Iron forms in the cytosol of healthy volunteer monocytes (□) and HH 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 removed by centrifugation. Cytosol samples were frozen, dried, reconstituted with bidistilled deionized water, filtered, and fractionated on SE-HPLC. Radioactive iron was measured again in the eluted fractions. Iron was recovered as Hb, LMW-Fe, and ferritin. The results are expressed as percentage (mean ± SD) of the total iron present in the system (= cells + supernatant) of five experiments. Statistical analysis was by Student's t-test. Results of controls and patients were not statistically different.