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

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.