PGE₂ restores proliferation and granulocyte differentiation in HSPCs lacking MyD88 or TLR2. (A) BM HSPCs were incubated for 48 hours in vitro with either heat-killed (HK) S aureus, indomethacin and HK S aureus, or PGE₂. BrdU was added for the last 12 hours of incubation to quantify cell proliferation. Data represent 7 to 8 mice per group during 3 experiments and are expressed as a percentage of baseline BrdU incorporation. (B) BM HSPCs from Lys-EGFP WT mice or Lys-EGFPMyD88^−/− mice were adoptively transferred into wounds of WT mice with S aureus infection. A third group of mice received HSPCs from Lys-EGFP/MyD88^−/− mice that were preincubated with PGE₂ before transfer. Total EGFP-PMN signal 7 days after transfer is plotted as a read-out for PMN production. Data represent 3 mice per group. (C) BM HSPCs from CD45.2⁺ C57BL/6 or TLR2-deficient mice were enriched and transferred to the infected wounds of congenic CD45.1⁺ mice. A third group received HSPCs from TLR2-deficient mice that were preincubated with PGE_2. The number of donor-derived PMNs was determined via flow cytometry and was plotted relative to PMNs produced by donor WT HSPCs. Data represent 4 to 5 mice per group. All data shown as mean ± SEM (*P < .05; ***P < .001).