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 cells are bona fide mature neutrophils and therefore differ from other myeloid cells, including SiglecF eosinophils, SiglecF macrophages, and CD11b Ly-6G myeloid-derived suppressor cells. We further show that SiglecF neutrophils gradually accumulate in growing tumors, where they can live for several days; this lifespan is in marked contrast to that of their SiglecF counterparts and neutrophils in general, which live for several hours only. Together, these findings reveal distinct attributes for tumor-promoting SiglecF neutrophils and help explain their deleterious accumulation in the tumor bed.