Elevated phagocytosis of bacteria by TREM-2 deficient AM. SharifOmar GawishRiem M. WarszawskaJoanna MartinsRui LakovitsKarin HladikAnastasiya DoningerBianca BrunnerJulia KorosecAna E. SchwarzenbacherRoland BergTiina KralovicsRobert ColingeJacques MesteriIldiko GilfillanSusan SalmaggiAndrea VerschoorAdmar ColonnaMarco KnappSylvia 2014 <p>(<b>A</b>) WT and <i>Trem-2</i><sup>−/−</sup> BMDM (n = 4–5 per genotype) were incubated with FITC labeled <i>S. pneumoniae</i> (MOI 100) and after 1 h phagocytosis was assessed using FACS. (<b>B–C</b>) WT and <i>Trem-2</i><sup>−/−</sup> AM (n = 4 per genotype) were incubated with FITC labeled <i>S. pneumoniae</i> (<b>B</b>) or <i>E. coli</i> (<b>C</b>) (MOI of 100) and phagocytosis was assessed using FACS 1 h later. (<b>D</b>) Elevated phagocytosis of <i>S. pneumoniae</i> by <i>Trem-2</i><sup>−/−</sup> AM as determined using confocal microscopy as described in the M&M section. The percentage of cells that contain bacteria is depicted (n = 4–5 per genotype). (<b>E–F</b>) WT and <i>Trem-2</i><sup>−/−</sup> AM (n = 4–5 per genotype) were incubated with FITC labeled <i>S. pneumoniae</i> (MOI 100) under either serum free conditions (SFM) or the bacteria were pre-opsonised with 10% anti-pneumococcal serotype III capsular antibody (ST3-Ab) (<b>E</b>) or 10% pooled WT mouse serum (<b>F</b>) for 30 min before addition to the cells. Phagocytosis was assessed 1 h later. (<b>G</b>) WT and <i>Trem-2</i><sup>−/−</sup> AM (n = 4 per genotype) were incubated with 1 µg/ml FITC labeled BSA or FITC labeled <i>S. pneumoniae</i> (MOI 100) and phagocytosis was assessed 1 h later by FACS. (<b>H</b>) WT and <i>Trem-2</i><sup>−/−</sup> AM (n = 4 per genotype) were incubated with FITC labeled <i>S. pneumoniae</i> strain 19A (MOI 100) and phagocytosis was assessed 1 h later by FACS. (<b>I–L</b>) WT and <i>Trem-2</i><sup>−/−</sup> mice (n = 7 mice per genotype) were intranasally infected with 10<sup>6</sup> CFU FITC labeled <i>S. pneumoniae</i> for 4 h and in vivo phagocytosis by AM (<b>I–J</b>) and neutrophils (<b>K–L</b>) was determined. <b>J</b> and <b>L</b> show representative FACS plots of data in <b>I</b> and <b>K</b>. (<b>M</b>) WT and <i>Trem-2</i><sup>−/−</sup> mice (n = 6 mice per genotype) were intranasally infected with 10<sup>5</sup> CFU <i>S. pneumoniae</i> and bacterial CFUs were enumerated 24 h post infection in the lung and BALF. All data represent mean ± SEM versus WT unless otherwise indicated. Data in (<b>A–C, F and H</b>) are representative of three independent experiments and all other data are representative of two independent experiments. * p<0.05, ** p<0.005, **** p<0.0001.</p>