A more sensitive peanut allergy test

Chemists at the University of Connecticut (UConn) have developed a peanut allergy test which is said to be far more sensitive than current procedures. It is hoped that the blood test will be better able to diagnose the severity of an individual’s allergic reaction, which can range from hives to anaphylactic shock.

When an allergic person eats peanuts, their immune system releases the antibody protein immunoglobulin E (IgE). These antibodies fight off peanut allergen molecules by binding to them and flushing them out of the body. But the release of the antibodies causes tissue cells in the body to produce histamine, which in turn generates a variety of allergy symptoms. The more antibodies that are released, the more histamine is generated - and the stronger the allergic response.

Professor James Rusling and Associate Professor Mark Peczuh pictured with the object of their research. Image credit: Peter Morenus/UConn.

Existing peanut allergy tests can generally measure IgE antibodies found in a blood sample, but the presence of other biomolecules can distort the results. Co-author Associate Professor Mark Peczuh said the traditional method of measuring these antibodies “uses a mixture of all the peanut proteins … [which] can lead to readings that a patient is allergic when she or he is not” - or vice versa.

The new test screens out other biomolecules and measures the presence of antibodies that bind to very specific protein fragments, called peptides, and carbohydrate residues found in peanuts. The chemists tested both these components in their new system, then injected blood serum from patients known to have peanut allergies into the array.

As the blood serum floated over the samples, IgE antibodies were pulled down by the allergens and bound by them. This meant the team could measure the quantity of antibodies to determine how strong a reaction a person would have to peanuts. The researchers also attached magnetic beads to the allergen samples, which captured the IgEs and amplified the final measurements.

The results, published in the journal Analyst, correlated with the patients’ known allergy levels from other tests. And while the trial test was limited to just a few allergic components from peanut glycoproteins, co-author Professor James Rusling says it could be expanded to screen for more than 20, allowing for even more selective results.

“Eventually, we’d like to use maybe five different peptides and carbohydrate samples to see how these IgEs bind to them,” Professor Rusling said. “That way, we could determine a clear fingerprint of a patient’s susceptibility to a specific allergen.”

Professor Rusling added that the test may eventually be used as “an analytical tool to investigate the actual biology of the allergic response to peanuts and other food items in general”. As there has been some debate over the role carbohydrates play in allergies, and the new system can test both protein peptides and carbohydrate residues, the researchers hope they may learn more about how specific protein and carbohydrate epitopes bind to antibodies to gain a better understanding of how allergies are induced.

Source

Originally published here.