Background : Fas antigen is a cell surface protein elonging to the tumor necrosis factor/nerve growth factor receptor superfamily. Activation of Fas by its ligand Results in transduction of a signal for apoptosis. Leukemic cells often die by apoptosis in response to chemotherapy Here, we studied both Fas antigen expression on leukemic cells and its clinical significance in newly diagnosed acute myelogenous leukemia(AML).
To evaluate the relative clinical significance of Fas and Bcl-2 expression, we also investigated the expression of Fas and Bcl-2 antigen on CD34-positive AML cells.
Methods: We have analyzed the correlation of Fas and Bcl-2 expression with the clinicopathological parameters and therapeutic outcomes to the various chemotherapy in 37 patients with AML retrospectively. Expression of Fas and Bcl-2 antigen on the leukemic blasts was analyzed by flow cytometry direct immunofluorescence method.
Results: The number of Fas-positive cells in each sample was heterogeneous(range, 1.1% to 74.4%). Greater than 50% of the cells showed Bcl-2 staining in every samples,
and the percentage of cells coexpression Bcl-2 and CD34 antigen was
heterogeneous(range, 4.6% to 96.9%). There was no correlation between Fas and Bcl-2 expression in individual AML cells nor CD34-positive AML cells. Fas expression had
substantial effect on the remission rate : 84.2% in Fas-positive versus 44.4% in Fas-negative AML. Fas expression remained an independently significant predictor for
response to remission induction chemotherapy.
Conclusion: Although the mechanism by which induction chemotherapy can result in better therapeutic outcome in Fas-positive AML is to be addressed, we may suggest
that the quantification of Fas expression can be predictive of treatment outcome in AML. Further studies for evaluation of the biologic and clinical characteristics of Fas
antigen and the mechanism of apoptosis in AML are warrented.

Keywords: Fas antigen, Bcl-2 antigen, Acute myelogenous leukemia