Red cell destruction by human monocytes--changes in intracellular ferritin concentration and phenotype.

Mononuclear cells from 5 normal men and 5 patients homozygous for hereditary haemochromatosis (HFE) have been incubated for 18 h with or without the addition of sheep red blood cells coated with antibody (SRBC). In the absence of SRBC mean H type ferritin concentrations were greater than L type (normals: mean L type 11.6 ng/10(6) cells, H type 15.5; patients, L type 23.5 ng/10(6) cells, H type 41.6). In the presence of SRBC, monocyte L type ferritin concentrations increased considerably (76 ng/10(6) cells in normals and 141 ng/10(6) cells in patients) but H type ferritin concentrations were the same or decreased compared with incubation in medium only. Incubation with additional iron (ferric ammonium citrate, 2.5 micrograms Fe/ml) increased both H and L type ferritin concentrations. Erythrophagocytosis thus appears to cause differential regulation of H and L ferritin subunit synthesis or breakdown. Normal subjects and patients do not differ in this response to erythrophagocytosis.