Background: Bone metastasis is a common complication of certain types of cancer, and
unfortunately, it is still incurable to date. Immune system is a major defence against tumor cells and
bone metastasis. However, the immunodeficient mouse models are widely used in most researches of
bone metastasis, thereby excluding the regulatory roles of the immune system in bone metastasis.
Objective: The aim was to provide a comprehensive overview on the cellular and molecular mechanisms
by which immune cells interact with tumor cells and bone cells, as well as recent related patents.
Method: We performed a literature search of PubMed database for the current knowledge on the interaction
between bone metastasis and immune system. Recent related patents were obtained from World
Intellectual Property Organization (WIPO) website.
Results: Immune cells in the bone-tumor microenvironment include dentritic cells, monocytes/
macrophages, myeloid-derived suppressor cells, regulatory T cells, T helper cells, neutrophil,
CD4+ T lymphocytes, CD8+cytotoxic T lymphocytes, and natural killer cells, et al. In addition to their
well-known immunomodulatory function, recent studies revealed that immune cells could cooperate
with tumor cells and bone cells to enhance bone metastasis and tumor progression. There are some
patents targeting immune system to inhibit bone metastasis.
Conclusion: Immune cells are instigated by tumor cells to enhance the occurrence and the development
of bone metastasis. Taking full advantage of anti-tumor roles of immune cells may bring the
promise of a possible cure for bone metastasis.