Gastric tumor infiltrated Tregs exhibit a higher affinity for CCL17/22 than effector T cells, and the level of chemokines CCL17/22 produced by DC cells in gastric tumors was significantly higher than normal gastric mucosa which induce the migration of Tregs in peripheral sites via CCR4 (the receptor for CCL17/22). The gene discussed is CCL17; the disease is gastric neoplasm.