Cannabis allergy: what the clinician needs to know in 2019.

INTRODUCTION: Although the use of cannabis dates back millennia, the first description of cannabis allergy is relatively recent (1971). Recent large-scale data show that cannabis allergy can manifest severe and generalized symptoms with extensive cross-reactions. Thus, it is essential to become familiarized with its clinical presentation, diagnostic aids, and adequate therapeutic guidance. Areas covered: Here we provide a hands-on overview on cannabis allergy focusing on symptomatology and the reliability of diagnostic options. Recent advances in proteomics are discussed in detail, elucidating the link with nsLTP-related allergies. The proteomics advancements have paved the way for more reliable diagnostics, especially component-based tools. Finally, the current experience in treatment options is highlighted. Expert opinion: Cannabis allergy is an allergy entity which can significantly impact the quality of life. For optimal diagnosis, we advise to start with a validated and standardized crude-extract based test such as sIgE hemp complemented by component-based diagnostics such as sIgE Can s 3 quantifications where available. Future research should lift the veil on the true prevalence of cannabis allergy and the importance of other cannabis allergens to further guide our practice.

Exploring the Diagnosis and Profile of Cannabis Allergy.

BACKGROUND: Cannabis allergy (CA) has mainly been attributed to Can s 3, the nonspecific lipid transfer protein (nsLTP) of Cannabis sativa. Nevertheless, standardized diagnostic tests are lacking and research on CA is scarce. OBJECTIVE: To explore the performance of 5 cannabis diagnostic tests and the phenotypic profile of CA. METHODS: A total of 120 patients with CA were included and stratified according to the nature of their cannabis-related symptoms; 62 healthy and 189 atopic controls were included. Specific IgE (sIgE) hemp, sIgE and basophil activation test (BAT) with a recombinant Can s 3 protein from Cannabis sativa (rCan s 3), BAT with a crude cannabis extract, and a skin prick test (SPT) with an nCan s 3-rich cannabis extract were performed. Clinical information was based on patient history and a standardized questionnaire. RESULTS: First, up to 72% of CA reporting likely-anaphylaxis (CA-A) are Can s 3 sensitized. Actually, the Can s 3-based diagnostic tests show the best combination of positive and negative predictive values, 80% and 60%, respectively. sIgE hemp displays 82% sensitivity but only 32% specificity. Secondly, Can s 3+CA reported significantly more cofactor-mediated reactions and displayed significantly more sensitizations to other nsLTPs than Can s 3-CA. Finally, the highest prevalence of systemic reactions to plant-derived foods was seen in CA-A, namely 72%. CONCLUSIONS: The most effective and practical tests to confirm CA are the SPT with an nCan s 3-rich extract and the sIgE rCan s 3. Can s 3 sensitization entails a risk of systemic reactions to plant-derived foods and cofactor-mediated reactions. However, as Can s 3 sensitization is not absolute, other cannabis allergens probably play a role.