AIM: To study the effects of WT1 peptide-loaded dendritic cells (DC) stimulating the cytotoxic T lymphocytes (CTL) on K562 cells in vitro. METHODS: DC were generated from normal human peripheral blood mononuclear cells (PBMC) in the presence of granulocyte-macrophage colony stimulating factor(GM-CSF), interleukin-4 (IL-4) and tumor necrosis factor alpha (TNF-?) , DC were cultured with WT1 peptides , and then triggered T cells into specific CTL. RESULTS: Most suspended cells exhibited distinctive morphological features of DCs and they stimulated proliferation of allogenic lymphocytes. Under the effector : target ratio of ~20∶1 , CTLs derived from cultures with DC and WT1 peptides were showed 86.1%?26.8% cytotoxicity against K562 cells, cytotoxicity by CTLs derived from cultures with unloaded DC against K562 cells were 47.1%?20.8% and cytotoxicity by lymphocytes were 27.7%?15.3%. Cytotoxicity by CTLs derived from culture with WT1 peptides-loaded DC were the strongest among three groups (P