Delta-9-tetrahydrocannabinol inhibits the splenocyte proliferative response to herpes simplex virus type 2

The present investigation was undertaken to determine the effect of in vivo Delta-9-tetrahydrocannabinol (Delta-9-THC) treatment on immune responsiveness to secondary exposure to herpes simplex virus type 2 (HSV2) antigens in vitro. A splenocyte proliferative assay, employing HSV2-infected mouse embryo fibroblasts as target cells, was used to measure immune responsiveness. Administration of 50 mg/kg or 100 mg/kg Delta-9-THC to B6C3F1 mice in concert with HSV2 infection resulted in suppression of the proliferative response to HSV2 cell-surface antigens expressed on virus-infected mouse embryo fibroblasts. Similarly, in vitro treatment of HSV2-infected cells with Delta-9-THC (10(-7) M to 10(-5) M) resulted in a dose-dependent suppression of proliferative responsiveness of splenocytes of non-drug-treated HSV2-sensitized mice. These results suggest that Delta-9-THC inhibits immune responsiveness of B6C3F1 mice to homotypic challenge with HSV2. This inhibition may be resultant of drug action on both effector immunocytes and target HSV2 antigen-bearing cells.