Which macrophage phenotype is often associated with immune suppression in tumors?

Which macrophage phenotype is often associated with immune suppression in tumors?

• A. M1 macrophages
• B. M2-like tumor-associated macrophages
• C. Alveolar macrophages
• D. Microglia

Answer: (B)

The key idea is how macrophage polarization shapes the tumor environment. Macrophages can become either pro-inflammatory and anti-tumor (M1) or anti-inflammatory and pro-tumor (M2-like). In many tumors, signals from cancer and stromal cells—like IL-4, IL-10, TGF-β, and CSF-1—drive macrophages toward an M2-like, tumor-associated state. These cells express markers such as CD206 and CD163 and secrete IL-10 and TGF-β, which dampen cytotoxic T cell activity. They also promote angiogenesis with VEGF and remodel the extracellular matrix, creating an environment that favors tumor growth and hinders immune attack. Because of these activities, M2-like tumor-associated macrophages are closely linked with immune suppression in tumors. While M1 macrophages are inflammatory and anti-tumor, and alveolar macrophages or microglia are specialized resident macrophages, the M2-like TAMs are the ones most consistently associated with immune suppression in the tumor setting.

The key idea is how macrophage polarization shapes the tumor environment. Macrophages can become either pro-inflammatory and anti-tumor (M1) or anti-inflammatory and pro-tumor (M2-like). In many tumors, signals from cancer and stromal cells—like IL-4, IL-10, TGF-β, and CSF-1—drive macrophages toward an M2-like, tumor-associated state. These cells express markers such as CD206 and CD163 and secrete IL-10 and TGF-β, which dampen cytotoxic T cell activity. They also promote angiogenesis with VEGF and remodel the extracellular matrix, creating an environment that favors tumor growth and hinders immune attack. Because of these activities, M2-like tumor-associated macrophages are closely linked with immune suppression in tumors. While M1 macrophages are inflammatory and anti-tumor, and alveolar macrophages or microglia are specialized resident macrophages, the M2-like TAMs are the ones most consistently associated with immune suppression in the tumor setting.