Cyclosporine A inhibits the expression of costimulatory molecules on in vitro-generated dendritic cells - Association with reduced nuclear translocation of nuclear factor kappa B

Background The maturation of dendritic cells(DC) is influenced by various f actors, in particular cytokine-mediated signaling events. These include mod ulation of the activation of nuclear factor kappa B (NF-kappa B), which con trols the transcription of genes encoding major histocompatibility complex (MHC) antigens, and costimulatory/accessory molecules for T-cell activation . Here, we investigated the influence of cyclosporine A (CsA) on the in vit ro maturation of DC, and on the nuclear translocation and DNA binding of NF -kappa B. Methods, DC progenitors were propagated from mouse bone marrow in granulocy te-macrophage colony-stimulating factor (GM-CSF) or in GM-CSF plus either t ransforming growth factor (TGF)-beta or interleukin (IL)-4, in the presence or absence of CsA (1 mu g/ml). After 5 days of culture, cell surface expre ssion of MHC class I/II, CD40, CD80, and CD86 was analyzed by flow cytometr y, and nuclear NF-kappa B proteins by electrophoretic mobility shift, antib ody supershift, and Western blot assays. The antigen-presenting function of DC was determined in one-way mixed leukocyte reactions, Results. Exposure of replicating DC progenitors propagated in GM-CSF or GM- CSF+TGF-beta to CsA reduced costimulatory molecule expression, without affe cting MHC antigen expression. Nuclear extracts from the CsA-treated DC reve aled a decrease in nuclear translocation of NF-kappa B (p50), Mixed leukocy te reaction data were consistent with the flow cytometry and gel shift assa y results, and showed reduced allostimulatory ability of the CsA-treated ce lls compared with untreated controls. Addition of IL-4 from the start of DC cultures conferred resistance to CsA-induced inhibition of NF-kappa B nucl ear translocation and DC maturation. Conclusions. CsA differentially inhibits the expression of key cell surface costimulatory molecules by in vitro-generated DC. This effect can be overc ome, at least in part, by IL-4 and augmented by TGF-beta. The inhibition is linked to a decrease in nuclear translocation/DNA binding of NF-kappa B, T hus, CsA can alter the antigen presenting function of DC for T-cell activat ion.