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Activation of plasmacytoid dendritic cells promotes AML-cell fratricide.

ABSTRACT: Acute myeloid leukemia (AML) is characterized by the proliferation of immature myeloid blasts and a suppressed immune state. Interferons have been previously shown to aid in the clearance of AML cells. Type I interferons are produced primarily by plasmacytoid dendritic cells (pDCs). However, these cells exist in a quiescent state in AML. Because pDCs express TLR 7-9, we hypothesized that the TLR7/8 agonist R848 would be able to reprogram them toward a more active, IFN-producing phenotype. Consistent with this notion, we found that R848-treated pDCs from patients produced significantly elevated levels of IFNβ. In addition, they showed increased expression of the immune-stimulatory receptor CD40. We next tested whether IFNβ would influence antibody-mediated fratricide among AML cells, as our recent work showed that AML cells could undergo cell-to cell killing in the presence of the CD38 antibody daratumumab. We found that IFNβ treatment led to a significant, IRF9-dependent increase in CD38 expression and a subsequent increase in daratumumab-mediated cytotoxicity and decreased colony formation. These findings suggest that the tolerogenic phenotype of pDCs in AML can be reversed, and also demonstrate a possible means of enhancing endogenous Type I IFN production that would promote daratumumab-mediated clearance of AML cells.

SUBMITTER: Fatehchand K

PROVIDER: S-EPMC8092344 | biostudies-literature |

REPOSITORIES: biostudies-literature

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STING mediates lupus via the activation of conventional dendritic cell maturation and plasmacytoid dendritic cell differentiation

Project description:BMDCs from WT, Fcgr2b-/- and Stinggt/gt were cultured, then stimulated with DMXAA for 3 and 6 hr. Cells were collected and lysed with 1 % IGEPAL CA-630, 0.5% TritonX-100, 150 mM NaCl, 50 mM Tris pH 7.4, 5% glycerol, 100 mM beta-Glycerophosphate, 2 mM Na3VO4 and 1X proteases inhibitor cocktail (Roche). First, antibody were mixed with the magnetic beads by adding 10 µg of STING antibody with 400 ug of SureBeads™ Protein A magnetic beads (Biorad, California, USA) and incubated for 1 hour at room temperature. Then, Protein lysates were added and incubated with antibody-conjugated beads for overnight at 4oC. After incubation, the beads were washed 3 times with wash buffer (150 mM NaCl and 50 mM Tris-HCL pH 7.4). Samples were eluted by adding 5X laemmli buffer and, boiled 950C for 10 minutes. The eluted protein samples were separated by 10 % SDS-PAGE gel. The STING interacting proteins from co-IP were analyzed by in-gel digestion followed by LC-MS/MS analysis.

2020-09-14 | PXD019239 | Pride

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