December 20, 2011 — "Caution: This product may contain nuts." It's an increasingly common warning on food labels of all kinds, given recent heightened awareness of the dangers of nut allergies. Roughly 3 million Americans suffer from peanut allergies, yet current diagnostic methods don't detect every case.
New findings by scientists at the University of Virginia Health System, however, may allow for the development of more sensitive diagnostic tools and a better understanding of nut allergies.
Their study, "Structural and Immunologic Characterization of Ara h 1, a Major Peanut Allergen," appeared in the Nov. 11 issue of the Journal of Biological Chemistry.
The researchers determined that the emerging cutting-edge use of a recombinant, or artificially produced, protein in diagnostic tests may not be a suitable replacement for the natural protein Ara h 1, one of the major peanut allergens. This new insight will be critical in the effort to accurately diagnose peanut allergies and better understand their mechanisms.
"In allergy diagnostics, using a recombinant protein is thought to reveal more consistent results, as they are more homogenous than natural proteins. Individual protein molecules purified from a natural source show much more variation at a molecular level from one another," said study co-leader Wladek Minor, professor of molecular physiology and biological physics in the School of Medicine.
"However, people are exposed to allergens from natural sources, not recombinant protein," he continues, "and people develop antibodies to different fragments of natural allergens. If there is a significant difference between a natural source and the recombinant allergen used for allergy diagnosis, the recombinant allergen is not a good replacement in the test, because different types of allergies can be overlooked."
In their analysis, researchers also found strong similarities in the structure of the Ara h 1 protein and those of other plant-seed proteins, which could help explain why patients with peanut allergies frequently also have allergies to tree nuts such as walnuts, almonds and cashews.
For children and adults who suffer from these serious allergies, accurate and early detection is critical. Allergic reactions to peanuts and tree nuts are the No. 1 cause of food-induced anaphylaxis, a life-threatening condition that develops rapidly after consumption. Armed with an accurate diagnosis, however, allergy sufferers can learn to avoid certain foods and equip themselves with a portable injection of epinephrine, the lifesaving treatment for anaphylaxis.
The team's next steps in their research will be to determine exactly why peanut-allergic patients are often allergic to tree nuts as well, and to explain why peanut and tree-nut allergies are extremely difficult to outgrow, usually lasting a lifetime.
In addition to Minor, the international research team included Maksymilian Chruszcz, a member of Minor's U.Va. research group; Soheila Maleki, from the U.S. Department of Agriculture; and Heimo Breiteneder, from the Medical University of Vienna. The multidisciplinary study included structural, bioinformatics and immunological research on Ara h 1. Some methodology used in the project was developed as part of the National Institutes of Health's Protein Structure Initiative, and in particular the New York Structural Genomics Consortium.