Sesame allergy in children: New insights into diagnosis and management.

Sesame is a potentially potent allergen that can trigger skin, gastrointestinal, and respiratory tract symptoms, and anaphylaxis. Only 20% to 30% of sesame-allergic children develop tolerance. The prevalence of sesame allergy depends on local diets and ranges from 0.1% to 0.9%. A high risk of accidental exposure to sesame has resulted in mandatory food labeling in many countries. More than half of patients with sesame allergy are also allergic to peanut/tree nuts. Serum-specific IgE testing with a quantitative Ses i 1 component can be performed safely and has higher clinical specificity and better positive predictive value for oral food challenge (OFC) than whole sesame extract or skin prick testing (SPT). Compared with SPT or OFC, in vitro Ses i 1 testing requires no special techniques and carries no risk of reactions. Diagnosis of suspected sesame allergy begins with a thorough history and physical examination. A positive sesame extract test (≥0.1 kUA /L) should prompt further testing. In patients with a high probability of reacting, results of component testing may facilitate a decision about performing an OFC. In a Japanese study of OFC and Ses i 1, there was a 5% probability of a positive OFC with Ses i 1 sIgE levels <0.13 kUA /L, and a 50% probability of a positive OFC with levels >32.0 kUA /L. Most patients could safely consume sesame if sIgE levels were <0.13 kUA /L. Ses i 1 testing can be used to guide appropriate management (avoidance, emergency medication, and oral immunotherapy).

Combinatorial advantage of Ses i 1-specific IgE and basophil activation for diagnosis of sesame food allergy.

BACKGROUND: The prevalence of sesame food allergy (SFA) is increasing worldwide with the potential of anaphylactic reactions upon exposure. Utility of specific component IgE testing as an alternative to the oral food challenge (OFC), the diagnostic standard, is being investigated. METHODS: Patients (n = 42) with suspected SFA completed an open OFC to sesame. Diagnostic testing included serum levels of Ses i 1-specific IgE, skin prick test with high-protein extract, and basophil reactivity (% induced CD63 expression) for each patient. The diagnostic utility of these tests was evaluated at a 95% sensitivity, with the outcome measure being the number of OFCs required. RESULTS: Twenty-seven patients (64%) were diagnosed with SFA. Ses i 1 IgE differed significantly between allergic and tolerant patients (p = .0001). ROC curve analysis for Ses i 1 IgE yielded an AUC of 0.88 ± 0.05. Levels of Ses i 1 IgE correlated to induced CD63+ expression on basophils (p = .0001). Ses i 1 IgE was not sufficiently robust as a single step for diagnosis. Used concurrently, BAT and Ses i 1 IgE yielded correct positive classifications for 25 of 27 sesame-allergic patients with two false positives (93% PPV). Both tests were negative in 5 non-allergic patients. Patients with divergent Ses i 1 IgE and BAT results required OFC (n = 10, 24% of patients). Alternatively, sequential use of BAT, ruling in SFA followed by Ses i 1 IgE diagnosing non-allergic patients, yielded a 89% PPV, with 19% requiring OFC. CONCLUSION: Ses i 1 IgE and BAT used together can decrease the need for OFC in most SFA patients. A prospective cohort trial is necessary to validate these results.

Measurement of specific IgE antibodies to Ses i 1 improves the diagnosis of sesame allergy.

BACKGROUND: The number of reported cases of allergic reactions to sesame seeds (Sesamum indicum) has increased significantly. The specific IgE tests and skin prick tests presently available for diagnosis of sesame allergy are all based on crude sesame extract and are limited by their low clinical specificity. Thus, oral food challenge (OFC) is still the gold standard in the diagnosis. OBJECTIVE: The aim was to identify the allergen components useful to diagnose sesame-allergic children with the goal to reduce the number of OFCs needed. METHODS: Ninety-two sesame-sensitized children were consecutively enrolled and diagnosed based on OFC or convincing history. Specific IgE to purified native 11S globulin (nSes i 11S), 7S globulin (nSes i 7S), 2S albumin (nSes i 2S), and two recombinant 2S albumins (rSes i 1 and rSes i 2) was measured by ELISA and/or ImmunoCAP (rSes i 1/streptavidin application). RESULTS: Based on area under curve (AUC) values from receiver operating characteristic (ROC) analysis, rSes i 1 was shown to have the best diagnostic performance of the allergen components in ELISA. The experimental rSes i 1 ImmunoCAP test had larger AUC (0.891; 95% CI, 0.826-0.955) compared to the commercially available sesame ImmunoCAP (0.697; 95% CI, 0.589-0.805). The clinical sensitivity and specificity for the rSes i 1 ImmunoCAP test at optimal cut-off (3.96 kUA /L) were 86.1% and 85.7%, respectively. CONCLUSION AND CLINICAL RELEVANCE: Sensitization to Ses i 1 is strongly associated with clinical sesame allergy. Measurement of specific IgE to rSes i 1 could reduce the numbers of OFCs needed.

Diagnosis of Sesame Allergy: Analysis of Current Practice and Exploration of Sesame Component Ses i 1.

BACKGROUND: Sesame is an allergen of increasing importance. OBJECTIVE: We sought to characterize the outcomes of oral food challenges (OFCs) to sesame and evaluate the diagnostic accuracy of skin prick testing (SPT), sesame, and Ses i 1-specific IgE (sIgE). METHODS: We reviewed sesame OFCs performed at the Mount Sinai pediatric allergy clinic between January 2010 and April 2018. We assessed the accuracy of diagnostic tests by calculating the area under the curve (AUC) of the receiver operating characteristic curves. The association between OFC outcome and sesame sensitization was analyzed using a logistic regression, which was then used to estimate the 95% positive predictive value (PPV) of these tests. RESULTS: We identified 341 patients (69% male, mean age 7.7 years) who underwent sesame OFC. Among 106 (31%) positive OFCs, the median cumulative eliciting dose was 500 mg sesame protein (1/2 teaspoon tahini). Sesame SPT wheal ≥6 mm had sensitivity 54.1% and specificity 87.8%; AUC 0.756 (95% confidence interval [CI], 0.699-0.814). SPT wheal size ≥14 mm had 95% PPV. Sesame-sIgE level did not correlate with OFC outcome. Ses i-sIgE levels were analyzed in 30 patients using the Immuno Solid-phase Allergen Chip (ISAC) microarray and were significantly associated with OFC outcome (AUC: 0.715 [95% CI, 0.541-0.890]). Ses i 1-sIgE ≥0.3 ISAC Standardized Units had sensitivity 58.3% and specificity 83.3%. CONCLUSIONS: This is the largest study of sesame allergy to date. Sesame SPT is a more accurate predictor of sesame allergy compared with sesame sIgE. Ses i 1-sIgE appears promising but requires further study regarding diagnostic accuracy.