title: Effects of delta-9-tetrahydrocannabinol on human immune function and host defense.
abstract: This review examines evidence that delta(9)-tetrahydrocannabinol (THC) can regulate and suppress human immune responses. Leukocytes express both cannabinoid receptor type 1 (CB1) and cannabinoid receptor type 2 (CB2), and levels of mRNA encoding for them are increased in peripheral blood leukocytes obtained from marijuana smokers, suggesting cannabinoid receptor activation in vivo. Exposure of human T-cells to THC suppresses their proliferation, inhibits the release of interferon-gamma, and skews the balance of T-helper cytokines towards a type 2 response. The majority of these effects are CB2 receptor-dependent. Consistent with an impact of THC on cell-mediated immunity, alveolar macrophages (AMs) recovered from the lungs of marijuana smokers are suppressed in their ability to release pro-inflammatory cytokines and nitric oxide (NO), and kill bacteria. Macrophage function is restored by treatment with interferon-gamma, a type 1 cytokine. Habitual exposure to THC appears capable of impacting on human cell-mediated immunity and host defense.
authors.affiliation: Division of Pulmonary and Critical Care Medicine and Hematology/Oncology, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA. mroth@mednet.ucla.edu
authors.forename: Michael D
authors.initials: MD
authors.lastname: Roth
authors.forename: Gayle C
authors.initials: GC
authors.lastname: Baldwin
authors.forename: Donald P
authors.initials: DP
authors.lastname: Tashkin
mesh_terms: D002455:Cell Division / Q000187:drug effects / Q000276:immunology; D016207:Cytokines / Q000276:immunology / Q000378:metabolism; D013759:Dronabinol / Q000009:adverse effects / Q000494:pharmacology*; D006801:Humans; D007111:Immunity, Cellular / Q000187:drug effects*; D007166:Immunosuppressive Agents / Q000009:adverse effects / Q000494:pharmacology*; D007371:Interferon-gamma / Q000276:immunology / Q000378:metabolism; D007962:Leukocytes / Q000276:immunology / Q000378:metabolism; D008264:Macrophages / Q000187:drug effects / Q000276:immunology / Q000378:metabolism; D009569:Nitric Oxide / Q000037:antagonists & inhibitors / Q000096:biosynthesis; D043882:Receptors, Cannabinoid; D011955:Receptors, Drug / Q000187:drug effects / Q000276:immunology / Q000378:metabolism; D013601:T-Lymphocytes / Q000187:drug effects / Q000276:immunology
chemical_list: D016207:Cytokines; D007166:Immunosuppressive Agents; D043882:Receptors, Cannabinoid; D011955:Receptors, Drug; D009569:Nitric Oxide; D013759:Dronabinol; D007371:Interferon-gamma