Abstract: Objective The TNF-related apoptosis-inducing ligand is currently under evaluation as a possible(co^-)therapeutic in cancer treatment,and it can notably induce the apoptosis of the tumor cells.To study the effect of TRAIL on leukemic cells of the patients,we have investigated the susceptibility of 13 acute leukemic cell samples from acute leukemic patients to TRAIL-induced apoptosis in vitro.Moreover,13 cell samples are coincubated with Ara-C in order to research the synergy between TRAIL and anti-cancer drug.Methods Thirteen leukemic cell samples were from acute leukemic patients who cared in Beijing Friendship Hospital from September 2002 to January 2003.The cell samples contained more than 60% leukemic cells based on morphology criteria.Every cell sample was separated into 4 groups:control group,TRAIL group,Ara-C group,TRAIL+Ara-C group.The cell samples were cultured 24 hours and the apoptotic cells were analyzed by flow cytometry after stained with Annexin Ⅴ and PI.Results Control group:the apoptotic cells were(10.22±7.48)%,TRAIL group:the apoptotic cells were(14.61±11.95)%,Ara-C group:(15.95±11.12)%,TRAIL+Ara-C group:(22.11±15.97)%.There were not significant statistically differences in three groups:control group and TRAIL group(P=0.35),TRAIL group and TRAIL+Ara-C group(P=0.12),Ara-C group and TRAIL+Ara-C group(P=0.19).There was just statistically difference between control group and TRAIL+Ara-C group(P=0.015).Furthermore,3 of 13(15%) cell samples revealed at least 10% TRAIL-susceptibility cells.Coincubated with Ara-C sentitized 2 initially TRAIL-resistant samples to TRAIL-induced apoptosis(>20% specific TRAIL-induced apoptotic cells).Conclusion 1) Only 23% leukemic cell samples are TRAIL sensitive cases;2) Coincubated with TRAIL and Ara-C augmented apoptosis in leukemic cells,including initially TRAIL-resistant samples.

Key words: TNF-related apoptosis-inducing ligand, acute leukemia, cell apoptosis, flow cytometry