Predictive value of skin prick tests using recombinant allergens for diagnosis of peanut allergy.

BACKGROUND

Current diagnosis of peanut allergy relies on natural extracts that lack standardization. Recombinant DNA technology allows production of pure biochemically characterized proteins. Their usefulness for peanut allergy diagnosis is not established.

OBJECTIVE

This study aimed to evaluate the diagnostic value of the 3 major recombinant peanut allergens.

METHODS

Recombinant (r) Ara h 1, rAra h 2, and rAra h 3 were produced according to the recommendations of good manufacturing practice for recombinant allergens. Skin prick tests (SPTs) and IgE ELISA assays were performed in 30 patients with peanut allergy and 30 control subjects without food allergy: 15 nonatopic and 15 sensitized to birch pollen. Disease severity was graded by clinical scoring.

RESULTS

All patients with peanut allergy showed positive SPT results to rAra h 2; 40% reacted with rAra h 1 and 27% with rAra h 3. No control subjects reacted with any of the recombinant allergens. Monosensitization to rAra h 2 was observed in 53% of patients. Neither SPT size nor levels of specific IgE were correlated with the disease severity. However, patients with monosensitization to rAra h 2 had a significantly lower severity score than polysensitized subjects and a lower level of specific IgE against peanut extract and rAra h 2.

CONCLUSION

Skin prick tests to individual recombinant peanut allergens appear to be a safe and effective diagnostic tool. Cosensitization to rAra h 2 and rArah 1 and/or rAra h 3 is predictive of more severe reactions.

CLINICAL IMPLICATIONS: Recombinant peanut allergens can be used by SPTs for diagnosis and evaluation of allergy severity.