Anaphylaxis studies are notoriously difficult to do for both practical and ethical reasons. Anaphylaxis is a very serious allergic reaction that generally requires a trip to the emergency room. Anaphylaxis can also be deadly.
So, I was very interested to receive this study funded by the National Peanut Board and published in the New England Journal of Medicine, January 2008.
Roles of enzymes in inactivating the anaphylactic reaction
According to the National Peanut Board's press release, the board, an industry group representing American peanut farmers, "has allocated nearly $5 million in food allergy education and research efforts including the groundbreaking work being done by Dr. Gideon Lack in the UK, Dr. Peter Vadas from Canada, and Dr. Wesley Burks out of Duke University."
"Dr. Vadas's study, ‘Platelet Activating Factor, PAF- Acetylhydrolase and Severe Anaphylaxis...is the first to suggest that an enzyme found in the blood seems to decrease the severity of allergic reactions...The study shows that people who have life- threatening allergies and who have low levels of PAF acetylhydrolase in their blood suffer more severe allergic reactions than people with high levels of PAF acetylhydrolase."
How the study was conducted
I had a look at the study, which was conducted in 41 patients with anaphylaxis and in 23 control patients. "Serum PAF activity was also measured in 9 patients with peanut allergy who had fatal anaphylaxis and compared with that in 26 nonallergic pediatric control patients, 49 nonallergic adult control patients, 63 children with mild peanut allergy, 24 patients with nonfatal anaphylaxis, 10 children who died of nonanaphylactic causes, 15 children with life-threatening asthma, and 19 children with non-life-threatening asthma. In the cases of fatal anaphylaxis, the samples were examined retrospectively."
An interesting side note, as I mentioned anaphylaxis studies are difficult to do, the researchers mentioned that "Patients with anaphylaxis often present to the emergency department minutes or even hours after their symptoms begin, and for the purposes of clinical investigation, it takes additional time to obtain informed consent, enroll patients in the study, and perform venipuncture. Consequently, our results probably represent a conservative underestimate of the peak PAF concentrations generated during acute allergic reactions."
Also the study looked at patients that had died as a result of anaphylaxis, looking at serum samples "...collected from three male and six female patients who had fatal anaphylactic reactions to peanuts.." These samples, which were collected by three different coroners at the time of the fatal episode, were stored at -20°C and assayed, in duplicate, for PAF acetylhydrolase activity."
What does this mean?:
The outcome of the study suggests further research to, "...selectively block the actions of PAF (Platelet-activating factor), both as rescue therapy in cases of acute anaphylaxis and potentially as long-term preventive treatment for those at highest risk for fatal anaphylaxis."
