LAUSR

Objective: Chronic immune activation and elevated numbers of circulating activated monocytes (CD16+) are implicated in HIV-associated neuroinflammation. The objective was to compare the level of circulating CD16+ monocytes and IFN-&ggr;-inducible protein 10 (IP-10) between HIV-infected cannabis users (HIV+MJ+) and noncannabis users (HIV+MJ−) and determine whether in-vitro &Dgr;9-Tetrahydrocannabinol (THC), a constituent of cannabis, affected CD16 expression as well as IP-10 production by monocytes. Design: The levels of circulating CD16+ monocytes and IP-10 from HIV+MJ− and HIV+MJ+ donors were examined. In-vitro experimentation using THC was performed on primary leukocytes isolated from HIV−MJ−, HIV+MJ− and HIV+MJ+ donors to determine if THC has an impact on CD16+ monocyte and IP-10 levels. Methods: Flow cytometry was used to measure the number of blood CD16+ monocytes and plasma IP-10 from HIV+MJ− and HIV+MJ+ donors. Peripheral blood mononuclear cells were isolated from HIV−MJ− and HIV+ (MJ− and MJ+) donors for in-vitro THC and IFN&agr; treatment, and CD16+ monocytes and supernatant IP-10 were quantified. Results: HIV+MJ+ donors possessed a lower level of circulating CD16+ monocytes and plasma IP-10, compared with HIV+MJ− donors. Further, monocytes from HIV+MJ+ donors were unable to induce CD16 expression when treated with in-vitro IFN&agr;, whereas HIV−MJ− and HIV+MJ− donors displayed pronounced CD16 induction, suggesting anti-inflammatory effects by cannabis. Lastly, in-vitro THC treatment impaired CD16− monocyte transition to CD16+ and monocyte-derived IP-10. Conclusion: Components of cannabis, including THC, may decelerate peripheral monocyte processes that are implicated in HIV-associated neuroinflammation.