Here we show that CD40L (ligand for CD40) failed to induce the production of tumour necrosis factor alpha (TNF-alpha), interleukin (IL-)-1 beta, IL-10 and IL-12 in macrophages matured in vitro in the absence of growth factors or in the presence of macrophage colony-stimulating factor (M-CSF). In contrast, enzyme-linked immunoabsorbent assay (ELISA) testing and cytofluorimetric (FACS) analysis demonstrated significant production of TNF-alpha and IL-1 beta, but not of IL-10 and IL-12 in macrophages maturated in the presence of CD40L and re-stimulated with CD40L. The priming effect of CD40L on TNF-alpha and IL-1 beta production was related to induction of CD40 expression. Finally, CD40L priming did not modify the cytokine response of macrophages to lipopolysaccharide. In conclusion, our results suggest that CD40/CD40L interactions are important for the activation of macrophages as effector cells that mediate inflammation and tissue damage in T cell-mediated inflammatory processes.
Copyright 2001 Academic Press.