Abstract： Objective To detect the expression of cytokines by acute promyelocytic leukemia (APL) cells before and after exposure to arsenic trioxide. Methods Diagnoses were performed according to the FAB cytological classification criteria and cytogenetic criteria. Bone marrow or blood samples from APL patients were collected in heparinized tubes,then primary APL cells were separated by traditional Ficoll-Hypaque density centrifugation and purified after adherence to plastic surfaces. IL-1β, IL-6, IL-8, TNFα and G-CSF levels in the leukemia cell culture supernatants were detected by ELISA. At the same time, nitro blue tetrazolium (NBT) reduction test was used to detect the differentiation of APL cells. Results After 96 hours exposure to arsenic trioxide, 10-6 mol/L in vitro or 10 mg/d in vivo, APL cells showed a significant increase of IL-1β(P<0.05) and G-CSF(P<0.05) production, and a significant decrease of IL-6 (P<0.05) and IL-8 (P<0.05). However, there was no obvious variation of TNFα when compared with APL cells without exposure to arsenic trioxide. On the other hand, the proliferation ratio of APL cells in vitro was statistically correlated to the IL-1β secretion ratio or G-CSF secretion ratio. The cell number ratio in patients with detectable IL-1β or G-CSF was higher than that without detectable IL-1β or G-CSF.Conclusion IL-1β and G-CSF secretion may play an important role in the proliferation of APL cells after exposure to arsenic trioxide.