The following is a short review of research recently published in the New England Journal of Medicine:
Vadas et al, "Platelet-Activating Factor, PAF Acetylhydrolase, and Severe Anaphylaxis" NEJM Vol. 358:28-35 January, 2008 Number 1. For further information about this study, please contact the Allergen Bureau.

Platelet-activating factor (PAF) is an important mediator of anaphylaxis in animals, and interventions that block PAF have been shown to prevent fatal anaphylaxis. This study is the first to investigate the roles of PAF and PAF acetylhydrolase, the enzyme that inactivates PAF, in anaphylaxis in humans.

The authors measured serum PAF levels and PAF acetylhydrolase activity in 41 patients who had previously had an anaphylaxic reaction and in 23 control patients. Serum PAF acetylhydrolase activity was also measured in 9 patients with peanut allergy who had fatal anaphylaxis and compared with that with a number of different control groups including non-allergic patients (adults and children), plus children with mild peanut allergy, patients with non-fatal anaphylaxis, children who had died of non-anaphylactic causes, and children with either life-threatening or non–life-threatening asthma.

Serum PAF levels were directly correlated and serum PAF acetylhydrolase activity was inversely correlated with the severity of anaphylaxis. PAF acetylhydrolase activity was significantly lower in patients with fatal anaphylactic reactions to peanuts than in patients in any of the control groups. Failure of PAF acetylhydrolase to inactivate PAF may contribute to the severity of anaphylaxis. The researchers believe that this study may eventually lead the way to developing methods of predicting who are most at risk of experiencing mild to severe anaphylaxis, and also creating some kind of treatment, such as enzyme replacement therapy.

They also stressed that further studies on this are needed as there may well be other chemicals released by the body that play a role in anaphylaxis.