Objective:To study the effect of interleukin-18 on transdifferentiation in renal tubular epithelial cells(TECs).Methods:Human proximal tubular epithelial cell line(HK-2) was cultured in vitro.TECs were exposed to different concentrations(0,0.1,1,10 and 100 ng/ml) of IL-18 for 24,48 and 72 hours.At the end of each incubation,the expressions of the ?-SMA and TGF-?_1 mRNA were assessed by RT-PCR,the rate of ?-SMA expressing TECs was assessed by immunocytochemistry,and the expression of the ?-SMA protein was assessed by Western blotting.Results:(1)The expressions of ?-SMA and TGF-?_1 mRNA were increased significantly by a dose- and time-dependent manner when TECs were exposed to IL-18(P