Clinical Information

De novo IgE sensitization to Sesamum indicum (sesame) seed and related products, such as sesame seed oil, can occur in both children and adults. In the United States, 0.21% of children and 0.24% of adults have reported convincing sesame allergy, but this varies around world. While sesame allergy is the ninth most common childhood food allergy in the United States, it is the third most common food allergy in Israel, with a prevalence of 0.93% in children. The allergy commonly lasts for life, with only 20% to 30% of children gaining tolerance to sesame seed. The median age onset for sesame allergy is 1 year. The use of whole sesame seed and its derivatives in food and health products is growing worldwide.

Sesame seed contains many components capable of eliciting an allergic response. A prospective multicenter European investigation suggests that sesame seed can cause allergic reactions that are more severe compared to other common seeds and nuts. In one study (n=16), 56% of patients developed urticaria while 38% presented with anaphylaxis after exposure to sesame seed. However, rhinitis and asthma have also been reported. Ses i 1 is the major allergenic component of sesame. 2S albumins, like Ses i 1, are extremely stable proteins, able to withstand temperatures up to 100° C, acidic conditions, and pepsin digestion. Consequently, immunological exposure to these proteins is thought to occur directly in the gut, resulting in sensitization or an allergic response. Seven sesame seed components are registered by the joint World Health Organization/International Union of Immunological Societies Allergen Nomenclature Subcommittee including Ses i 1 and Ses i 2 (2S albumin proteins), Ses i 3 (7S vicilin-like globulin), Ses i 4 and Ses i 5 (oleosins), and Ses i 6 and Ses i 7 (11S globulins). Ses i 1 is the major allergenic component of sesame.

Of all sesame protein components, serum IgE antibodies against Ses i 1 are the most useful for diagnosis of sesame allergy. Measurement of IgE against Ses i 1 for the diagnosis of sesame allergy was shown to have a sensitivity and specificity of 86.1% and 85.7%, respectively, using a cutoff of 3.96 kUa/L. Comparatively, measure of IgE against sesame extract (cutoff of 7.97 kUa/L) had a similar sensitivity of 83.3%, but a much lower specificity of 48.2% due to known cross-reactivity with peanut and tree nuts/seeds. In the same study, it was shown that 92% of symptomatic patients were sensitized to Ses i 1, while only 32% of nonsymptomatic patients were sensitized.

Despite minor homology between 2S albumins, crossreactivity with other 2S albumin proteins still exists, such as those found in sesame seed, hazelnuts, peanuts, English walnuts, Brazil nuts, cashews, pistachios, poppyseed, or rapeseed. For example, Ses i 1 and Ses i 2 are related the peanut allergens Ara h 2, 6, and 7. Sesame seed allergy can coexist with peanut and tree nut allergies, and co-sensitization with these allergens, alongside kiwi and rye, have been reported. There is varying prevalence of sesame seed and tree nut/peanut related allergy coexistence. Sesame seed allergy coexists with 15% to 54% of self-reported peanut allergies, 8% to 14.8% of tree nut allergies, and 50% to 54% of patients who have both tree nut and peanut allergies.