Sesame allergy: Role of specific IgE and skin-prick testing in predicting food challenge results

Abstract

INTRODUCTIONSesame seed is an emerging food allergen in the U.S. pediatric population as it becomes more common in the American diet. A recent systematic review of seed allergies described a prevalence of < 1% for sesame allergy as defined by a positive food challenge.1 It has been reported that most patients have sesame allergy before the age of 2 and about 20% of children with clinical allergy eventually develop tolerance.2 Another study described 9 of 30 children (30%) developing tolerance at an average age of 2.8 years.3 Dalal et al. reported anaphylaxis as the presenting symptom in 30% of children with sesame allergy, all occurring in patients less than 1 year of age.4 This is of significant clinical concern in children who are too young to describe their symptoms.Clinical diagnostic tests such as food-specific IgE levels and skin prick test (SPT) results may aid in deciding who will tolerate a food challenge compared to those who are likely to react.5 Diagnostic decision points for food-specific IgE antibodies have been published for common food allergens such as egg, milk, peanut and fish.6 , 7 However, there is conflicting data regarding the diagnostic value of sesame-specific IgE and SPT and currently there are no established thresholds that predict clinical reactivity. Zavalkoff et al. were unable to establish a sesame-specific IgE threshold with a 95% positive predictive value.8 In a paper published by Maloney et al., a fitted predicted probability curve of clinical reactivity to sesame in relation to sesame-specific IgE did not show a 90% or 95% predicted probability of a reaction.9 Lastly, Ho et al. identified a sesame SPT wheal diameter ≥ 8 mm as being predictive of a positive food challenge with > 95% accuracy.10 Oral food challenge was used as the gold standard by which performance characteristics (sensitivity, specificity, positive and negative predictive values) of sesame-specific IgE measurements and SPT wheal size were calculated. Receiver operator characteristic curve (ROC) analysis was utilized to determine a threshold that would differentiate children with true sesame allergy from those who are tolerant. The relationship between sensitization status and outcome measure was analyzed using logistic regression. Fitted predicted probability curves were plotted using the results from logistic regression.Serum samples were analyzed for sesame-specific IgE using an ImmunoCAP fluorescence enzyme immunoassay (Phadia AB, Portage, MI). The detection limit of the assay was 0.35 kU/L. A positive ImmunoCAP test was defined as ≥ 0.35 kU/L.Skin prick tests were performed in a standard fashion using the Multi-Test II device from Alk-Abello (Round Rock, TX) and commercially prepared extract from Greer Laboratories (Lenoir, NC). Negative controls with saline and positive controls with histamine were performed concurrently. The mean of the longest diameter and orthogonal diameter were measured in millimeters at 15 minutes. A positive SPT was defined as a wheal diameter ≥ 3 mm larger than the negative control....

Hypersensitivities to sesame and other common edible seeds

“…Similar to SPT, studies on sesame-sIgE showed inconsistent findings (62,90,92). In one study, 50 kUa/l had an 86% positive predictive value (92).…”

“…Similar to SPT, studies on sesame-sIgE showed inconsistent findings (62,90,92). In one study, 50 kUa/l had an 86% positive predictive value (92). In a study of 92 patients with sesame hypersensitivity based on positive challenge test or convincing history, the authors reported that a serum level of 3.96 kUa/l to the sesame allergen rSes i 1 had 85.7% sensitivity and 86.1% specificity (96).…”

“…Its reported diagnostic predictive value was mostly on sesame and the findings were inconsistent (90)(91)(92). Some authors reported a ≥8 mm wheal diameter had a 95% positive predictive value for challenge (93,94).…”

Friday Asthma Crisis in the Daughter of Two Bakers

“…Unlike eggs and milk, SFAbelongs to the group of foods, such as fish and peanuts that have a low rate of tolerance development (1,3). SFA is mainly acquired by contact and ingestion, but there are a few cases reporting sensitisation by inhalation (4)(5).…”

“…The gold standard to confirm food allergy is a classical food challenge. In fact, in the case of sesame allergy, skin prick tests (SPT) and specific IgEs have not been established as good predictors oftrue allergy (1,3).…”