Dendritic Cells (DCs) are specialized antigen presenting cells (APCs) that have attracted much attention in recent years and are capable of uptake, processing and presentation of antigens to initiate T cell-mediated immune responses. For a long time afterwards, it was not possible to grow more dendritic cells in vitro due to the limitations of biological technology at that time, and it was expensive, which prevented further research on it. In the 1990s, we made great progress in biological technology and were able to cultivate dendritic cells in vitro, which led to a breakthrough in the study of DCs. At the end of the twentieth century, the United States was the first country to start experiments on dendritic cell immunotherapy for tumors in humans. The results were very encouraging. What followed was that dendritic cells became the star of tumor biotherapy and a hot topic of research for scientists fighting cancer around the world. Dendritic cells are the sentinels of the human immune system, which can sharply capture the minute differences between tumor cells and normal cells, and deliver these differences to the T-lymphocytes in the human immune system, so that the T-lymphocytes can receive the methods and orders of battle to identify the rebels and quickly transform from the resting state to the battle state, and eliminate all the remaining and metastatic cancer cells in the human body. Moreover, T-cell immunity has the ability to remember, which means that if the same cancer cells arise again in a person’s lifetime, the body’s immune system will immediately finish off the cancer cells. This is why dendritic cell immunotherapy is also known as a therapeutic vaccine (as opposed to the preventive vaccines we use every day). When it comes to dendritic cell immunotherapy, it is not complicated: the tumor patient is given a 2~3 days mobilization agent, which allows the immature stem cells in the human bone marrow to run out into the blood. The tumor antigens (tumor antigen peptides can be synthesized artificially without tissues) from the patient’s original cryopreserved tumor tissues are then co-cultured together, so that the dendritic cells can take on the tumor information and then injected back to the patient, and the dendritic cells in the body can awaken the body’s dormant immune system to kill cancer cells (the tumor patient’s own DC cannot recognize cancer cells in the body).