LAUSR

Significance The release of cytokines from various immune cells is known to be essential for successful muscle regeneration. However, the precise cellular origin of some of these cytokines and how they influence each other are still not clear. One such cytokine is IFNγ, which is most commonly thought to promote inflammation. Here, we show that IFNγ is primarily produced by a type of white blood cells called natural killer cells following muscle damage. In addition, we demonstrated that IFNγ cooperates with another cytokine, TNFα, in inducing the transition of macrophages from an inflammation-promoting phenotype to a regeneration-promoting phenotype. Therefore, the ways in which IFNγ regulates inflammation appear to be more diverse than previously believed.