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A 5½-yr-old child developed severe anemia with erythroid hypoplasia and 50% ringed sideroblasts in his bone marrow. A serum inhibitor of erythropoiesis was demonstrated, utilizing syngeneic and autologous bone marrow in a plasma-clot culture system. The IgG fraction of the patient’s serum effected similar suppression of erythroid colony formation. Prednisone therapy was ineffective, but following treatment with cyclophosphamide, normal erythropoiesis was established, ringed sideroblasts disappeared, and his serum no longer inhibited erythropoiesis in vitro. Cyclophosphamide was discontinued, and the patient has remained hematologically normal. This patient is an example of antibody-mediated sideroblastic anemia successfully treated with a cytotoxic drug.

In order to study developmental aspects of splenic function and dysfunction in children with Hb SS disease and other Hb S syndromes, red cells were examined by interference phase–contrast microscopy. In the youngest children studied (<1 yr) the number of red blood cells bearing “pocks” was low (<1 %), the same as in normal eusplenic controls. In most children over 8 yr of age, >12% of the red blood cells were pocked, in similarity to what is observed in surgically asplenic individuals. Between 1 and 8 yr of age, many Hb SS children had intermediate numbers of pocked red blood cells, and that suggested hyposplenism. Young children with Hb AS, S-βthalassemia, and S-HPFH were found to have normal splenic function by this technique. Children with Hb SC disease had a moderate degree of splenic dysfunction. This technique correlates with Howell-Jolly body enumeration and 99mTc spleen scans, but it is semiquantitative, and it appears to differentiate the transfusion-reversible “functional” hyposplenism of childhood and the anatomic asplenia secondary to autosplenectomy of later life. Interference phase microscopic enumeration of red cell pocks is a useful and accurate way to assess the onset of splenic dysfunction, which identifies the time of increased susceptibility to overwhelming bacterial infections.

Fibrinogen Ledyard was discovered in a 10-year-old boy with a mild bleeding history. His father had the same defect and a bleeding history after surgery. Both patients were heterozygous. The plasma fibrinogen concentration was normal immunologically (335 mg/dL) and very low functionally (52 mg/ dL). Purified fibrinogen Ledyard had a prolonged polymerization, which was somewhat corrected by addition of Ca2+ions. High performance liquid chromatography (HPLC) analyses of the f ibrinopeptides released by thrombin showed 1 mol of fibrinopeptide A (FPA) and 2 mol of fibrinopeptide B (FPB) released per mole of fibrinogen Ledyard. Steady-state kinetic parameters were evaluated for release of FPA by thrombin. When the concentration of fibrinogen Ledyard was corrected to 50% of total protein, because only 50% of fibrinogen Ledyard can release FPA, the kinetic constants were similar to those of control fibrinogen (Km= 7.5 μmol/L for Aα chain, kcat= 54 s-1). This finding indicates that the cleavage site of the Aα chain in these abnormal molecules may not interact with the catalytic site of thrombin. The three chains of fibrinogen Ledyard were isolated on reverse-phase C4-HPLC. The sequence of the amino terminus of Aα chain showed that Arg in position 16 was replaced by Cys in the abnormal molecules. Approximately half of fibrinogen Ledyard (52%) was clotted by reptilase, suggesting that fibrinogen Ledyard may consist of 50% normal homodimers (AαArg16• AαArg16) and 50% abnormal homodimers (AαCys16• AaCys16). Abnormal molecules could form disulfide bond between the AαCys16residues. Thus, the abnormal molecules have a different structure that does not bind to thrombin. Probably the abnormality of polymerization of fibrinogen Ledyard results from the interaction of the abnormal molecules with normal fibrin monomers, so that the growth of fibrin protofibrils is inhibited. This abnormal fibrinogen supports adenosine diphosphate-inducβd platelet aggregation in a normal manner.