NET-producing CD16high CD62Ldim neutrophils migrate to tumor sites and predict improved survival in patients with HNSCC

The concept of functional neutrophil subsets is new and their clinical significance in malignancies is unknown. Our study investigated the role of CD16(dim) CD62L(high), CD16(high) CD62L(high) and CD16(high) CD62L(dim) neutrophil subsets in head and neck squamous cell carcinoma (HNSCC) patients. These neutrophil subsets may play different roles in immune-related activity in cancer, based on their profile, activation state and migration ability within a tumor site, which may be important in predicting cancer prognoses. Tumor biopsies and blood were obtained from newly diagnosed untreated HNSCC patients and healthy controls. Neutrophil subsets and their phenotype were characterized using flow cytometry. Isolated granulocytes were assessed for anti-tumor immune functions. Compared to controls HNSCC patients exhibited increased CD16(high) CD62L(dim) neutrophils in blood; this subset displayed a distinct phenotypes with high expression of CD11b and CD18. This subset was prone to migrate into the tumor facilitated by tumor-derived IL-8. Furthermore, IL-8 was also found to activate neutrophils and thereby promoting subset transition. Various assays demonstrated that activated CD16(high) CD62L(dim) neutrophils inhibited migration, proliferation and induced apoptosis of FaDu cancer cells. Neutrophil elastase detected in activated CD16(high) CD62L(dim) neutrophils and tumor biopsies suggested that CD16(high) CD62L(dim) neutrophils impart anti-tumoral activity via neutrophil extracellular traps. Furthermore, increased fraction of CD16(high) CD62L(dim) neutrophils was shown to correlate with an increased survival rate. Our study demonstrates the clinical relevance of the CD16(high) CD62L(dim) neutrophil subset, providing evidence for its increased migration capacity, its anti-tumor activity including increased NET formation and finally its correlation with increased survival in HNSCC patients. What's new? Evidence is growing for distinct neutrophil subsets with diverse roles in cancer immunology, but a clinical link remains to be established. Our study demonstrates the clinical relevance of the CD16(high) CD62L(dim) neutrophil subset in head and neck squamous cell carcinoma (HNSCC). Patients harbored an increased fraction of anti-tumorigenic CD16(high) CD62L(dim) neutrophils in the circulation compared to healthy controls. The subset had an enhanced capacity to elicit neutrophil extracellular traps (NETs) extrusion, and an increased fraction of CD16(high) CD62L(dim) neutrophils in the circulation correlated with increased survival. The findings demonstrate an anti-tumoral role of the CD16(high) CD62L(dim) neutrophil subset in HNSCC.