Cannabinoids Inhibit the CXCL12-Induced Migration of T Lymphocytes.

Cannabinoids are both exogenous compounds produced by Cannabis sativa, known for their psychoactive properties, and a family of related endogenous ligands whose functions have been recently characterized. The reported effects of cannabinoids on the immune system include inhibition of T lymphocyte proliferation, altered production of cytokines by T helper cells and decreased antibody formation by B cells. Cannabinoid receptors have been detected in several immune cells, including monocytes, macrophages, basophils and B and T lymphocytes. CB2 (Cannabinoid Receptor 2) appears to be the predominant cannabinoid receptor in the immune system, while the CB1 receptor is found primarily in the brain. We observed high levels of CB2 expression in the Jurkat T lymphocyte cell line, while others have reported expression of the CB2 receptor in CD8⁺ T lymphocytes. Here, we studied the ability of synthetic and endogenous cannabinoids to modulate a key function of T lymphocytes: chemotactic migration in response to the chemokine CXCL12 (also known as stromal cell-derived factor-1). We observed a 40–50% inhibition of CXCL12-induced chemotaxis in Jurkat T cells with the endogenous cannabinoid anandamide (at 15 μM concentration) and with the synthetic cannabinoids CP55,940 and Win-55,212–2 (each at 10 μM concentration). Inhibition occurred in a dose-dependent manner, indicating that it is a regulated, receptor-mediated process. Further studies showed that the inhibition of migration involved, in part, significant down-regulation of the CXCL12 receptor, CXCR4. We are currently elucidating the signaling cascade whereby endogenous cannabinoids may limit T cell migration in response to CXCL12. Thus, cannabinoids may be novel mediators of immunosuppression when clinically desired.