SLAMF9 promotes inflammation and resistance to Salmonella infection

SLAMF9 is an uncharacterized member of the CD2/SLAM family of cell surface receptors. Unlike other members of the SLAM-family, it contains no phosphorylated tyrosines or recognizable signaling motifs, and neither homotypic nor heterotypic interactions between SLAMF9 and other members of the SLAM family have yet been observed. Through generation of Slamf9 −/− mice and novel antibody reagents, we have determined that SLAMF9 is expressed on plasmacytoid dendritic cells, B1 cells, and select populations of tissue-resident mononuclear phagocytes. RNA interference experiments in human THP-1 monocytes indicate that SLAMF9 is important in the production of pro-inflammatory cytokines following stimulation with TLR agonists, and infection of Slamf9−/− mice demonstrate the importance of SLAMF9 in clearance of systemic Salmonella Typhimurium infection.