Gene expression changes in anti-FcgRIIb treated DCs and monocytes

The ability of dendritic cells (DCs) to activate immunity is linked to their maturation status. In prior studies we have shown that selective antibody-mediated blockade of inhibitory FcgRIIB receptor on human DCs in the presence of activating immunoglobulin (Ig) ligands leads to DC maturation and enhanced immunity to antibody-coated tumor cells. Here we show that Fcg receptor (FcgR) mediated activation of human monocytes and monocyte-derived DCs is associated with a distinct gene expression pattern, including several inflammation associated chemokines as well as type 1 interferon (IFN) response genes including the activation of signal transducer and activator of transcription 1 (STAT1). Keywords: response to antibody To further characterize FcgR mediated enhancement of DC function, we analyzed the gene expression profiles (GEP) of pure populations of monocyte-derived DCs from healthy donors (n=5) using Affymetrix Human Genome U133 Plus2.0 microarrays. Immature DCs cultured in 1% plasma were treated for 24 hours with either anti-FcgRIIB or isotype control antibody. To test whether FcgR mediated DC maturation was distinct from other maturation stimuli, we also compared DCs matured using the inflammatory cytokine cocktail (TNF-a, IL-1b, IL-6 and PGE2) commonly utilized in DC immunotherapy trials. In addition, we also treated Cd14+ monocytes (n=3) with anti-FcgRIIB antibody or isotype control. In order to better characterize the interferon responsive genes in DCs, we treated immature DCs (n=3) with 1000 U/ml of IFN-a2b.