Original article
Mechanisms of allergic and immune diseases
Characterization of Cannabis sativa allergens

https://doi.org/10.1016/j.anai.2013.04.018Get rights and content

Abstract

Background

Allergic sensitization to Cannabis sativa is rarely reported, but the increasing consumption of marijuana has resulted in an increase in the number of individuals who become sensitized. To date, little is known about the causal allergens associated with C sativa.

Objective

To characterize marijuana allergens in different components of the C sativa plant using serum IgE from marijuana sensitized patients.

Methods

Serum samples from 23 patients with a positive skin prick test result to a crude C sativa extract were evaluated. IgE reactivity was variable between patients and C sativa extracts. IgE reactivity to C sativa proteins in Western blots was heterogeneous and ranged from 10 to 70 kDa. Putative allergens derived from 2-dimensional gels were identified.

Results

Prominent IgE reactive bands included a 23-kDa oxygen-evolving enhancer protein 2 and a 50-kDa protein identified to be the photosynthetic enzyme ribulose-1,5-bisphosphate carboxylase/oxygenase. Additional proteins were identified in the proteomic analysis, including those from adenosine triphosphate synthase, glyceraldehyde-3-phosphate dehydrogenase, phosphoglycerate kinase, and luminal binding protein (heat shock protein 70), suggesting these proteins are potential allergens. Deglycosylation studies helped refine protein allergen identification and demonstrated significant IgE antibodies against plant oligosaccharides that could help explain cross-reactivity.

Conclusion

Identification and characterization of allergens from C sativa may be helpful in further understanding allergic sensitization to this plant species.

Introduction

Cannabis sativa is an herbaceous angiosperm belonging to the family Cannabaceae. C sativa and its resinous derivative hashish have a variety of industrial and more recently medicinal applications. The plant is most well known for its use as a recreational drug because it contains the psychoactive compound, Δ-9-tetrahydrocannabinol. An increase in marijuana consumption has been observed among teenagers in the United States.1 As a result of the increasing social and medical use, reports of allergic sensitization to marijuana are increasing in the peer-reviewed literature.[2], [3], [4], [5], [6], [7], [8], [9], [10]

Cases have been reported where hypersensitivity and even anaphylactic responses have been associated with marijuana use, and clinical symptoms include sore throat, nasal congestion, rhinitis, pharyngitis, wheezing, dyspnea, angioedema, and lacrimation.[2], [3], [4], [11], [12] In long-term and high-dose users, more severe manifestations of bronchitis and asthma with reduced vital capacity have been reported.12

Allergic sensitization to C sativa has been reported in occupational settings as well.13 Hemp workers involved in processing hemp fibers at a textile mill had significantly higher prevalence of chronic respiratory symptoms attributed to byssinosis. Sensitization of laboratory workers that handle and test marijuana has also been reported.[14], [15], [16]

The allergens of C sativa and its various derivatives are poorly characterized. Although Δ-9-tetrahydrocannabinol has been suggested to be an allergen,11 more recent studies show type 1 hypersensitivity to high-molecular-weight proteins derived from C sativa.[4], [6], [9], [10], [17], [18] In a recent study in Spain, IgE-binding proteins were observed with molecular weights ranging from 10 to 69 kDa.4 Others have identified patients sensitized to 2 prominent IgE-binding bands located at 10 and 14 kDa,9 and a 9-kDa lipid transfer protein was identified to bind IgE from a patient sensitized to C sativa.17 However, the identity of most allergens from C sativa remains unknown, and no allergens are currently listed by the International Union of Immunological Societies allergen nomenclature subcommittee.

Previously, we described 17 individuals who tested skin prick test (SPT) positive to crude extracts of marijuana buds and flowers.3 In all patients, exposure was primarily through smoking and direct contact with the plant. However, one patient was additionally exposed through consumption of marijuana tea. In this study, we characterize patient IgE reactivity to root, leaf, flower, and bud extracts in an attempt to identify potential allergens for patients sensitized to C sativa.

Section snippets

Patient Population

Serum samples were obtained from 17 individuals with inhalation and contact symptoms who were SPT positive to a crude C sativa extract from buds and flowers (macerated in water for 15 minutes), as previously reported.3 The most common symptoms after exposure to marijuana included rhinitis and conjunctivitis, periorbital angioedema, wheezing, and contact urticaria. Most SPT-positive patients had primary exposure to C sativa through smoking or direct contact to the plant. One patient also

IgE Reactivity to Various Parts of C sativa Plant

The protein profiles of root, leaf, bud, and flower extracts of C sativa are demonstrated in Figure 1A. Protein profiles of C sativa leaves, buds, and to some extent flowers were similar with a prominent approximately 50-kDa band common to these extracts. The extracts from flowers demonstrated prominent protein bands at approximately 18 and approximately 35 kDa that were absent in the other extracts. In contrast, the protein profile of C sativa root extract was distinct but was lacking the

Discussion

C sativa is widely used for various medicinal and industrial purposes.22 Recently, an increase in the recreational use of C sativa has been reported.[1], [23] Studies have focused on the overall health effects of C sativa consumption with less attention to aspects such as respiratory morbidity or allergic sensitization.22 Allergic responses to C sativa are rarely reported; however, it is likely that the social and legal aspects surrounding the recreational use of marijuana may discourage

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    Disclosures: Authors have nothing to disclose.

    Disclaimer: The findings and the conclusions in this report are those of the authors and do not necessarily represent the views of the National Institute for Occupational Safety and Health.

    Funding Sources: This study was supported in part by interagency agreement 12-NS12-10 with the National Institute of Environmental Health Sciences and the Centers for Disease Control and Prevention and in part by National Institute on Drug Abuse, National Institute of Health, Department of Health and Human Services, contract N01DA-10-7773.

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