Tumor-associated neutrophils: friend or foe?

Neutrophils play an established role in host defense and in killing invading microorganisms. Although neutrophils are traditionally considered in the context of their antibacterial functions, it is becoming increasingly clear that tumor-associated neutrophils (TAN) play a major role in cancer biology. Neutrophils make up a significant portion of the inflammatory cell infiltrate in many models of cancer. Like all other leukocytes, they move into tissues under the influence of specific chemokines, cytokines and cell adhesion molecules. The tumor microenvironment has been shown to be responsible for their recruitment in cancer. We have found that TAN are a distinct population of neutrophils, differing markedly in…