CD4 and neoplasm: Remarkably, the increased levels of CD4+CD25+ Tregs and PD-1+ T cells correlated positively to better clinical prognosis in HNSCC patients (Badoual et al., 2006, 2013; Loose et al., 2008), which is different from the common observation of elevated Tregs in association with immunosuppression and poor clinical outcomes in other tumor types.