The purpose of the present invention is to provide, in order to continue the rejection of malignant tumors over a long period of time, an enhancer for endogenous T-cells or B-cells having a memory function, and a malignant tumor recurrence inhibitor. The present invention involves preparing: an enhancer for subject T-cells or B-cells having a memory function, said enhancer including a nucleic acid transportation medium, a nucleic acid encoding interleukin 7 (IL-7) and a nucleic acid encoding chemokine (C-C motif) ligand 19 (CCL 19)； an inducer which induces the memory function in the T-cells or B-cells in a subject； and a malignant tumor recurrence inhibitor which includes a nucleic acid transport medium, a nucleic acid encoding interleukin 7 (IL-7) and a nucleic acid encoding CCL19.本發明之目的在於為了長期持續排斥惡性腫瘤而提供一種具有記憶功能之內源性之T細胞或B細胞之增強劑及惡性腫瘤復發抑制劑。本發明製作一種投予對象中之具有記憶功能之T細胞或B細胞之增強劑、或對投予對象中之T細胞或B細胞誘導記憶功能之誘導劑，其包含核酸傳遞介質、編碼介白素7(IL-7)之核酸、及編碼趨化介素(C-C結構組元)配體19(CCL19)之核酸。又，本發明製作一種惡性腫瘤復發抑制劑，其包含核酸傳遞介質、編碼介白素7(IL-7)之核酸、及編碼CCL19之核酸。
