Type I interferons in combination with bacterial stimuli induce apoptosis of monocyte-derived dendritic cells

Both type I interferons (IFNs) as well as lipopolysaccharide (LIPS) individ ually compromise selected monocytic or dendritic cell (DC) functions. This study investigates the influence of these agents on the differentiation and the regulation of cell death of monocyte-derived DCs generated in the pres ence of granulocyte-macrophage colony-stimulating factor plus interleukin-4 (IL-4). It is reported that excessive apoptosis occurred rapidly in monocy te-derived DC cultures, if IFN-alpha or IFN-beta was added in combination w ith LIPS or lipoteichoic acid (LTA). The small fraction of cells surviving in such cultures displayed a mature DC phenotype with expression of CD83, C D80, and CD86. IL-10 was found in the supernatants of monocyte-derived DC c ultures, if supplemented with LIPS or IFN-alpha plus LIPS but not in contro l cultures. When monocytederived DCs were generated in the presence of IFN- alpha without LIPS, these cells displayed an immature DC phenotype with a r eduction of cell recovery but no overt apoptosis. However, the addition of LIPS, LTA, LIPS plus IFN-gamma, or tumor necrosis factor alpha (TNF-alpha) plus prostaglandin E2 to such cells again resulted In the rapid induction o f apoptosis in the majority of cells, together with a reduced production of IL-12 p70 and TNF-alpha. Together, these data indicate an exquisite sensit ivity of monocyte-derived DCs to activation-induced cell death If generated In the presence of IFN-alpha, indicating the existence of an Important mec hanism of Immunosuppression caused by IFN-alpha -inducing agents, such as v iral or bacterial stimuli. (C) 2001 by The American Society of Hematology.