CD4 and neoplasm: To enhance antitumour immune responses by CTLs and to inhibit the accumulation of immunosuppressive Treg cells in B16 tumours, we depleted CD4+ CD25+ FOXP3+ regulatory T (Treg) cells (Fig 1A), which have been shown to increase antitumour CD8+ T-cell responses in mice and in human patients, resulting in attenuated murine tumour growth (Ataera et al, 2011; Rech et al, 2012).