with anaphylaxis to 8 EDs across Australia. Blood levels of 17 different immune mediators were measured to determine if they were increased during anaphylaxis and if these increases correlated with reaction severity. Levels of 5 immune mediators (histamine, mast cell tryptase, IL-6, IL-10 and TNFRI) were shown to be elevated during anaphylaxis. Interestingly, levels of these mediators correlated with the occurrence of hypotension in the most severe cases but not with hypoxia, suggesting different immune mechanisms may trigger the different symptoms of anaphylaxis.