CB1 and CB2 cannabinoid receptors differentially regulate the production of reactive oxygen species by macrophages

We investigated the mechanism by which cannabinoid receptors-1 (CB1) and -2 (CB2) modulate inflammatory activities of macrophages. Real-time polymerase chain reaction showed the predominant CB2 expression in freshly isolated human monocytes. PMA, a potent inducer of differentiation, upregulated CB1 and increased CB1:CB2 transcript ratio from 1:17.5 to 1:3 in 5 days of culture. Immunohistochemistry showed that CB1 protein was colocalized in CD68-...