LCAT(Phosphatidylcholine-sterol acyltransferase) is an enzyme in the extracellular metabolism of plasma lipoproteins, which converts cholesterol and phosphatidylcholines(lecithins) to cholesteryl esters and lysophosphatidylcholines. It is reported that Apolipoprotein E (apoE) is the main LCAT activator in glia- conditioned media (GCM). Thus, a binding ELISA assay was conducted to detect the association of recombinant human LCAT with recombinant human apoE. Briefly, recombinant human LCAT were diluted serially in PBS with 0.01% BSA(pH 7.4). Duplicate samples of 100ul were then transferred to apoE-coated microtiter wells and incubated for 2h at 37°C. Wells were washed with PBST and incubated for 1 h with anti-LCAT pAb, then aspirated and washed 3 times. After incubation with HRP labelled secondary antibody, wells were aspirated and washed 3 times. With the addition of substrate solution, wells were incubated 15-25 minutes at 37°C. Finally, add 50µL stop solution to the wells and read at 450nm immediately. The binding activity of LCAT with apoE was shown in Figure 1 ,the EC50 for this effect is 0.036ug/mL.