Several reports suggest Sesame allergy has increased significantly worldwide over the past two decades. In 2021, sesame became the ninth major food allergen. On January 1, 2023, the FDA has required companies to label sesame as a food allergen on all prepackaged foods that include it. It is therefore essential clinicians understand the existing diagnostic pathways to achieve better patient outcomes.
Oral food challenges (OFCs) are the most accurate allergy tests available today. Usually, they are only used after a thorough evaluation of the patient's history, physical examination, and other diagnostic tests: skin prick tests and blood testing with whole allergen.
OFCs allow clinicians and patients to observe within minutes how the allergic reaction appears. But scheduling an OFC can mean a longer wait, and they are time-intensive procedures, so patients may experience unnecessary stress and anxiety. In rare cases, OFCs can carry a risk for anaphylaxis.
Skin prick tests determine IgE-mediated sensitization. These tests are safer than OFCs. But there can be false positives in the test, where pollen or peanut-specific IgE sensitization can be misidentified as sesame sensitization. Additionally, they do not indicate the risk of a systemic reaction.
Blood testing with whole allergen determines sensitization by testing for specific IgE to whole sesame within a patient blood sample, but it can’t identify the specific protein that may be causing a reaction. However, like the SPT, it does not indicate the risk for a systemic reaction and carries a possibility of cross-reactivity.
Discovering the exact protein to which patients are allergic can lead to appropriate management. Sesame contains seven allergenic components. Ses i 1 is one of the major allergens of sesame. Ses i 1 has been identified as a clinically relevant marker of severe allergic reactions (anaphylaxis). In a study conducted in Italy among 10 patients with sesame allergy (severe generalized reactions), 100% of the patients showed positive immunoglobulin E (IgE) reactivity towards Ses i 1. Additionally, a study performed in Japan involving 90 sesame-sensitized children found significantly higher levels of sIgE to Ses i 1 in OFC-positive patients (n=18) as compared to OFC-negative patients (n=72). Similarly, another study conducted in Japan, 92 sesame-sensitized children were divided into symptomatic (positive oral sesame challenge or convincing history, n=36) and asymptomatic (negative oral sesame challenge or sesame tolerant, n=56) patients. The results demonstrated a statistically significant association of Ses i 1 sensitization with the presence of allergic symptoms (skin, respiratory, gastrointestinal and cardiovascular symptoms) in symptomatic children (33 out of 36) as compared to asymptomatic children (18 out of 56).
Ultimately, Ses i 1 was proposed to be the best indicator of primary sesame allergy and could facilitate the diagnosis of sesame allergy, help assess the risk for severe reactions, assess the need for OFCs and potential outcome it, and allows clinicians to develop better management plans. This test is also available, does not require any special techniques or precautions, and carries no risk of systemic reactions.
