We studied the effect of acute (1 h) or chronic exposure (7 and 14 days) to Δ9-tetrahydrocannabinol (Δ9-THC) on immune parameters in male Swiss mice. One hour after a dose of 10 mg/kg s.c., the splenocyte proliferative response to ConA and NK activity were not inhibited, but there was a significant decrease in the production of IL-2. After 7 days of treatment, when mice were tolerant to Δ9-THC-induced analgesia, these functional parameters were strongly inhibited and there was a persistent reduction in IL-2 and IFNγ. With 14 days exposure to the drug, splenocyte proliferation was significantly reduced only with 5 μg/ml ConA, and NK activity was still significantly depressed (about 37%). IL-2 had returned to the control value, whereas IFNγ was still 40% down. Flow cytometry analysis of spleen cell composition indicated no changes after the acute and 7 day treatments, but at 14 days there was a 20% decrease in the number of T lymphocytes, mirrored by a 26% increase of B lymphocytes. In conclusion, in vivo exposure to psychoactive doses of Δ9-THC has profound effects on immune function. This implies some important questions in relation to the liberalization of marijuana and its therapeutic uses.
Immune function alterations in mice tolerant to Δ9- tetrahydrocannabinol: Functional and biochemical parameters
Rubino T.;Parolaro D.
1998-01-01
Abstract
We studied the effect of acute (1 h) or chronic exposure (7 and 14 days) to Δ9-tetrahydrocannabinol (Δ9-THC) on immune parameters in male Swiss mice. One hour after a dose of 10 mg/kg s.c., the splenocyte proliferative response to ConA and NK activity were not inhibited, but there was a significant decrease in the production of IL-2. After 7 days of treatment, when mice were tolerant to Δ9-THC-induced analgesia, these functional parameters were strongly inhibited and there was a persistent reduction in IL-2 and IFNγ. With 14 days exposure to the drug, splenocyte proliferation was significantly reduced only with 5 μg/ml ConA, and NK activity was still significantly depressed (about 37%). IL-2 had returned to the control value, whereas IFNγ was still 40% down. Flow cytometry analysis of spleen cell composition indicated no changes after the acute and 7 day treatments, but at 14 days there was a 20% decrease in the number of T lymphocytes, mirrored by a 26% increase of B lymphocytes. In conclusion, in vivo exposure to psychoactive doses of Δ9-THC has profound effects on immune function. This implies some important questions in relation to the liberalization of marijuana and its therapeutic uses.
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