From the current research, we have discovered and confirmed for the first time that there are neutrophils with high expression of B7‐H2 in GC tissues and are significantly related to the prognosis of GC patients; it is also the first authentication for tumor‐derived TNF‐α to activate neutrophils which polarize protumorigenic IL‐17A‐producing Th subsets linking mechanistically the pathological roles of B7‐H2+ neutrophils in GC environment. The gene discussed is IL17A; the disease is gastric cancer.