Decrease of cholesterol concentration in human erythrocyte ghosts in old age.

The lipid composition of the erythrocyte membrane ghosts of 95 relatively healthy elderly subjects was compared between four age groups: 70 to below 75 years (I), 75 to below 80 (II), 80 to below 85 (III) and 85 to below 90 years of age (IV). The molar ratio of phospholipid to cholesterol (PL/CH) in the erythrocyte ghosts increased with advancing age. Whilst PL levels did not change significantly, a decrease of membrane cholesterol was found. Therefore, the red cell membrane cholesterol seems to parallel the well-known pattern of variation of mean plasma total cholesterol and LDL cholesterol concentrations with age: an increase to a maximum in the sixth decade of life, and a decline thereafter. The processes which are responsible for these changes in cholesterol level with age have not been delineated. However, the findings suggest that one might get different results in studies of age-dependent membrane lipid alterations if rough age group divisions are made (below 30 years of age vs. over 70 years) or to subdivide the group of the elderly.