Abstract
BACKGROUND: The tumor microenvironment of oropharyngeal squamous cell carcinoma (OPSCC) harbors diverse immune cell populations that influence tumor progression and patient outcome. MATERIALS: In 102 surgically treated OPSCCs, we determined HPV/p16 status by immunohistochemistry and RNA in situ hybridization. We analyzed mRNA transcripts using the PanCancer IO360 panel by NanoString. Multiplex immunohistochemistry/immunofluorescence was performed to characterize monocytic (M-MDSC, CD11b⁺CD14⁺HLA-DR(low/−)CD15(−)) and polymorphonuclear myeloid derived suppressor cells (PMN-MDSC, CD11b⁺CD14(−)HLA-DR(low/−)CD15(+)), M1-like (CD68⁺iNOS⁺) and M2-like macrophages (CD68⁺CD206⁺), B cells (CD20⁺), T helper cells (CD3⁺CD4⁺), and cytotoxic T cells (CD3⁺CD8⁺) in the tumor (TC) and stroma compartment (SC) of the primary tumor (PT) and the lymph node metastases (LM). RESULTS: Transcriptomic profiling revealed higher lymphoid compartment and antigen presentation scores in HPV/p16⁺ OPSCC (p = 0.002, p = 0.020, respectively), consistent with increased tumor-infiltrating lymphocytes (p = 0.025). HPV/p16– OPSCC exhibited higher myeloid compartment scores (p < 0.001). M2-like macrophages and M-MDSCs were significantly enriched in PT, while M1-like macrophages and PMN-MDSCs predominated in LM (p < 0.001 each). In HPV/p16 + OPSCC, M1-like macrophages, cytotoxic T and B cells were increased (p < 0.001, p < 0.001, p = 0.050, respectively), whereas MDSC frequencies were comparable between both HPV/p16 subgroups. Higher PMN-MDSC infiltration was correlated with poorer overall survival (OS, p = 0.050), while increased T helper, cytotoxic T, and B cell infiltration predicted improved OS (p = 0.009, p < 0.001, p = 0.005, respectively). CONCLUSION: HPV/p16 + OPSCCs exhibit a lymphoid-dominant, antigen-presenting immune phenotype, whereas HPV/p16– tumors display a myeloid-dominated TME. Despite similar MDSC frequencies, transcriptional and spatial analyses suggest functional divergence of myeloid lineages and local immune differentiation between primary and metastatic sites. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s10020-026-01481-w.