While many people can indulge in their favourite foods without concerns, others risk developing food anaphylaxis – a life-threatening allergic reaction. Knowing how you might react to food allergens can save your life. The difference between treating hives with Benadryl and carrying an EpiPen is literally life and death. Right now, most parents of children with allergies, and people who have suddenly developed a reaction to certain foods must adopt a ‘wait and see’ approach to how seriously to surveil their plate.
A New Blood Test
A new study, published in The Journal of Allergy & Clinical Immunology, is set to change that. The researchers at Ann and Robert H. Lurie Children’s Hospital show that individuals with elevated levels of an enzyme called α-tryptase, encoded by the TPSAB1 gene, are more likely to experience dangerous allergic reactions to food1.
Lab-based researchers found that a simple PCR test on blood or saliva specimens can determine your level of α-tryptase. The investigators hope it could translate into a diagnostic test to identify individuals at high risk of developing severe food allergies. To date, no such test exists, leaving people unaware of their risk of anaphylaxis.
Dr. Abigail Lang, the first author of the paper told Healio, ‘As clinicians, we are often asked by patients and families if a food allergy is mild or severe. Worries about reaction severity often significantly impact quality of life for patients with food allergies.’2
Here Comes the Science Part
Specialized immune cells called ‘mast cells’ produce tryptase enzymes in two forms: α-tryptase, encoded by the TPSAB1 gene, and β-tryptase, encoded by the TPSB2 gene3. The job of mast cells is to fight off invading pathogens. Sometimes, however, mast cells mistake food particles for pathogens and attack them. This can result in a life-threatening allergic reaction known as anaphylaxis. During anaphylaxis, mast cells activate and release both α-tryptase and β-tryptase into the circulation. Depending on an individual’s genetics, they might produce different levels of α-tryptase and β-tryptase3.
TPSAB1 – the Bug Bite Booster
Researchers have previously noted that an increase in TPSAB1 copy number correlates with more severe allergic reactions to insect stings (Hymenoptera venom allergy)4. In this study, the researchers aimed to test whether the same holds true regarding food allergies. To find out, they genotyped 119 individuals diagnosed with food allergies to determine how many copies of the α-tryptase gene they have. The results showed that people with more α-tryptase copies tended to have more frequent and more severe allergic reactions than those without any α-tryptase.
‘The presence of α-tryptase in subjects is correlated with a higher prevalence of anaphylaxis or severe reaction to food than in subjects without any α-tryptase,’ said Dr. Lang.
References
1Lang, A., Kubala, S., Grieco, M. C., Mateja, A., Pongracic, J., Liu, Y., Frischmeyer-Guerrerio, P. A., Kumar, R., & Lyons, J. J. (2023). Severe food allergy reactions are associated with α-tryptase. The Journal of allergy and clinical immunology, 152(4), 933–939. https://doi.org/10.1016/j.jaci.2023.07.014.
2Richard Gawel. (2023, August 18). Alpha-tryptase may indicate potential for severe food allergy reactions. Healio. https://www.healio.com/news/allergy-asthma/20230818/alphatryptase-may-indicate-potential-for-severe-food-allergy-reactions.
3 Sprinzl, B., Greiner, G., Uyanik, G., Arock, M., Haferlach, T., Sperr, W. R., Valent, P., & Hoermann, G. (2021). Genetic Regulation of Tryptase Production and Clinical Impact: Hereditary Alpha Tryptasemia, Mastocytosis and Beyond. International journal of molecular sciences, 22(5), 2458. https://doi.org/10.3390/ijms22052458.
4Ruëff, F., Przybilla, B., Biló, M. B., Müller, U., Scheipl, F., Aberer, W., Birnbaum, J., Bodzenta-Lukaszyk, A., Bonifazi, F., Bucher, C., Campi, P., Darsow, U., Egger, C., Haeberli, G., Hawranek, T., Körner, M., Kucharewicz, I., Küchenhoff, H., Lang, R., Quercia, O., … Wüthrich, B. (2009). Predictors of severe systemic anaphylactic reactions in patients with Hymenoptera venom allergy: importance of baseline serum tryptase-a study of the European Academy of Allergology and Clinical Immunology Interest Group on Insect Venom Hypersensitivity. The Journal of allergy and clinical immunology, 124(5), 1047–1054. https://doi.org/10.1016/j.jaci.2009.08.027.
