To investigate the effects of granulocyte macrophage colony stimulating factor (GM-CSF) which was secreted from the fresh leukemic cells of patients with acute myeloid leukemia (AML) and recombinant human GM-CSF(rhGM-CSF) on the apoptosis of the primary incubative AML cells,the level of GM-CSF was measured by means of radioimmunoassay,the DNA ladder was detected by using DNA electrophoresis,and the percentage of apoptotic cells,percentage of expression and the mean fluorescence intensity(MFI) of bcl-2 were respectively assayed by means of flow cytomtric analysis.After the fresh leukemic cells from 5 cases were incubated for 24 hours,GM-CSF in 3 of 5 cases were seen,their percentage of apoptotic cells was less than the other 2 cases,and the MFI of bcl-2 in the 3 of 5 cases was obviously enhanced.After the fresh leukemic cells were treated with cytarabine (Ara-C) 5?g/ml in combination with rhGM-CSF 5?g/ml for 24 hours,the percentage of apoptotic cells was more than the cells treated with Ara-C alone and it upward to (56 4?7 4)%(p