IFNG and Crohn disease: In addition, recent studies have shown that unique subsets of macrophages in the intestinal mucosa contribute to the pathogenesis of Crohn’s disease via the IL-23/IFN-γ axis and increased Th17-inducing activity; particularly, IL-23, released by macrophages, activates signal transducer and activator of transcription (STAT-) 4 signalling in memory T lymphocytes, driving IFN-γ production.