CD4 and neoplasm: CD4+/CD25+/CD127low Treg made up a significantly larger proportion of T cells in tumor samples (10.3 ± 6.3%) compared to PBMC HNSCC (3.7 ± 2.0%; p < 0.0001) and non-cancerous mucosa (4.2 ± 4.4%, p < 0.05; Figure 1E, left plot).