Erythroblast ferritin (EF), isolated from phenylhydrazine-anemic rabbit marrow, interacts with components of normal plasma and forms a complex separable by starch granule electrophoresis and by dialysis techniques. The binding is facilitated at low ionic strength. The plasma factors responsible for binding EF are present in autologous, as well as homologous, plasma of normal nonimmune rabbits, although binding activities are quite variable in different plasmas. The binding activity for rabbit EF is also present in heterologous plasma of mouse, guinea pig, and man. The active principles in plasma were identified as two heat-stable components which fractionate as immunoglobulins, one as IgG and the other as IgM. The results support the hypothesis that natural antiferritin antibodies of low titer are present in normal plasma.
The metabolism of purified * 51-labelled homologous transferrin in rabbits with haemolytic anaemia was compared to that in control rabbits and no significant differences were found. During 3 weeks of haemolysis plasma transferrin concentrations did not change appreciably. The fractional turnover rate was 43 % of the intravascular pool per day. The intravascular pool was 45% of the total exchangeable transferrin.
Serum ferritin levels in a patient with HEMPAS syndrome (hereditary erythroblastic multinuclearity associated with positive acidified serum test) were correlated with body iron stores directly measured on spleen and liver biopsy specimens as well as by quantitative serial phlebotomy. Normal serum ferritin concentrations were found in the presence of a moderate excess in iron stores (approximately 6-12 times normal). They temporarily increased after transfusion and splenectomy with a prompt return to the normal range. As repeated phlebotomies over a period of nine months depleted the excess iron stores, the serum ferritin ultimately decreased to a subnormal concentration. The serum ferritin concentration was not a reliable index of increased body iron stores in this iron overloaded patient, but did reflect their depletion by serial phlebotomy.
The contribution of the high molecular weight hemoglobin (HMW Hb) to the antisickling effect produced by treatment of sickle cell erythrocytes with methyl acetimidate (MAI) was investigated. Erythrocytes obtained from sickle cell anemia and normal individuals were incubated with varying concentrations of MAI. The presence of intermolecularly crosslinked HMW Hb was detected by gel filtration of dialyzed hemolysates obtained from the incubated cells. HMW Hb has an increased oxygen affinity and a decreased Hill constant. Intermolecular crosslinking per se was shown to have no additional effect on Hb oxygen affinity other than that due to Hb amino group modification. Modified deoxy Hb S of normal molecular weight has a higher minimum gel concentration (MGC) than control deoxy Hb S. Deoxy HMW Hb did not gel at intracellular Hb concentrations. Therefore, the intracellular concentration of deoxy Hb S that gels necessarily decreases as the HMW Hb concentration increases. This "excluded volume effect" of the non-gelling Hb would be expected to increase the MGC of completely deoxygenated hemolysate obtained from the treated cells. The HMW Hb contributes to the inhibition of sickling resulting from treatment of sickle erythrocyte with MAI by increasing both MGC and oxygen affinity of the modified Hb.
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