[In vitro investigation on specific anti-leukemia cell effect of CTL induced by sensitized dendritic cells from...

This study was aimed to investigate the specific anti-leukemia cell effect of cytotoxic T lymphocytes (CTLs) induced by HL-60 or K562 cell-sensitized dendritic cells (DCs) from umbilical cord blood. 12 units of human umbilical cord blood (UCB) were collected and the mononuclear cells (MNCs) were isolated from UCB, then cultured with granulocyte monocyte colony- stimulating factor (GM-CSF), interleukin 3 (IL-3), recombinant human stem cell factor (SCF) and EPO for 3 - 4 weeks. Flow cytometry was used to determine the number of DCs and cell surface antigens before and after culture with monoclonal antibodies including CD83, CD1a, CD11c and CDw123. HL-60 and K562 were frozen-thawed, and released their tumor antigen peptides (TAP). The CTLs were produced by sensitizing T lymphocytes with DC-loaded HL-60 and K562 cell antigens. The test of (3)H-TdR incorporation was used to detect the immunostimulation activity of DCs. MTT assay was applied to evaluate specific cytotoxicity of CTL on leukaemia cells. The results indicated that the MNCs of UCBs cultured with GM-CSF, IL-3, EPO and SCF were shown to differentiate into CD1a(+) CD11c(+) CD83(+) CDw123(+) DCs. Numbers of DCs from UCBs remarkably increased in 2 - 4 weeks and then decreased. After culture with cytokines DCs increased (10.6 - 28.2) x 10(5)/ml in actual numbers. The CTL induced by DC pulsed with HL-60, K562 frozen-thawed lysates were effective to kill HL-60 and K562. Cytotoxicity of CTL to HL60 and K562 were (42.04 +/- 8.46)% and (31.25 +/- 11.07)% respectively. It is concluded that the MNCs of UCBs cultured with cytokines of GM-CSF, SCF, EPO and IL-3 can differentiate into CD1a(+), CD83(+), CD11c(+) and CDw123(+) DCs. The CTL induced by DCs pulsed with HL-60, K562 frozen-thawed lysates can effectively kill HL-60 and K562. These DCs as antigen presenting cells play an important role in cancer immunotherapy.