Donor Plasmacytoid Dendritic Cells Regulate GvHD in a VIP Dependent Manner in Allogeneic BMT Recipients

Introduction: Vasoactive intestinal peptide (VIP) is an anti-inflammatory neuropeptide known to induce differentiation of regulatory dendritic cells and regulatory T cells. Using allogeneic hematopoietic stem cell transplantation (allo-HSCT) models, we have shown that donor bone marrow (BM) plasmacytoid dendritic cells (pDCs) facilitate HSC engraftment and attenuate pathogenesis of graft vs. host disease (GvHD) through regulation of recipient T cells. However, the mechanism by which pDCs mitigate the GvHD activity of recipient T cells is not clearly understood. Here, we report that donor pDCs limit pathogenic T cell inflammation by VIP production.