Leukemia-associated activating mutation of Flt3 expands dendritic cells and alters T cell responses
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ABSTRACT: One of the most common genetic alterations in acute myeloid leukemia is the internal tandem duplication (ITD) in the FLT3 receptor for cytokine FLT3 ligand (FLT3L). The constitutively active FLT3-ITD promotes the expansion of transformed progenitors, but also has pleiotropic effects on normal hematopoiesis. We analyzed the effect of FLT3-ITD on dendritic cells (DCs), which express FLT3 and can be expanded by FLT3L administration. We report that young pre-leukemic mice with the Flt3ITD knock-in allele manifest an expansion of all DCs including classical (cDCs) and plasmacytoid (pDCs). The expansion originated in DC progenitors, occurred in a cell-intrinsic manner and was further enhanced in Flt3ITD/ITD mice. The mutation caused the downregulation of Flt3 on the surface of DCs and reduced their responsiveness to Flt3L. Flt3ITD mice showed enhanced capacity to support T cell proliferation, including a cell-extrinsic expansion of regulatory T cells (Tregs). Accordingly, these mice restricted alloreactive T cell responses during graft-versus-host reaction, but failed to control autoimmunity in the absence of Tregs. Thus, the FLT3-ITD mutation directly affects DC development, thereby indirectly modulating T cell homeostasis and supporting Treg expansion. This effect of FLT3-ITD may subvert immunosurveillance and promote leukemogenesis in a cell-extrinsic manner.
ORGANISM(S): Mus musculus
PROVIDER: GSE76132 | GEO | 2016/01/28
SECONDARY ACCESSION(S): PRJNA306390
REPOSITORIES: GEO
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