Improving diagnosis of peanut allergy

Currently, a double-blind, placebo-controlled food challenge is the gold standard for diagnosing peanut allergy, but it is time-consuming, costly, and risks a severe reaction. Because of this, many patients are diagnosed based on their history of a suspected reaction after exposure to peanut coupled with results from skin-prick or serum testing using whole peanut extract. Results are not as accurate at predicting true food allergy, and some patients may be falsely diagnosed. This has lead a group of researchers in the UK to work on developing a more accurate test.

Research participants were drawn from the Manchester Asthma and Allergy Study, an unselected population-based birth cohort whose 1,085 participants have been followed prospectively since birth. Skin and blood tests at the eight-year clinical review showed 110 children from the cohort were sensitised to peanut. By conducting food challenges on 79 of these sensitised children, the researchers determined that only 22% of the sensitised group actually had a true allergy to peanut. In further tests on those with true food allergy, this group was found to react to specific peanut allergens, especially the protein Ara h 2.

The researchers concluded that the majority of children who have a positive skin test or measurable serum IgE to peanut do not have a clinical allergy to peanut, and suggest that measurement of an allergic response to the major peanut protein Ara h 2 is more useful in predicting clinical allergy.

An article about this research reported on www.medpagetoday.com cites many comments from external experts who maintain there are several limitations to the work, however if developed further the new testing strategy does offer promise in terms of providing more accurate diagnosis of true peanut allergy.

Reference: Nicolaou et al. 2010 Journal of Allergy and Clinical Immunology. Vol 125 pp. 191-197.