How pathology could help crack the peanut problem

Pathology testing to diagnose food allergies and monitor the effectiveness of a potential new treatment could transform the experience of food allergy sufferers and dramatically reduce risk for patients.

Professor Mimi Tang of the Murdoch Children’s Research Institute (MCRI) said new research by David Martino and colleagues from the MCRI showing a DNA blood test can predict allergic reactions to food could potentially help patients and benefit future research too.

The paper Blood DNA methylation biomarkers predict clinical reactivity in food-sensitized infants was based on patients who underwent food challenges, skin prick tests and allergen-specific IgE tests (a blood test) and compared these results to those of a DNA test.

Both skin prick and allergen-specific IgE (sIgE) tests are currently used to detect allergies, but a positive test result does not always correlate to allergic symptoms meaning that many individuals with a positive skin prick or sIgE test to a food do not have clinical allergy to that food. In many cases, a food challenge (where the patient consumes the food under supervision) is required to confirm the presence or absence of clinical allergy.

Unfortunately, food challenges can result in an allergic reaction (indicating clinical allergy) which poses a risk and causes discomfort for the patient. Also, food challenges are costly and time consuming. Therefore, researchers wanted to determine if the DNA test could be a more accurate way of finding out if patients would have an allergic reaction to foods such as peanuts, reducing the need to perform a food challenge.

Patients’ blood samples were examined for specific DNA biomarkers – these results were then compared to how patients actually responded during an oral food challenge where they ate the food itself to determine if the DNA test accurately predicted clinical allergy.

The DNA test was found to perform better than sIgE and skin prick tests; and may therefore be used in future to help diagnose allergies. It could also mean that future research in the area of food allergies will have a tool which monitors the participants’ allergic status without requiring them to take on a food challenge.

Early this year, results of another study, conducted by Professor Tang, showed that a special, high strength probiotic (digestive ‘good’ bacteria) treatment administered together with a peanut allergen (allergic trigger) to children with peanut allergy was effective in stopping allergic reactions to peanuts in the majority of children who received the treatment.

Sixty two children were randomized to receive either the probiotic-peanut treatment or a placebo treatment for 18 months. At the end of the trial, 80% of the children in the active treatment group were found to be “sustained unresponsive” to peanuts, meaning they no longer had an allergic response, compared to only 4% in the placebo group.

Researchers will continue to follow up with study participants every 3 to 4 years to monitor the duration of the treatment’s effect.

At the end of the study, the children were required to undergo a peanut challenge to assess whether they were able to tolerate peanut. Aside from the obvious anxiety, discomfort and risk of the food challenge for study participants, Professor Tang says using food challenges also has disadvantages for researchers as they require skilled nurses and doctors to perform. The availability of an alternative test that can detect allergy or tolerance to a food and does not carry a risk of allergic reaction would be an advantage.

“Using food challenges for research like this is costly and labour intensive. Having a blood test which can show quite accurately if treatment is effective will reduce cost as well as risk.”

As food allergies appear to be on the rise, these findings are timely and means that the future is looking more positive for allergy sufferers.