Objective To study the mechanism of Liangxue Jiedu Decoction for acute aplastic anemia.Methods Enzymelinked immunosorbent assay was used to detect TNF-α

IFN-γ and sIL-2R in myeloid supernatant of acute aplastic anemia patients and normal controllers.Modulation of Liangxue Jiedu Decoction on myelomonocytic TNF-α

IFN-γ and sIL-2R induced by plant hemagglutinin was observed in vitro test.Results TNF-α

IFN-γ and sIL-2R in myeloid supernatant of acute aplastic anemia patients were higher than those of normal controllers with significant differences（P<0.05）.Vitro test showed that Liangxue Jiedu Decoction inhibitted the secretion of IFN-γ and sIL-2R significantly（P<0.05 or P<0.01）

and had no effect on INF-α（P>0.05）.Conclusion The pathogenesis of acute aplastic anemia is relevant to abnormal increasing of TNF-α

IFN-γ and sIL-2R.Liangxue Jiedu Decoction can cool the blood

stanch bleeding

clear heat and resolve toxin to cure acute aplastic anemia

which may be concerned with its decreasing IFN-γ and sIL-2R and improving haematopoiesis as well.