Integrative Multi-Omics Analysis Reveals Biomarkers of Severe Systemic Allergy to Honeybee Venom and Olive Pollen

Allergies are often thought of as a simple mistake of the immune system, a case of the body overreacting to something harmless like pollen or a bee sting. But the reality is far more complex. While some people experience only a runny nose or a small, itchy bump, others face life-threatening reactions where their throat closes and their blood pressure crashes. Scientists have long known that the severity of these reactions varies wildly from person to person, but they have struggled to explain why. Is it simply a matter of how much of the allergen the body has seen before? Or is there a deeper, hidden difference in how the immune system is wired in those who suffer the most severe symptoms? Understanding this distinction is crucial because the current tools doctors use to predict who is at risk are often blunt instruments, unable to foresee which patient might have a catastrophic reaction to a treatment or a sting.

A team of researchers in Spain set out to solve this puzzle by looking at two very different types of allergies: reactions to honeybee venom and reactions to olive pollen. Both are common in their region, yet they present differently. Bee stings can trigger sudden, acute anaphylaxis, while olive pollen causes chronic respiratory issues like asthma and hay fever. The researchers wanted to know if the biological reasons for severe reactions were the same in both cases, or if each type of allergy had its own unique "signature" of severity. To find out, they moved beyond the standard blood tests that measure antibodies and instead looked at the entire chemical and protein environment of the blood. They examined thousands of tiny molecules, including metabolites which are the byproducts of the body's chemical processes, and proteins that act as messengers between cells. By combining these different layers of data with tests that measured how active the immune cells were, they hoped to uncover the specific molecular patterns that separate a mild case from a severe one.

The study involved two groups of patients: those allergic to honeybee venom and those allergic to olive pollen. Within each group, the researchers split the participants into two categories based on their clinical history. The "mild" group included people who had tolerated immunotherapy treatments without major issues, while the "severe" group consisted of those who had suffered multiple systemic reactions during treatment. The researchers then took blood samples from everyone to perform a deep dive into their biology. They measured specific antibodies, tested how the body's basophils—a type of white blood cell that releases histamine—reacted to the allergens, and analyzed the serum for hundreds of different proteins and metabolites. The goal was to see if the severe patients shared a common biological profile that the mild patients did not.

The results revealed that the body's response to severe allergy is not a single, uniform state but rather a collection of distinct, allergen-specific patterns. For the patients with severe honeybee venom allergy, the researchers found that the severity was not linked to higher levels of the usual allergy antibodies. Instead, the key difference lay in how the immune cells reacted and in the levels of certain stress-related chemicals. Severe patients showed a much stronger activation of their basophils when exposed to specific components of the bee venom, particularly Api m 1, Api m 4, and Api m 10. Their blood also contained higher levels of urea, a waste product, and specific inflammatory proteins like TNF and CXCL12. This suggests that severe reactions to bee stings are driven by a hyper-reactive immune system that is primed to launch a massive, systemic attack, accompanied by signs of acute metabolic stress.

In contrast, the patients with severe olive pollen allergy displayed a completely different biological profile. Their severity was closely tied to sensitization to a specific, less common component of the pollen called Ole e 7, rather than the most common component, Ole e 1. These patients had higher levels of antibodies against Ole e 7 and showed increased basophil activation when exposed to Ole e 1 and Ole e 3. However, unlike the bee venom group, their blood showed a decrease in certain energy-related molecules like carnitine and a specific type of fat called LPC 17:1. They also had elevated levels of different inflammatory signals, such as CCL3 and EGF, which are involved in tissue repair and chronic inflammation. This indicates that severe pollen allergy is less about an acute, explosive reaction and more about a complex, chronic state of inflammation that alters the body's energy metabolism and tissue structure.

When the researchers combined all these different data points—antibodies, cell activity, proteins, and metabolites—into a single integrated model, the distinction between mild and severe cases became incredibly clear. The model could successfully separate the two groups, proving that severe allergy is defined by a coordinated set of changes across the entire body, not just a single factor. For the bee venom group, the model highlighted a pattern of immune hyper-reactivity and acute stress. For the olive pollen group, it highlighted a pattern of chronic inflammation and metabolic shifts. The study explicitly ruled out the idea that the severity of an allergy is simply a matter of having more antibodies; in fact, the antibody levels were often similar between mild and severe patients. Instead, the severity is determined by how the body's cells and chemical systems respond to those antibodies.

This work suggests that the old way of looking at allergies, focusing mainly on the presence of antibodies, is insufficient for predicting who will suffer the worst outcomes. The researchers found that the body's response is highly specific to the type of allergen involved. A severe reaction to a bee sting is biologically distinct from a severe reaction to pollen, even though both involve the immune system. By identifying these specific molecular signatures, the study offers a new way to think about risk. It suggests that in the future, doctors might be able to look at a patient's full molecular profile to determine if they are at high risk for a severe reaction, allowing for more personalized and safer treatment plans. The findings do not provide a cure, but they do provide a clearer map of the terrain, showing that the path to severe allergy is paved with different molecular footprints depending on the allergen.