Objective    To investigate the effect of vascular endothelial growth factor (VEGF) on antigen presentation capability of dendritic cells (DCs) derived from leukemic cell line.     Methods    After treated by 5 μmol/L VEGF antisense oligodeoxynucleotide (AS-ODN) for 24 h

VEGF protein expression of K562 cells was measured by ELISA and immunohistochemistry. Taking DCs induced from K562 as control

the biological characteristics of leukemic DCs derived from K562 treated by AS-ODN were examed. Flow cytometry was used to detect the expressions of immunophenotypes. The proliferative ability of T cells stimulated by DCs was analyzed by mixed lymphocyte reaction assay. Moreover

luciferase assay system was used to monitor the transcription activity of NF-κB and RT-PCR to detect Flt-1 mRNA expression at the end of 12-hour culture.     Results    VEGF protein secretion of treated K562 decreased remarkably compared to K562 cell (P<0.05). Compared to K562-DC group

the expressions of immunophenotypes including CD40

CD83

CD86 and HLA-DR in leukemic DCs group increased remarkably. The stimulating index (SI)of MLR in leukemic DCs group was significantly higher than that in the control group in different ratio of DC/T (1∶10 to 1∶40) respectively (P<0.05). At the end of 12-hour culture

the transcription activity of NF-κB of leukemic DCs was significantly higher (P<0.05)

but Flt-1 mRNA level had no obvious change.     Conclusion    VEGF AS-ODN could inhibit VEGF protein level in  leukemic cells in vitro. Downregulating VEGF could enhance the immunophenotype expressions of DCs derived from the leukemic cells and improve their antigen presentation capability.