Microparticles of interferon gamma, which are attached to the macrophages, helped to keep the Pro-inflammatory M1 phenotype and resist the influence of cancer cells. Under the action of the microparticles M1 phenotype acquired and macrophages associated with the tumor. In the end, the tumor grew so much and gave less metastasis than in controls, and the animals lived longer. The work, published in the journal Science Advances, discoid microparticles called rucksacks — this form protects them from phagocytosis and allows you to stay on the surface of cells during at least two days.
In adoptive cell therapy the immune cells of the patient are isolated, modified and injected back. New properties of cells help them to more effectively fight tumors. The most successful example — CAR T-cell therapy in which T lymphocytes kill a chimeric tumor antigen receptor (CAR). In some cases, the treatment CAR T cells leads to complete recovery of patients with cancer, but this method works only against tumor cells that are not in solid tumors (e.g., in leukemia), and against cells that have specific receptors.
In contrast to T-lymphocytes, macrophages unable to kill a broader range of tumor cells, but they have the unpleasant property of the tumor unable to recruit these immune cells to its side. Depending on the substances that are in the environment, macrophages change phenotype: they can absorb pathogens (Pro-inflammatory M1 phenotype) or to regulate tissue homeostasis (anti-inflammatory M2 phenotype). The second property enjoyed by tumor cells: they secrete factors that cause the macrophages to acquire an M2 phenotype and promote tumor growth.