Influence of Radix Isatidis on the endotoxin-induced release of TNF-alpha and IL-8 from HL-60 cells. 
The effects of active antiendotoxin chemical fraction isolated from Radix Isatidis (fraction D) on TNF-alpha and IL-8 secretion in HL-60 cells induced by lipopolysaccharide (LPS) were studied.  The appropriate densities of cell suspension and fraction D solution were determined by MTT colorimetric method.  Fraction D and LPS were added to HL-60 cell suspension with three different methods respectively.  The contents of TNF-alpha and IL-8 in the cultured supernatant induced by LPS were detected by using ELISA method.  The results showed that the absorbance (A) was directly proportional to the number of cells and the linearity was good in the range from 0.25 x 10(5) to 2 x 10(5) cell/mL cell suspension.  The fraction D significantly inhibited the oversecretion of TNF-alpha and IL-8 in HL-60 cells induced by LPS at the concentration of 7.812 mg/mL which had no cytotoxicity.  It was indicated that the antiendotoxin mechanism of the active fraction from Radix Isatidis was contributed to the inhibition of the oversecretion of cytokines induced by LPS.