categorized CD4+Treg infiltrating HNSCC into six subsets, with subsets 2 and 4 representing early-stage CD4+Treg with upregulated IFN-related signaling pathways, while subsets 3 and 6 represented late-stage CD4+Treg with upregulated TNF-related signaling pathways (42). Here, CD4 is linked to head and neck squamous cell carcinoma.