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. Author manuscript; available in PMC: 2018 Jul 1.
Published in final edited form as: Nat Rev Clin Oncol. 2017 Jan 24;14(7):399–416. doi: 10.1038/nrclinonc.2016.217

Figure 2. Bimodal function of TAM in response to chemotherapy and radiotherapy.

Figure 2

Macrophages orchestrate immune responses that can either hamper (left) or foster (right) the effectiveness of conventional anticancer strategies.

On the left: cytotoxic agents enhance tumor infiltration by immunosuppressive macrophages, which activate chemoprotective T cells and tame adaptive immune responses; chemotherapy or radiotherapy-induced tissue damage triggers the recruitment of immunosuppressive myeloid cells, which orchestrate a misdirected tissue-repair response, promoting tumor growth and revascularization; macrophages, an essential component of tissue stem cell niches, can protect CSC against cytotoxicity.

On the right: selected chemotherapeutic agents (e.g Doxorubicin) increase the immunogenicity of malignant cells (immunogenic cell death), which stimulate myeloid cells to differentiate into antigen presenting cells and trigger effective adaptive immune responses; anticancer agents like Gemcitabine can directly skew macrophage effector functions towards an antitumor mode and increase their cytotoxicity, resulting into a favorable synergism; neoadjuvants low-dose γ-irradiation set macrophage functions in an antitumor mode, promoting regression at sites distant from irradiated lesions (abscopal effect). CSC: cancer stem cells.