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Adv Exp Med Biol. 2001;493:223-8.

Downregulation of cannabinoid receptor 2 (CB2) messenger RNA expression during in vitro stimulation of murine splenocytes with lipopolysaccharide.

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Department of Medical Microbiology & Immunology, University of South Florida, College of Medicine, Tampa 33612, USA.


Cannabinoid receptor 2 (CB2) has been identified as the most abundant cannabinoid receptor subtype in the immune system. Bacterial lipopolysaccharide (LPS) is a potent stimulant of B cells, inducing proliferation and differentiation into antibody secreting cells. It has been reported that CB2 receptor expression is upregulated during human, tonsillar B cell activation through CD40. It was of interest to investigate the expression of CB2 mRNA using another B cell activator, LPS. Using northern blot analysis, we measured CB2 mRNA levels in murine splenocytes and enriched B cells. Results indicated that the 4.0 kb CB2 transcript was 2 fold higher in abundance in murine B cells than in whole splenocyte preparations. This observation confirmed data from others and from our previous RT-PCR studies that the expression of CB2 mRNA is more abundant in B cells. Upon LPS stimulation, CB2 transcripts were decreased 46% and 42% at 4 hours and 24 hours, respectively, when compared to unstimulated populations. An examination by flow cytometry of the CD69, early activation marker, on splenocytes, showed that the majority of the B cells were activated at 24 hrs. Thus, these results suggested that LPS stimulation of murine B cells caused a decrease in CB2 mRNA expression in contrast to the increase observed following human B cell stimulation through CD40.

[Indexed for MEDLINE]

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