Impact of Antigen-unloaded Immature Dendritic Cells on Antileukemic T-Cell Cytotoxicity

Background: Immature dendritic cells (iDC) loaded with antigens are able to induce tolerance in antigen-specific T-cells. The potential of antigen-unloaded iDC to regulate the antileukemic cytotoxicity of autologous T-cells was determined. Materials and Methods: iDC generated with 50 U/ml granulocyte-macrophage colony-stimulating factor (GM-CSF) and very immature DC (viDC) generated with 10 U/ml GM-CSF from the bone marrow of Balb/c mice were used for T-cell co-culture. Results: The measurement of cellular cytotoxicity against the syngeneic murine B-cell leukemia line A20 revealed that T-cells without co-culture or after co-culture with iDC exerted a similar cytotoxicity, whereas T-cells co-incubated with viDC showed a significantly diminished lysis of A20 cells (p<0.05). Conclusion: Antigen-unloaded iDC in contrast to antigen-loaded iDC may not affect antileukemic T-cell cytotoxicity, whereas antigen-unloaded DC cultures generated with a low dose of GM-CSF are able to impair the T-cell-mediated cytolysis of leukemic cells.