The diagnostic value of component-resolved diagnostics in peanut allergy in children attending a Regional Paediatric Allergology Clinic

Abstract

BackgroundTo date, diagnosing food allergies in children still presents a diagnostic dilemma, leading to uncertainty concerning the definite diagnosis of peanut allergy, as well as to the need for strict diets and the potential need for adrenalin auto-injectors. This uncertainty in particular is thought to contribute to a lower quality of life. In the diagnostic process double-blind food challenges are considered the gold standard, but they are time-consuming as well as potentially hazardous. Other diagnostic tests have been extensively studied and among these component-resolved diagnostics appeared to present a promising alternative: Ara h2, a peanut storage protein in previous studies showed to have a significant predictive value.MethodsSixty-two out of 72 children, with suspected peanut allergy were analyzed using serum specific IgE and/or skin prick tests and specific IgE to several components of peanut (Ara h 1, 2, 3, 6, 8, 9). Subsequently, double-blind food challenges were performed. The correlation between the various diagnostic tests and the overall outcome of the double-blind food challenges were studied, in particular the severity of the reaction and the eliciting dose.ResultsThe double-blind provocation with peanut was positive in 33 children (53 %). There was no relationship between the eliciting dose and the severity of the reaction. A statistically significant relationship was found between the skin prick test, specific IgE directed to peanut, Ara h 1, Ara h 2 or Ara h 6, and the outcome of the food challenge test, in terms of positive or negative (P < .001). However, we did not find any relationship between sensitisation to peanut extract or the different allergen components and the severity of the reaction or the eliciting dose. There was no correlation between IgE directed to Ara h 3, Ara h 8, Ara h 9 and the clinical outcome of the food challenge.ConclusionsThis study shows that component-resolved diagnostics is not superior to specific IgE to peanut extract or to skin prick testing. At present, it cannot replace double-blind placebo-controlled food challenges for determination of the eliciting dose or the severity of the peanut allergy in our patient group.Electronic supplementary materialThe online version of this article (doi:10.1186/s12887-016-0609-7) contains supplementary material, which is available to authorized users.

Ratios of specific IgG4 over IgE antibodies do not improve prediction of peanut allergy nor of its severity compared to specific IgE alone

“…It has been reported earlier 15,26 and now confirmed in the present study that the ratio of peanut-specific, and in particular of Ara h 2specific IgG 4 over IgE antibody levels is higher in subjects that tolerate peanuts than in those that are allergic to peanuts. In several In line with some earlier publications 6,9,12,[15][16][17] but opposite to some others, 2,7,18,19 our study found clear support for an association between sensitization to Ara h 2 and symptom severity during challenge. Conflicting results in very similarly designed studies such as the study by Blumchen et al 18 and the present study may perhaps be explained by differences in stop-criteria during challenge.…”

“…Traditionally, serum IgE tests like ImmunoCAP measure IgE against whole peanut extract. 2,7,18,19 Not only IgE against peanut extract but also against Ara h 2 can be found in peanut-tolerant subjects. In multiple studies, IgE to Ara h 2 has been reported to perform better than extract in discriminating peanut allergic patients from tolerant sensitized subjects, both in children 2-8 and adults.…”

“…With the advent of component-resolved diagnosis (CRD), the potential of serum IgE testing to distinguish between tolerance and allergy, and beyond that, to better assess the risk of severe reactions, has significantly increased. In multiple studies, IgE to Ara h 2 has been reported to perform better than extract in discriminating peanut allergic patients from tolerant sensitized subjects, both in children [2][3][4][5][6][7][8] and adults. 9 More recently, IgE against Ara h 6 has been reported to perform similarly well as Ara h 2 as biomarker for peanut allergy.…”

“…14 An association of IgE against Ara h 2 with symptom severity has also been reported, both in children and adults 6,9,15,16 as well as it being a good discriminator between mild and severe symptoms, 12,17 but there are also conflicting reports. 2,7,18,19 Not only IgE against peanut extract but also against Ara h 2 can be found in peanut-tolerant subjects. What tips the balance towards tolerance or (severe life-threatening) allergy?…”

Eosinophilic esophagitis phenotypes: Ready for prime time?

“…The use of anti-IgE has been shown to lead to a reduction of hospitalization in both severe asthma and children with inner city asthma with fall exacerbations (6). For food allergy, the use of component testing has suggested which patients might be at risk for anaphylaxis to food (7). It is possible to envision the use of phenotypes as an aid in personalizing the selection of a therapeutic option and giving us guidance in predicting the natural history of a patient with EoE.…”