IgE-Mediated Hypersensitivity Reactions to Cannabis in Laboratory Personnel

Background: There have been sporadic reports of hypersensitivity
reactions to plants of the Cannabinaceae family (hemp and hops),
but it has remained unclear whether these reactions are immunologic
or nonimmunologic in nature. Objective: We examined the IgE-binding
and histamine-releasing properties of hashish and marijuana
extracts by CAP-FEIA and a basophil histamine release test.
Methods: Two workers at a forensic laboratory suffered from nasal
congestion, rbinitis, sneezing and asthmatic symptoms upon
occupational contact with hashish or marijuana, which they had
handled frequently for 25 and 16 years, respectively. Neither
patient had a history of atopic disease. Serum was analyzed for
specific IgE antibodies to hashish or marijuana extract by research
prototype ImmunoCAP, and histamine release from basophils upon
exposure to hashish or marijuana extracts was assessed. Results
were matched to those of 4 nonatopic and 10 atopic control subjects
with no known history of recreational or occupational exposure to
marijuana or hashish. Results: Patient 1 had specific IgE to both
hashish and marijuana (CAP class 2), and patient 2 to marijuana
only (CAP class 2). Controls proved negative for specific IgE
except for 2 atopic individuals with CAP class 1 to marijuana and 1
other atopic individual with CAP class 1 to hashish. Stimulation of
basophils with hashish or marijuana extracts elicited histamine
release from basophils of both patients and 4 atopic control
subjects. Conclusions: Our results suggest an IgE-related
pathomechanism for hypersensitivity reactions to marijuana or
hashish. Copyright (C) 2011 S. Karger AG, Basel