title: Hyporesponsiveness to the immunosuppressant effects of delta-8-tetrahydrocannabinol.
abstract: Delta-9-tetrahydrocannabinol (delta 9-THC) and delta 8-THC have previously been shown to suppress humoral immunity in mice. The purpose of these investigations was to determine whether a hyporesponsiveness develops to the immunosuppressive effect of delta 8-THC. BALB/c mice were administered 60 mg/kg delta 8-THC i.p. 2 days after an i.p. immunizing dose of sheep erythrocytes (sRBC). Significant inhibition of direct hemolytic plaque-forming cells (PFC)/spleen was observed on days 3--6, with peak day of inhibition occurring on day 4. The effective inhibiting dose 50 (ED50) measured on peak day of response was 40 mg/kg for PFC/10(6) spleen cells and 38 mg/kg for PFC/spleen. When mice were pretreated daily for 5 days with different doses of delta 8-THC, similar ED50's were detected. Under this pretreatment regimen, 5 or 10 mg/kg produced no immunosuppression. Daily treatment with 5 or 10 mg/kg delta 8-THC for 5 days prior to sRBC and varying doses of delta 8-THC administered 2 days after sRBC resulted in significantly higher ED50's and increased values for the slopes of the dose response curves. These results suggest that a hyporesponsiveness develops to the immunosuppressive activity of delta 8-THC.
mesh_terms: D000818:Animals; D000907:Antibodies, Bacterial / Q000096:biosynthesis; D000917:Antibody Formation / Q000187:drug effects; D000921:Antibody-Producing Cells / Q000276:immunology; D003520:Cyclophosphamide / Q000494:pharmacology; D004306:Dose-Response Relationship, Immunologic; D013759:Dronabinol / Q000494:pharmacology* / Q000031:analogs & derivatives; D006462:Hemolytic Plaque Technique; D007166:Immunosuppressive Agents; D007700:Kinetics; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C
chemical_list: D000907:Antibodies, Bacterial; D007166:Immunosuppressive Agents; C035731:delta-8-tetrahydrocannabinol; D013759:Dronabinol; D003520:Cyclophosphamide