Macrophages dynamically regulate GVHD progression via M1/M2 polarization: M1 macrophages secrete pro-inflammatory factors such as tumor necrosis factor (TNF)-α, IL-1β, and IL-6 that exacerbate tissue damage; meanwhile M2 macrophages secrete anti-inflammatory cytokines like IL-10 and TGFβ that inhibit inflammation while promoting repair processes [16,17]. Here, IL1B is linked to graft versus host disease.