Tumor-Promoting Ly-6G+ SiglecFhigh Cells Are Mature and Long-Lived Neutrophils

Myeloid cells co-expressing the markers CD11b, Ly-6G, and SiglecF can be found in large numbers in murine lung adenocarcinomas and accelerate cancer growth by fostering tumor cell invasion, angiogenesis, and immunosuppression; however, some of these cells' fundamental features remain unexplored. Here, we show that tumor-infiltrating CD11b + Ly-6G + SiglecF high cells are bona fide mature neutrophils and therefore differ from other myeloid cells, including SiglecF high eosinophils, SiglecF high macrophages, and CD11b + Ly-6G + myeloid-derived suppressor cells. We further show that SiglecF high neutrophils gradually accumulate in growing tumors, where they can live for several days; this lifespan is in marked contrast to that of their SiglecF low counterparts and neutrophils in general, which live for several hours only. Together, these findings reveal distinct attributes for tumor-promoting SiglecF high neutrophils and help explain their deleterious accumulation in the tumor bed.