Atherosclerosis is a chronic inflammatory disease that is the primary cause of heart disease and stroke in Western countries. Derivatives of cannabinoids such as delta-9-tetrahydrocannabinol (THC) modulate immune functions and therefore have potential in the treatment of inflammatory diseases. German researchers investigated the effects of THC in a murine model of established atherosclerosis. Oral administration of THC (1 mg/kg per day) resulted in significant inhibition of disease progression. This effective dose is lower than the dose usually associated with the psychotropic effects of THC. Furthermore, the CB2 receptor (the main cannabinoid receptor expressed in immune cells) was detected in both human and mouse atherosclerotic plaques. Lymphoid cells isolated from THC-treated mice showed diminished proliferation capacity and decreased interferon-γ secretion. Macrophage chemotaxis, which is a crucial step for the development of atherosclerosis, was also inhibited in vitro by THC. All these effects were completely blocked by a specific CB2 receptor antagonist.