MPO and esophageal squamous cell carcinoma: IL-17-expressing CD4+ T cells were present in human esophageal squamous cell carcinoma (ESCC) tissues [118] and IL-17 could attract neutrophils by provoking the production of neutrophilic chemokines, CXCL2 and CXCL3, in ESCC cells and simultaneously activate neutrophils to express cytotoxic molecules, including MPO, TRAIL and IFN-γ, thereby inducing cancer cell death [119].