CD4 and neoplasm: Recent reports have demonstrated that ligation of Tim-3 ligand and Tim-3 expressed on CD4 + T cells inhibits TCR signaling in T cells and that Tim-3-expressing Foxp3 + regulatory T cells that have enhanced regulatory function play a key role in preventing effective CTL induction and T cell tolerance (Das M, et al. Tim-3 and its role in regulating anti-tumor immunity.