CD4 and head and neck squamous cell carcinoma: It was reported that the prevalence of NRP1+ Tregs is associated with reduced progression-free survival in head and neck cancer [135,136]; however, conversely, some studies indicate that high levels of Foxp3+ Treg infiltration in HNSCC were associated with longer recurrence free survival (RFS) and overall survival (OS), which was associated with the presence of high levels of CD4+CD25+Foxp3+Treg in TILs.