Accumulation and release of isoferritins during incubation in vitro of human peripheral blood mononuclear cells.

Ferritin concentration has been measured in peripheral blood mononuclear cells and in the incubation medium following in vitro culture. Antibodies to both heart and spleen ferritin were used. Mononuclear cells cultured in medium containing about 12 mumol Fe/l accumulate ferritin rapidly with an increase in the heart:spleen ferritin ratio from 3:1 to about 10:1. Higher concentrations of iron (100 mumol/l) produce an even greater effect. The accumulation of ferritin is prevented by the addition of desferrioxamine (2 mmol/l) to the incubation medium. Accumulation of ferritin appears to take place largely in monocytes. Phagocytosis of red blood cells also causes rapid accumulation of ferritin but without any change in the heart:spleen ratio. Small amounts of both spleen and heart type ferritin are released during incubation in an iron containing medium and following phagocytosis of red blood cells. Some concanavalin A binding ferritin is also released suggesting that phagocytic cells may be a source of the concanavalin A binding ferritin found in normal plasma.