TNF-α stimulates the biosynthesis of complement C3 and factor B by human umbilical cord vein endothelial cells

The human umbilical cord vein (HUVEC) endothelial cells synthesize and secrete complement components. We analyzed the regulation of biosynthesis of the third component of complement (C3) and factor B (Bf) by cytokines in endothelial cells. Production of C3 increased after stimulation with TNF-α or IL-1β and that of Bf with TNF-α, TNF-β and IFN-γ. TNF-α was the most effective in stimulating the secretion of C3 and Bf or the expression of mRNA of C3 or Bf. Preincubation with TNF-α for at least 36 or 24 h was needed for the stimulation, respectively. TNF-α, together with IFN-γ had synergistic effects and the release of C3 or Bf increased to about 40- and 26-fold higher than those in control cells after incubation with both cytokines.