ABSTRACT
Marijuana and its major psychoactive component, ∆9-tetrahydrocannabinol (THC), have been shown to alter resistance to bacterial, protozoan, and viral infections in experimental animals and in vitro systems. These alterations have occurred correlative to modifications in the functional activities of a diverse array of cellular and humoral factors of the immune system. In addition, marijuana and THC, as well as other cannabinoids, have been reported to directly target the functional activities of lymphocytes, macrophages, natural killer cells, and other immunocytes from rodents and humans. It has been proposed that these activities are operative through both receptor and non-receptor mediated modes. Reports that marijuana and THC alter anti-microbial activity in vivo and in vitro, indicate that marijuana use presents a potential risk of decreased resistance to infections in humans. However, few controlled longitudinal epidemiological and immunological studies have been undertaken to correlate the immunosuppressive effects of marijuana smoke or cannabinoids on the incidence of infections or disease in humans.
