This Figure shows a schematic of the experimental method for attempting to measure cholesterol efflux capacity from human serum. In this novel in vitro system, J774 macrophage cells were cultivated in a dish with an acyl CoA:cholesterol acyltransferase (ACAT) inhibitor to prevent cholesterol esterification. The cultivated macrophage cells were then treated with cyclic AMP to up-regulate ABCA1 expression (see first Figure). Then human serum was depleted of apoB-containing (low-density) lipoproteins using polyethylene glycol (PEG) precipitation, and the supernatant, which contained the residual HDL cholesterol, was applied to the macrophage cells, which had been labeled with tritiated cholesterol.
The result of this procedure was a number that gives us the percent free cholesterol efflux over this 4-hour incubation period, and this serves as a measure of how capable this serum-extracted HDL cholesterol was for promoting cholesterol efflux from these macrophage cells – ie, a readout of the capacity of that person’s HDL to promote cholesterol efflux.
J Clin Lipidol. 2011; 5(6).