delta1-tetrahydrocannabinol, cannabidiol and cannabinol effects on the immune response of mice

delta1-tetrahydrocannabinol (THC) elicited a dose-dependent (1, 5, 10 mg/kg) depression of the immune response, of immature mice, stimulated with sheep red blood cells. The impairment of humoral immunity was specific for THC but not for cannabidiol at 25 mg/kg or cannabinol at 25 mg/kg. The mice were given four daily doses (i.p.) of either drug or vehicle (Tween 80-propylene glycol in 1% saline) or a single injection (i.p.) of sheep red blood cells in addition to four daily doses (i.p.) of drug or vehicle. Suppression of the antigenic response by THC was reflected as a reduction of splenic weight, reduction in the number of splenic antibody-forming cells, lowered hemagglutination titer and reduction in the percentage of splenic white pulp of total spleen volume.