Overlapping MHC class I/II Epitopes Program cDC1-like Differentiation of Monocyte-Derived Dendritic Cells via mTORC1 Signaling Inhibition

Viral infection polarizes monocyte-derived dendritic cells (moDC) to initiate type 1 immunity. The availability of overlapping (homologous) MHC class I and II epitopes, an occurrence frequently and primarily associated with intracellular infection, significantly enhances this process; however, the underlying mechanism(s) are unclear. We demonstrate that moDC loaded with homologous MHC epitopes acquire a cDC1-like phenotype in a process governed by mTORC1. mTORC1 pathway inhibition leads to NF-{kappa}B-mediated expression of IL-12 and other type I immune polarizing genes. The observed cDC1-like gene signature was also significantly enhanced in clinical moDC vaccine products made through methodologies that enforced class I and II antigenic homology. Collectively, these findings reveal a novel and previously unrecognized mechanism of immune governance that might also be exploited in cancer immunotherapy. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=167 SRC="FIGDIR/small/716309v1_ufig1.gif" ALT="Figure 1"> View larger version (41K): org.highwire.dtl.DTLVardef@15475borg.highwire.dtl.DTLVardef@ffe5fborg.highwire.dtl.DTLVardef@53c761org.highwire.dtl.DTLVardef@46c4ef_HPS_FORMAT_FIGEXP M_FIG C_FIG