Cannabinoid receptor expression in immune cells

Abstract

A novel highly-sensitive and semi-quantitative technique, mutagenic RT- PCR (MRT-PCR) was used to discriminate the expression of neural cannabinoid receptor (CB1) mRNA versus that of peripheral cannabinoid receptor (CB2) mRNA in immune and neural cells. Human pre-monocytic THP-1 cells were shown to exclusively express CB1 message. Conversely, human pre-monocytic HL-60 cells and U-937 (histocytic lymphoma) cells exclusively expressed CB2 message. Anti-CB1 affinity-purified antibody generated to an immunodominant epitope within the amine terminus of CB1 detected CB1 protein in rat brain in a pattern which paralleled that previously reported in autoradiographic studies which utilized whole brain sections and [3H]CP55,940, a high-affinity cannabinoid ligand. Minimal immunocytochemical staining was detected in rat spleen. Collectively, these results, taken in context of reports which indicate CB2 distribution in peripheral tissues, indicate that CB1 is compartmentalized to neural tissue while CB2 is localized in immune cells.