Differential expression of cannabinoid CB 2 receptor mRNA in mouse immune cell subpopulations and following B cell stimulation

Abstract

Cannabinoid CB 2 receptor is reported to be expressed in varying amounts in different human immune subpopulations. To examine the expression pattern of CB 2 in the mouse, immune cell subpopulations were purified and studied by semiquantitative Reverse Transcription-Polymerase Chain Reaction (RT-PCR). CB 2 mRNA was most abundant in splenic B cells, followed by macrophages and T cells. Furthermore, CB 2 was expressed in thioglycollate-elicited peritoneal macrophages, but not in resident peritoneal macrophages. In addition to these studies on receptor expression at basal activity, CB 2 mRNA expression was also studied following immune cell activation. Bacterial lipopolysaccharide stimulation downregulated CB 2 mRNA expression in splenocyte cultures in a dose–response manner, while stimulation through cluster of differentiation 40 (CD40) using anti-CD40 antibody upregulated the response and costimulation with interleukin-4 attenuated the anti-CD40 response. These results demonstrate that CB 2 mRNA expression differs among mouse immune subpopulations similar to what is observed in human immune cells. Furthermore, the results suggest that the signaling pathways activated by lipopolysaccharide and anti-CD40 might have different effects on CB 2 mRNA expression.