DELTA-9-TETRAHYDROCANNABINOL INHIBITS CELL CONTACT-DEPENDENT CYTOTOXICITY OF BACILLUS CALMETTE-GUERIN-ACTIVATED MACROPHAGES

The effect of delta-9-tetrahydrocannabinol (delta-9-THC), the major ps ychoactive component of marijuana, on the capacity of Bacillus Calmett e-Guerin (BCG)-activated macrophages to lyse L929 tumor cells, Naegler ia fowleri amoebae, and herpes simplex virus-infected cells was examin ed. Delta-9-THC inhibited tumoricidal and amoebicidal activity in a do se-related manner. Antiviral activity was decreased when mice received 25 and 50 mg/kg delta-9-THC. The cannabinoid did not directly suppres s the activation of macrophages as determined by levels of 5'-nucleoti dase activity and did not inhibit splenic T-lymphocytes of BCG-recipie nt mice from producing interferon gamma. Nomarski optics microscopy, s canning electron microscopy, and radiolabeling binding studies demonst rated that macrophages from delta-9-THC-treated mice retained their ca pacity to attach to their targets. These results suggest that delta-9- THC suppresses cell contact-dependent amoebicidal, tumoricidal, and an tiviral activities of activated macrophages at a stage following effec tor cell - target cell conjugation.