Differences in intramembrane particle distribution in young and old human erythrocytes.

The distribution of intramembrane particles in human erythrocytes was studied by freeze-fracture on young and old cells and compared to that obtained after ATP depletion or following addition of a clustering agent. It was shown that intramembrane particles became aggregated and the mean particle density increased as the cells aged. Likewise, both particle aggregation and increased density were found in young cells after moderate ATP depletion.