Aim To further discuss the anti-atherosclerotic mechanism of adiponectin,the impact of adiponectin on cholesterol efflux mediated by ATP binding cassette transporter A1(ABCA1) in THP-1 derived foam cells was studied.Methods THP-1 derived foam cells were incubated with apolipoprotein A1(apoA1),adiponectin,and apoA1+adiponectin in vitro,respectively.RT-PCR,ELISA and HPLC were used to determine the influence of adiponectin on ABCA1 mRNA and protein expression and on intracellular cholesterol content before and after treatments.Results Adiponectin could up-regulate ABCA1 mRNA and protein expression in THP-1 derived foam cells in vitro.Adiponectin alone could enhance the transformation from cholesterol ester to free cholesterol.In combination with apoA1,it could increase the ABCA1 mediated efflux of intracellular cholesterol significantly.Conclusions Adiponectin inhibit intracellular cholesterol deposit in foam cells by enhancing the hydrolysis of intracellular cholesterol ester.It can up-regulate ABCA1 expression,and accelerate ABCA1 mediated intracellular free cholesterol efflux.