IFNG and infection: Moreover, in wild-type mice we detected only a very small proportion of T cells (CD8b+) and NK cells (NK1.1+) within the peritoneal population of IFN-γ+ cells 12 h after infection (Supplementary Figure S3B); thus, phagocytes—rather than NK cells or T cells—are the principal source of IFN-γ in the early stages of peritoneal infection.