Differential activation of NF-kappa B subunits in dendritic cells in response to Gram-negative bacteria and to lipopolysaccharide

Dendritic cell (DC) maturation is essential for the initiation of T-depende nt immune responses. Nuclear factor kappaB/Rel (NF kappaB/Rel) transcriptio n factors are ubiquitously expressed signalling molecules, known to regulat e the transcription of a large number of genes involved in immune responses , including cytokines such as IL-1, IL-6, TNF-alpha and cell surface molecu les (MHC class I and II, B7.2). In this study, we have compared the activat ion of five members of the NF-kappaB family, p65, c-Rel, p50, RelB and p52, during DC maturation in response to lipopolysaccharide (LPS) and to Salmon ella typhimurium. We have shown that although the translocation of NF-kappa B occurred very early, 30 min after treatment with both S. typhimurium and LPS, bacteria-induced NF-kappaB activation was more pronounced. Four out of five members, i.e. p65, c-Rel, p50 and RelB, were similarly activated upon the two stimuli but with different kinetics. Indeed, we have observed that p65, c-Rel and p50 were translocated early, whereas RelB was translocated later in DC activation. This differential regulation suggests that the vari ous members of NF-kappaB family can mediate distinct functions of DC physio logy. (C) 2001 Editions scientifiques et medicales Elsevier SAS.