Marijuana is the most widely used recreational drug in the world. Cannabis belongs to the Cannabaceae family, but the species Cannabis sativa and Cannabis indica have been selectively selected to develop their properties. These are the most common botanical varieties, but there is considerable variation in their strains. This is mainly due to the fact that the plant has undergone selective hybridization and cross-breeding since the 1970s. As a result, there is a wide range of cannabis strains, chosen for their unique biochemical profile. However, there are proofs that cannabis can cause both type 1 and type 4 allergy. Allergy type 1 is a “classic” one, with immediate allergic reaction with symptoms within 15-20 minutes. Type 4 is so-called delayed, peaking in ~48 hours after exposure.
What do we know now?
Allergen recognition may vary by country and continent. However, due to the fact that marijuana is illegal in many countries, testing is difficult, leading to problems in diagnosis. For the first time, description of allergic reactions to cannabis occured about 50 years ago as symptoms of rhinitis, conjunctivitis, asthma or skin reactions. We can identify over 140 phytocannabinoids in cannabis. These are terpenophenolic compounds present in plants. There are, among others in hops, oregano or truffles. Their main function is protection against insects and ultraviolet radiation. Delta – 9 – Tetrahydrocannabinol (THC) is the best-known cannabinoid with psychoactive effects. However, it is cannabis proteins that can act as allergens and contribute to type I allergic reactions. Many cannabis allergens have been sequenced and WHO/IUIS Nomenclature Subcommittee (www.allergen.org) approved four of them. These are:
– Nonspecific lipid transfer protein
– Protein that enhances the secretion of oxygen
– Protein associated with pathogenesis
Current research on cannabis allergies
However, there are still researches on many other proteins or carbohydrates that can potentially affect allergic reactions in the human body. The importance of the various allergens mentioned may vary depending on geographic location, previous sensitization to food or pollen, and other factors. Non-specific lipid transfer proteins are a common food allergen in Europe and are resistant to heat and the digestive system, thus activating reactions to both raw and cooked plant foods. Therefore, this allergy is a feature of European patients. In 2007, research shown for the first time that a patient allergic to this peach-derived protein also reacted to Cannabis sativa. Due to cross-reactivity between nonspecific lipid transfer protein, sensitized patients may develop a reaction to a wide range of fruits, vegetables and grains, as well as to wine, beer, Hevea latex and tobacco.
Diagnosing any allergy can be problematic, and a cannabis allergy poses additional difficulties, not least because of legal issues. Currently, there are no commercial allergy tests to diagnose cannabis allergies in a clinical setting. The development of allergy research and public education is possible in countries allowing marijuana for medical and/or recreational use. In order to collect as much real data as possible, the CAIG (Cannabis Allergy Interest Group) is aiming to set up a registry. The intention is to lead to the development of international guidelines for the diagnosis and treatment of cannabis allergy.