Based on the IL‐33 levels in this study and their association with the enhanced infiltration of local M2 macrophage in ESCC tumours, we investigated whether IL‐33 could induce the M0‐to‐M2 macrophage differentiation by treating the M‐CSF–induced PBMC‐derived macrophages with IL‐33. Here, CSF1 is linked to esophageal squamous cell carcinoma.