Monocyte‐derived dendritic cells do not proliferate and are not susceptible to retroviral transduction

Abstract

Dendritic cells may be generated ex vivo from CD34+ progenitor cells or peripheral blood mononuclear cells. Initial reports suggested that monocyte-derived dendritic cells (MoDCs) arise from a proliferating precursor and several groups subsequently reported successful retroviral transduction of these cells, again implying that cell division occurs. As this is of importance in the development of immunotherapy protocols, we investigated whether monocytes proliferate as they differentiate into MoDCs and also their susceptibility to retroviral transduction. During MoDC differentiation, there was a 51 +/- 12% reduction in cell number, 98% of cells were in G0/G1, no DNA synthesis was detectable and the cell cycle regulatory proteins pRb and p130 were in the hypophosphorylated forms observed in non-cycling cells. As expected from these results, MoDCs were refractory to transduction with a GALV1 pseudotyped Moloney murine leukaemia virus (MoMLV)-based retroviral vector. In contrast, generation of DCs from purified CD34 progenitors was accompanied by rapid entry into the cell cycle and a 41.1-fold cell expansion at the end of 14 d culture.

Cooperative Regulation of NOTCH1 Protein-Phosphatidylinositol 3-Kinase (PI3K) Signaling by NOD1, NOD2, and TLR2 Receptors Renders Enhanced Refractoriness to Transforming Growth Factor-β (TGF-β)- or Cytotoxic T-lymphocyte Antigen 4 (CTLA-4)-mediated Impairment of Human Dendritic Cell Maturation

“…In addition to NOTCH signaling, a diverse set of signaling events, including the PI3K/AKT and MAPK pathways, as well as the active heterodimer p50/p65 form of nuclear factor-B (NF-B), have been suggested to play a central role in maturation of DCs by inducing expression of a variety of genes involved in maturation processes (45)(46)(47)(48). In this regard, engagement of TLR2 and NOD receptors triggered the activation of the PI3K pathway under CTLA-4-or TGF-␤-triggered immunosuppressive conditions as evaluated by phosphorylation status of p85, GSK-3␤, and 4EBP1 (Figs.…”

Activation of NF-κB by the intracellular expression of NF-κB-inducing kinase acts as a powerful vaccine adjuvant

“…Inhibition of NF-B blocks DC antigen presentation both in vitro and in vivo (6)(7)(8)(9)27), and inhibition of relB results in the generation of IL-10-producing regulatory T cells and antigenspecific tolerance in vivo (28). Indeed, many immunological adjuvants share their ability to activate NF-B among their multiple actions, but are often limited in use by their lack of specific, localized, and coordinated effects, and consequently by toxicity.…”

“…Recent observations have demonstrated that the transcription factor NF-B is essential for optimal DC function as inhibition of NF-B or its upstream activator I B kinase 2 (IKK2) blocks DC antigen presentation both in vitro and in vivo (6)(7)(8)(9). Several immunological adjuvants have been shown to activate NF-B among their multiple actions, but they are, however, limited in use by their lack of specific, localized, and coordinated effects and consequently by toxicity (10).…”

Cyclic AMP Modulates the Functional Plasticity of Immature Dendritic Cells by Inhibiting Src-like Kinases through Protein Kinase A-mediated Signaling

“…LPS has been shown to activate multiple signaling pathways in dendritic cells, including p38 SAPK and ERK (23). Activation of these kinases is associated with their phosphorylation and can be detected by Western blotting using phosphorylation-specific antibodies.…”