Cannabinoid receptor-independent suppression of the superoxide generation of human neutrophils (PMN) by CP55 940, but not by anandamide

Cannabinoids have been shown to affect various immune functions. To date, almost no data exist on PMN, which provide the first line antimicrobial defense. The objective of the present study was to investigate the effects of the synthetic dibenzopyrane ligand CP55 940, the endogenous cannabinoid anandamide and methanandamide on the "respiratory burst" of isolated human PMN in vitro. After preincubation with high micromolar concentrations of CP55 940, fMLP-stimulated PMN showed a reduction in superoxide production, whereas the spontaneous burst activity of resting PMN remained unaffected. This inhibitory effect of CP55 940 was not CB-receptor-mediated. In contrast, anandamide and methanandamide did not alter the oxidative microbicidal PMN function.