Allergen component testing can help physicians better understand sesame allergy

Key takeaways:

• Oral food challenges carry a risk for allergic reactions.
• Skin prick tests do not indicate risks for reaction.
• Ses i 1 specific IgE is a major protein associated with systemic reactions.

Sesame allergies have sharply increased in recent years. With one in every 200 people in the United States now reporting a sesame allergy, it is now the ninth most common food allergy in the nation.

Sesame allergy tends to be a lifelong allergy. Only about 30% of sesame-allergic patients outgrow their allergy, and the effects are serious. Allergic reactions to sesame can range from mild symptoms such as hives all the way to potentially fatal responses such as anaphylaxis.

As of Jan. 1, 2023, the FDA has required manufacturers to label sesame as a food allergen on all prepackaged foods that include it. Thanks to this regulation, consumers will have the knowledge they need to make safe food choices.

Niti Chokshi

However, transitioning to new labeling practices is tricky. Since products displayed before the regulation might not list sesame as an allergen, consumers may, at least for a little while, find it hard to discern which foods are safe.

Additionally, some companies have started adding sesame to their products deliberately to sidestep the complex process of certifying their products as sesame-free, meaning those with a sesame allergy now have even less choice.

So, what does all this mean for sesame allergy diagnosis and management? I expect a growing number of patients may seek guidance from their primary care clinicians to help determine if they can safely eat sesame-containing foods, as well as ask advice on how to manage their allergies effectively.

As some of the most indicative tests to determine a sesame allergy need to be performed by specialists, I also expect that more patients will be referred. This is likely to add strain on the system, meaning that patients may have to wait longer to see allergy specialists, causing additional stress and uncertainty.

A journey fraught with challenges

Given the recent FDA regulations, primary care clinicians may find themselves spending more time on sesame allergy diagnosis and patient guidance than ever before. It is therefore essential we understand the existing diagnostic pathways and their potential limitations to help us deliver better patient outcomes.

Oral food challenges are the most accurate allergy tests available today. Performed by allergists, OFCs are the gold-standard test to determine if a patient has a food allergy.

OFCs can help identify the threshold or level of risk associated with a sesame allergy and allow clinicians and patients to observe within minutes how the allergic reaction manifests. Typically, they only are used after a thorough evaluation of the patient's clinical history and the execution of other diagnostic tests.

But scheduling an OFC can mean a longer wait, particularly as they are time-intensive procedures. What’s more, OFCs have significant risk associated with them, as they can, on rare occasions, cause life-threatening anaphylaxis. While OFCs are conducted in controlled environments to protect the patient, they still pose a small risk.

Clinicians can use two other indicative tests in the context of the patient’s history to support an OFC recommendation: skin prick tests and whole allergen specific IgE blood tests.

SPTs determine IgE-mediated sensitization. While they are safer for the patient than OFCs, there can be false positives on testing. Additionally, they do not indicate the risk for a systemic reaction. There is also a risk for cross-reactivity, where pollen or peanut-specific IgE sensitization can be falsely detected as sesame sensitization.

Blood testing with whole allergen determines sensitization by testing for specific IgE to whole sesame within a patient blood sample. However, like the SPT, it does not indicate the risk for a systemic reaction and similarly carries a possibility of the result being affected by cross-reactivity.

So, where do these tests leave us?

First, they leave us with unclear findings. The risk for cross-reactivity and the lack of specificity often mean clinicians can struggle to interpret the results of blood testing with whole allergen and SPTs. Consequently, deciding whether to refer the patient for an OFC becomes a complex task.

Second, they leave us with slow results. As patients may face long wait times for answers, they may experience unnecessary stress and anxiety.

Sesame allergen components

We can improve diagnostic accuracy and reduce OFCs with testing with sesame allergen components, which helps to bridge the gap between blood testing with whole allergen and OFCs.

Testing with sesame allergen component evaluates the presence of Ses i 1 specific IgE, a major protein associated with systemic reactions and clinical sesame allergies. With this test, we can help assess the risk for systemic allergic reactions to sesame in patients and help rule out cross-reactivity, particularly with allergens such as pollens and peanuts.

And the test shows remarkable promise.

Compared with testing with whole allergen, Ses i 1 testing demonstrates higher clinical specificity and superior predictive values for positive outcomes in OFCs. Specialists and primary care clinicians can both order these tests.

Testing with allergen components helps clinicians better understand a patient’s allergy, empowering health care providers to devise more detailed and personalized management plans. You can therefore identify patients with primary sesame sensitization more easily, assess the need for (and potential outcome of) OFCs, and improve diagnostic accuracy.

For patients, this is a big win. They get a quicker and more accurate diagnosis, a better understanding of how to manage their condition, and clear guidance on whether they need to avoid certain foods.

However, testing with allergen components should not be used for screening purposes. All diagnostics should be interpreted in the context of the patient’s history to support a food allergy diagnosis.

We already have seen the promise of testing with allergen components in several published studies.

For instance, one study conducted in Japan involving 90 sesame-sensitized children found higher levels of specific IgE to Ses i 1 in OFC-positive patients compared with OFC-negative patients. Overall, the study showed that specialists needed to perform fewer OFCs, which may be riskier for some patients, as the component test better predicted who was more likely to be OFC-positive.

Another Japanese study reported Ses i 1 sensitization in 92% of a symptomatic group and 32% of a sensitized but asymptomatic group. Here, a specific IgE level to Ses i 1 of 3.96 kU_A/L gave an 86.1% sensitivity and 85.7% specificity rate.

The study showed that measuring Ses i 1 specific IgE in patients with a suspected sesame allergy may help reduce the number of OFCs needed to confirm clinical reactivity, protecting patients likely to have a systemic reaction during the test.

Happier and healthier patients

As sesame allergies are rising, and as we feel the effects of the FDA’s new labeling requirements, I believe the number of patients seeking sesame allergy guidance may keep growing. While OFCs are still the most informative test, they are not suitable for everyone, and we urgently require simple indicative tests to determine who needs to be referred or challenged.

Testing with allergen components, in the context of clinical history and testing with whole allergen, can significantly improve sesame allergy diagnosis accuracy. Not only does it mean that we will need to refer fewer patients for potentially risky OFCs, but it also allows clinicians to develop better management plans for the patient.

Ultimately, these tests may help us give patients a faster, more precise diagnosis, and as they have a better understanding of safe diet choices, they can enjoy an improved quality of life.

References:

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For more information:

Niti Chokshi, MD, is an allergist and immunologist at Complete Allergy & Asthma, Houston, as well as the co-owner of Complete Allergy and Asthma.