An important role for granulocyte-derived IL-10 in promoting S. aureus craniotomy infection was established using Mrp8CreIL-10 fl/fl mice that displayed decreased bacterial burden that was likely due, in part, to IL-10 production by G-MDSCs that inhibited polymorphonuclear neutrophil (PMN) bactericidal activity and TNF expression. This evidence concerns the gene IL10 and infection.