Cannabis is the most frequently consumed illicit drug in the world. Mammals express at least two types of cannabinoid receptors (CBRs), cannabinoid receptor 1 (CB1) and cannabinoid receptor 2 (CB2). Previous studies demonstrated that peptide pulsed bone marrow DCs (BMDCs) from CB1-/-CB2-/- mice induced a CD8+ T cell response in the absence lipopolysaccharide (LPS)-induced DC maturation. DCs are professional antigen presenting cells indispensible in linking the innate and adaptive immune response. Each distinct DC subset has its unique set of surface markers and capabilities to respond to environmental stimuli and process antigen. The objective of the present study is to characterize the role of CBRs on the development and function of DC subsets from mouse bone marrow (BM). Our results demonstrate CB1-/-CB2-/- mice have a higher percent of BMDCs in freshly isolated BM and after 24 hours in culture in comparison to WT. Freshly isolatedBM cells isolated from CB1-/-CB2-/- mice elicited a CD8+ T cell response in the absence of LPS stimulation. Interestingly, there were no differences in MHC I or antigen-bound MHC I complexes on the surface of DCs that can account for this exacerbated activity. CD83, a DC marker implicated in maturation and stimulation of T cells, had a lower expression in DCs from CB1-/-CB2-/- mice. Taken together the results from this investigation suggest that CBRs are involved in DC bone marrow development and maturation.
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