Sources of peanut allergy revealed

peanut allergy

Researchers from DTU Nanotech have examined patients’ immune reactions towards peanuts and discovered that the individual patient has allergic reactions towards very specific parts of the allergen and furthermore that this immune pattern does not change over time. This discovery may have a large impact on the future design of allergy vaccines.

Food allergy has large consequences for the individual and society. Allergy is caused by an immune response to the food eaten and some food allergies are so severe that the reaction can be fatal. One way to cure allergy is by vaccination, however, the design of vaccines require deep knowledge about how the “allergen”, the protein in the food, reacts with the immune system. One way to achieve this knowledge is to chop up the allergen in small parts and examine to which parts of the allergen the immune system reacts. These immune reaction patterns can then be used to design vaccines rationally.

Using high density peptide arrays in collaboration with DTU Food, DTU Systems Biology, University of Vienna and University of Toronto, researchers from DTU Nanotech found that patients did not change their immune response pattern over time. Associate Professor Martin Dufva from DTU Nanotech says that “This is good news as a vaccine would then likely cure the allergy. What complicates future vaccine development is the fact that patients had quite unique response patterns and this suggests that many different vaccines need to be developed”.

Testing 170,000 peptides

Martin Dufva continues: “The research was possible because we were given access to cutting edge peptide array technology from our collaboration partner, the company Roche”. A peptide is just another name for a short protein and “arrays” are simply spots on a glass slide where each spot carries a specific peptide. When the patient’s blood is put on the array, antibodies in the blood bind to the peptides on the array if there is a match.

Peanut allergy - illustration
Zoom-in of spots with different short proteins. The two spots shown contain two different short proteins. Antibodies from the patient (red) bind to some short proteins (exemplified by the left spot) but not to others (exemplified by the right spot).

Martin Dufva explains that “we used arrays of 170,000 different peptides of which 22,490 were from peanuts, this means that we tested the patients’ blood for reaction with 22,490 different parts of peanut protein at the same time”.

The arrays are designed using a computer which then guides the photolithography guided synthesis on the glass slide.

The smallest part of the protein is called an amino acid and a protein is just a chain of amino acids. With so large an array of peptides, it was possible to investigate the importance of every single amino acid and thus to obtain a detailed pattern of which specific parts of peanut proteins the patient reacts to.

Position Ara h 1.
Reactivity of one of the tested patients. The samples are from 2006, 2008 and 2012. Lines shows where in the peanut protein Ara1 patient antibodies bind.  Note how similar the patterns are between time points. Other patients had other patterns (data not shown).

The discovery can have large impact on the design of vaccines and the peptide array technology can furthermore be used for other applications where it is important to map the binding of antibodies such as in autoimmune diseases.

 

Read more in the journal article