In macaques (Macaca fascicularis), collagen I expression in the outermost area of granulomas is mediated by interleukins 4, 13 and transforming growth factor β (TGF-β) (Evans et al. 2020), indicating that macrophages present in the lesion contribute to fibrogenesis by stimulating myofibroblast activity indirectly at the periphery of stage III granulomas. Here, IL4 is linked to Granuloma.