Cannabinoids have a profound anti-inflammatory effect, mainly through the CB2 receptor. Cell mediated immunity was found to be impaired in chronic marijuana users . A potent anti-inflammatory effect of cannabis was observed in rodents. Studying the functional roles of the endocannabinoid system in immune modulation reveals that it is involved in almost all major immune events. Cannabinoids shift the balance of pro-inflammatory cytokines and anti-inflammatory cytokines towards the T-helper cell type 2 profiles (Th2 phenotype) and suppress cell-mediated immunity, whereas humoral immunity may be enhanced. Cannabidiol was shown to reduce inflammation in a mouse model of rheumatoid arthritis and type I diabetes mellitus.