N-formyl-methionyl-leucyl-phenylalanine induces and modulates IL-1 and IL-6 in human PBMC.

N-formyl-methionyl-leucyl-phenylalanine (fMLP), a bacterial derivative, induces and modulates various cellular responses linked to inflammation. In this work we evaluated the impact of fMLP stimulation on three pro-inflammatory cytokines: IL-1 alpha, IL-1 beta and IL-6. We found that fMLP induces the secretion of IL-1 alpha, IL-1 beta and IL-6 in human peripheral blood mononuclear cells (PBMC). It also increased LPS-induced secretion of these three cytokines. Northern blot analysis demonstrated that fMLP induced IL-1 alpha, IL-1 beta and IL-6 gene expression by human PBMC. The fMLP-induced IL-1 alpha and IL-1 beta gene expression and IL-6 secretion were abolished by pertussis toxin pretreatment, which suggests that the fMLP induction of cytokine was also mediated via a Gi protein. The concentration range of fMLP used to obtain these effects, in a dose dependent fashion, was 20 microM to 1100 microM. The mechanism by which fMLP modulates cytokine secretion is still not characterized. fMLP seems to share similar biological activities with other chemotactic factors (C5a, MCP-1, PAF, IL-8) that are able to modulate cytokines, and whose receptors belong to the same superfamily as the fMLP receptor(s).