CD4 and head and neck squamous cell carcinoma: A study by Bergmann et al. in TILs and PBMC of HNSCC patients demonstrated a significant increase in the frequency and inhibitory activity of CD4+CD25−Foxp3+ T cells in patients presenting with advanced stages and it was suggested that the tumor microenvironment may have a role in the induction of CD4+CD25−Foxp3+ T cells within tumor [84].