Interleukin 6 production by mononuclear phagocytes can be stimulated by leukotrienes.

Leukotriene B4 is a potent lipid mediator of inflammation, and some of its bioactivities may involve inflammatory cytokines. Human monocytes, cultured in the presence of graded concentrations of LTB4, were significantly stimulated in their production of IL6. Nanomolar concentrations of the mediator were optimal for stimulation of IL6 production, which was already significant at 6 hours. LTC4 showed a similar, albeit lower activity. In addition to stimulating IL6 protein production, LTB4 also augmented IL6 mRNA accumulation, which was maximal at 1 hour. Furthermore, LTB4-treated monocytes contained increased amounts of nuclear protein capable of binding to potential transcriptional promoter regions of the IL6 gene. These data suggest that leukotrienes may modulate the production of IL6 and indicate some underlying mechanisms which may be involved.