These data suggest that iNOS+Arg1+ macrophages mediate bacterial control in hematopoietic Stat2−/− BMC (WT host/ Stat2−/− BM) and Stat2−/− BMC mice (Stat2−/− host/Stat2−/− BM) during influenza-MRSA super-infection. The gene discussed is NOS2; the disease is influenza.