Fas ligation induces IL-1 –dependent maturation and IL-1 –independent survival of dendritic cells: different roles of ERK and NF- B signaling pathways

The mechanisms that underpin the intriguing capacity of Fas ligation on dendritic cells (DCs) to induce maturation and activation, rather than apoptosis, remain unclear. In the present study we confirm that Fas signaling induces both phenotypic and functional maturation of murine DCs, and we demonstrate that phenotypic maturation is associated with phosphorylation of extracellular signal-regulated kinase (ERK)1/2, activation of caspase-1, and secretion of interleukin(IL-1 ). Specific inhibition of ERK1/2 diminished Fas ligation–induced caspase-1 activation, IL-1 secretion, and ensuing up-regulation of developmental markers, whereas treatment with neutralizing anti–IL-1 antibody abrogated phenotypic and functional maturation, indicating that IL-1 mediates Fas ligation–induced DC maturation in an autocrine manner. NFB activation was responsible for maintaining DC viability after Fas ligation. Inhibiting NFB did not affect either IL-1 secretion or phenotypic maturation but rather sensitized DCs to Fas-mediated apoptosis. In conclusion, positive signals originating from Fas are transduced through at least 2 different intracellular pathways in DCs, promoting not only survival but also an increase in maturation that correlates with increased antigen-presentation capability. (Blood. 2003;102:4441-4447)