Ferritin concentration in normal and abnormal erythrocytes measured by immunoradiometric assay with antibodies to heart and spleen ferritin and Mössbauer spectroscopy.

Immunoradiometric assays using antibodies to spleen and heart ferritin were combined with Mössbauer studies on normal and pathological erythrocytes. All erythrocytes examined were found to contain greater amounts of heart type than spleen type ferritin. The ferritin concentration in erythrocytes from patients with beta thalassaemia, sickle cell disease and sideroblastic anaemia is much higher than in normal cells. When the concentration of ferritin-like iron in the pathological erythrocytes measured by Mössbauer spectroscopy is compared to the total amount of ferritin assayed by the two antibodies in the same haemolysates the iron/protein ratio ranges between 0.3 and 3.4. The iron/protein ratio in iron-filled ferritin molecules is about 0.56 and values in excess of this suggest that the iron detected in these cells is a mixture of ferritin molecules, partly denatured ferritin polymers and 'haemosiderin'. There is a possibility that erythrocytes contain an immunologically distinct type of ferritin that is not detected by existing assays, but we have no direct evidence for this.