Quantitation and localization of erythrocyte cholesterol in wild-type and mutant mice.

The cholesterol content of erythrocytes from wild-type, reticulocyte-enriched wild-type, apoE^−/−, SR-BI^−/−, andSR-BI^−/−/apoE^−/−mice was examined by 2 methods. First, cells were incubated with filipin, to allow fluorescent detection of cholesterol by flow cytometry (panel A) and confocal microscopy (panel C). (Note that in panel A the y-axis is logarithmic.) Second, cholesterol in erythrocyte lysates was measured directly by a biochemical method (panel B). The boxes show the range for 80% of the data points; the lines within the boxes show the median values; and the bars show outlying data points (if any). At the bottom of the plot, − indicates normal mouse chow diet, and + indicates 3 months on the high-cholesterol diet.