Tumor-associated neutrophils and macrophages differentially affect T cell biology in the head and neck cancer tumor microenvironment.

Intra-tumoral T cell activity is required for effective anti-tumor immune responses and is partly regulated by tumor-associated neutrophils and macrophages. Here, we investigated the spatial context of neutrophil/macrophage interactions with CD8+ T cells in head and neck squamous cell carcinoma. Using multiplex immunofluorescence staining of biopsies from 14 patients, we analyzed neutrophils, macrophages, and CD8+ T cells within tumor nests and stromal compartments. All three cell types were enriched in the stroma. To characterize spatial immune niches, we defined regions enriched for each cell type and analyzed their overlap. CD8+ T cells showed spatial exclusion from neutrophils, whereas macrophages co-localized with CD8+ T cells. In regions enriched for both neutrophils and CD8+ T cells, neutrophils were associated with reduced CD8+ T cell proliferation, potentially caused by contact-dependent suppression. These findings demonstrate that neutrophils and macrophages differentially shape CD8+ T cell distribution and activity within the head and neck cancer microenvironment.