Possible functions of CD169‐positive sinus macrophages in lymph nodes in anti‐tumor immune responses

The lymph node (LN) is an important immune system in which a number of antigen‐presenting cells are present that induce rapid immune responses to foreign antigens. While a great number of macrophages exist in lymph nodes, recent studies using animal models have shown that lymph node sinus macrophages are associated with the induction of anti‐tumor immunity, playing a significant role in host immune responses against tumor cells. In colorectal tumor, malignant melanoma, and endometrial tumor, it was shown that a high density of CD169‐positive macrophages in the LN sinus was a predictive factor for better clinical prognosis. The observations that the density of CD169‐positive macrophages in the LN sinus was positively associated with the density of infiltrating T or NK cells in tumor tissues, indicates the significance of CD169‐positive macrophages in anti‐tumor immune reactions of tumor patients. Moreover, antigen delivery targeting LN macrophages is also considered to be promising approach for vaccination. In this article, we have summarized the significance of CD169‐positive LN macrophages in anti‐tumor immunity.