Rapid allergic reactions to substances like food or drugs are called anaphylaxis. When severe, anaphylactic reactions can even cause death. Life-threatening reactions like these produce signal molecules in the body, which doctors call biomarkers.
Scientists expect biomolecules for anaphylaxis should be present in individuals at risk of an anaphylactic reaction. If so, these signal molecules would help doctors diagnose an anaphylactic event when it happens. However, biomarkers for anaphylaxis are currently unknown.
The earliest symptoms of anaphylaxis are similar to symptoms of common allergic reactions, so doctors struggle to tell the difference between mild allergies and life-threatening anaphylactic events. Since researchers have not yet identified biomarkers for anaphylaxis, doctors cannot run specialized tests to show whether or not someone is at risk of having a severe reaction.
Scientists have previously used a method that identifies how body processes respond to a stimulus, called a metabolomic analysis, to study biomarkers. Researchers have successfully used metabolomic studies to identify biomarkers involved with less severe reactions, such as asthma and common allergies.
Scientists from Spain recently used metabolomics to study patients with anaphylaxis. They hypothesized anaphylactic events brought on by different substances and with different severity would influence how the body responds to these reactions.
The scientists studied 18 patients admitted to hospital emergency rooms with anaphylactic reactions. The researchers compared patients with different triggers, either food or drugs, at different levels of severity, either moderate or severe. They also tested the patients at different times after their reaction began, since anaphylactic events occur in three stages, the immediate reaction, the initial recovery, and the full recovery.
About half of the anaphylactic reactions they examined were drug-induced, more than 30% were food-induced, and about 20% occurred spontaneously. Scientists also categorized each reaction by severity: 8 of the reactions were severe, 9 were moderate, and 1 was mild. Finally, the team took blood samples at each stage of reaction for each patient. The team examined the differences in metabolomics during the individual anaphylactic events to see if they showed different metabolic changes.
The researchers analyzed the blood levels of molecules called metabolites created during each patient’s response. They found different metabolite levels in patients experiencing drug-induced versus food-induced anaphylaxis. They also found differences in how much metabolite levels changed during the different stages in moderate versus severe reactions. Once the patients were fully recovered, those who experienced severe reactions had higher levels of metabolites with known anti-allergy properties.
The team interpreted their data to mean how the body responds to an anaphylactic reaction differs according to what caused it. They also suggested the differences in metabolomics during moderate versus severe anaphylaxis could be used by doctors to understand possible risk factors for life-threatening events.
These researchers were able to identify unique biomarkers for anaphylactic reactions that depend on their causes and levels of severity, but questions remain. External factors like patient age and medications in their bloodstream were difficult to control in an emergency room setting.
The team suggested future metabolomic studies should be expanded into larger clinical trials, which would allow for a wider range of reactions to be examined under more carefully controlled conditions. More studies of anaphylaxis biomarkers will help doctors and medical professionals diagnose this disease and identify patients at risk of severe reactions.