Fig. 8. Effect of specific SR-BI/BII blocking antibody on native or tyrosylated oregon-HDL₃ cell association (A) and cholesterol ether-HDL₃ uptake (B). J774-A1 cells were cholesterol loaded with AcLDL (50 µg apo B/ml) as described in Materials and Methods. After an 18 hour equilibration period, the cells were incubated for 3 hours at 37°C with 10 µg/ml of native (black) or tyrosylated (grey) Oregon-HDL₃ (A) or [³H]cholesteryl hexadecyl ether-HDL₃ (B) with or without 0.6 mg/ml of blocking rabbit SR-BI/BII antibody (preincubated for 30 minutes with cells before the addition of HDL₃, in a final volume of 0.2 ml). Control experiments were carried out with 0.6 mg/ml of rabbit IgG in the same conditions. After extensive cell washing, the specific cell-associated fluorescence and cellular [³H]cholesteryl hexadecyl ether uptake were determined by flow cytometry and radioactivity measurement, respectively. Results were expressed as a percentage of the value without antibody or rabbit IgG. Each value is the mean±s.e.m. of three independent experiments using different lipoprotein preparations.