Given that a higher T-cell proportion was associated with improved survival in HNSCC patients and that our prior scRNA-seq dataset included a relatively large number of T-cells (~1000 T-cells), we next examined T-cell subtypes by finer clustering, producing four sub-clusters annotated by marker genes [8] as conventional CD4 T-cells (CD4conv; CCR7, TCF7), regulatory T-cells (Tregs; FOXP3, CD25), conventional CD8 T-cells (CD8conv; GZMA/B/H/K, PRF1), and exhausted CD8 T-cells (CD8exhausted; PD1, LAG3, TIGIT, CTLA4) (Figure 3A). Here, PRF1 is linked to head and neck squamous cell carcinoma.