Cannabis allergy is real: lipid transfer protein Can s 3 identified as the main culprit | Research

The takeaway

Up to 72% of patients reporting cannabis-related anaphylaxis tested positive for sensitization to Can s 3, a lipid transfer protein, which also increases risk of allergic reactions to plant-derived foods.

Cannabis users who have experienced allergic reactions, and anyone curious about whether cannabis allergies exist.

72% of cannabis anaphylaxis cases linked to the allergen Can s 3

What the researchers found

Can s 3-based diagnostic tests showed the best combination of predictive values (80% positive, 60% negative) for confirming cannabis allergy. Can s 3-positive patients had significantly more cofactor-mediated reactions and cross-reactive sensitizations to other plant lipid transfer proteins.

Why it matters

Cannabis allergy is an emerging concern as legalization increases exposure. Standardized diagnostic tests don't exist yet, and many clinicians are unaware the condition exists. This study identifies the most reliable testing approaches.

The numbers in context

120 cannabis allergy patients studied. 72% of those with likely anaphylaxis were Can s 3 sensitized. Can s 3-based tests: 80% positive predictive value, 60% negative predictive value. sIgE hemp: 82% sensitivity but only 32% specificity. 72% of anaphylaxis patients also had systemic reactions to plant-derived foods.

How the study worked

Clinical study of 120 patients with cannabis allergy, stratified by symptom severity, compared against 62 healthy and 189 atopic controls. Five diagnostic tests were evaluated: sIgE hemp, sIgE and basophil activation test with recombinant Can s 3, BAT with crude cannabis extract, and skin prick test with nCan s 3-rich extract.

What this study cannot tell us

Not all cannabis allergy patients are Can s 3 positive, suggesting other allergens play a role. The study lacked standardized cannabis allergen preparations. Cross-reactivity patterns may vary by population and geographic region.

How to read the evidence

Moderate: clinical study with appropriate controls testing multiple diagnostic methods, though not randomized.

When this study was published

Published in 2019.

The bigger picture

As cannabis becomes more mainstream, allergic reactions will likely increase. Identifying Can s 3 as the primary allergen and establishing reliable diagnostic methods is a necessary step toward clinical guidelines that don't yet exist.

Questions still open

What other cannabis allergens beyond Can s 3 cause reactions? Could cannabis processing methods affect allergenicity? Do different cannabis strains have varying allergy risk profiles?

Common questions

Can you really be allergic to cannabis?

Yes. This study confirmed cannabis allergy in 120 patients, with symptoms ranging from skin reactions to full anaphylaxis. The primary allergen identified is a lipid transfer protein called Can s 3.

If you're allergic to cannabis, are you also allergic to other plants?

72% of cannabis allergy patients with anaphylaxis also had allergic reactions to plant-derived foods. This is because Can s 3 belongs to a family of proteins found across many plants.

Read the original research

Exploring the Diagnosis and Profile of Cannabis Allergy.

The journal of allergy and clinical immunology. In practice, 7(3), 983-989.e5

View on PubMed ↗Publisher’s paper ↗

Citation

Decuyper, Ine Ilona; Van Gasse, Athina Ludovica; Faber, Margaretha A; Elst, Jessy; Mertens, Christel; Rihs, Hans-Peter; Hagendorens, Margo M; Sabato, Vito; Lapeere, Hilde; Bridts, Chris H; De Clerck, Luc S; Ebo, Didier Gaston. (2019). Exploring the Diagnosis and Profile of Cannabis Allergy.. The journal of allergy and clinical immunology. In practice, 7(3), 983-989.e5. https://doi.org/10.1016/j.jaip.2018.09.017