Marijuana is one of the most abused drugs due to its psychotropic effects. Interestingly, it is also used for medicinal purposes. The main psychotropic component in marijuana, Δ 9 - tetrahydrocannabinol (THC), has also been shown to mediate potent anti-inflammatory properties. Whether the immunomodulatory activity of THC is mediated by epigenetic regulation has not been investigated previously. In this study, we employed ChIP-Seq technology to examine the in vivo effect of THC on global histone methylation in lymph node cells of mice immunized with a superantigen, staphylococcal enterotoxin B (SEB). We compared genome-wide histone H3K4, H3K27, H3K9, H3K36 trimethylation and H3K9 acetylation patterns in...