Distribution of iron inside healthy volunteer (A) and HH (B) monocytes after erythrophagocytosis and during the release experiment. At different time points during iron release, monocytes were lysed by freeze-thawing, and cell membranes and nuclei were removed by centrifugation. Radioactivity was measured in the pellet-membrane fraction (•) and in the supernatant-cytosol fraction (▪). The total radioactivity present in the cell at any given time is also shown (▾ and dashed line). Results are expressed as percentage (mean ± SD) of total iron present in the system (= cells + supernatant) of five control and six HH experiments.