BACTERIA AND BACTERIAL-CELL WALL CONSTITUENTS INDUCE THE PRODUCTION OF REGULATORY CYTOKINES IN DENDRITIC CELL CLONES

The primary function of dendritic cells (DC) is the uptake, processing , and presentation of antigens to unprimed T cells, but the regulation of these functions is largely unknown. The study of the signals that maintain DC in a resting state or that drive their activation has been hampered by the difficulties in obtaining pure DC populations. The av ailability of immortalized DC clones from differ ent tissues (spleen a nd skin) allowed us to investigate the regulation of cytokine producti on in response to physiological signals in the absence of contaminatin g cells. The DC clones exhibited the phenotypical and functional featu res of DC precursors and could phagocytose, albeit at a low rate, whol e bacteria. Heat-inactivated bacteria and bacterial cell wall products were tested for cytokine induction. Lipopolysaccharide, lipoteichoic acid, and gram-negative bacteria were potent inducers of tumor necrosi s factor or and interleukin 6 release, whereas gram-positive bacteria were less efficient The results suggest that microbial infections can directly promote cytokine DC release of relevant inflammatory response s as well as in the autocrine activation of DC. (C) 1996 Wiley-Liss, I nc.