A two-step procedure for obtaining normal peripheral blood T-lymphocytes using continuous equilibrium density gradient centrifugation on percoll

Red cell dimorphism in a young man with a constitutional chromosomal translocation t(11;22)(p15.5;q11.21)

A constitutional, balanced chromosomal translocation t(11;22)(p15.5;q11.21) was discovered in a tall young man during investigation of a red cell dimorphism. The red cells are predominantly normochromic and normocytic with a small population of hypochromic, microcytic cells. Contained within the regions involved in the translocation are determinants of height (IGF2:11p15.5), red cell haemoglobinization (non-alpha globin gene complex: 11p15.5) and oncogenesis (cHa-Ras-1, Beckwith-Wiedemann syndrome: 11p15.5; BCR, Burkitts lymphoma, Ewings sarcoma: 22q11.21). To map these regions in the patient, somatic cell hybrids were generated and cell lines that segregated the chromosomes 11, 22 and 22q- were obtained. All 11p15.5 sequences investigated, in particular the whole of the non-alpha globin gene complex including its 5' and 3' regulatory sequences, were found to be translocated to 22q-. All chromosome 22 sequences studied were missing from the 22q- cell lines, including the proximal anonymous marker D22S24, and therefore assumed to be translocated to 11p+. These results suggest that the non-alpha globin gene complex has been moved close to the centromeric region of chromosome 22q-. It is postulated that such a positioning subjects the complex to a variegated position-effect bringing about a clonal exclusion of the complex and thus producing a beta-thalassaemia trait mosaic.

Uptake and intracellular distribution of iron from transferrin and chelators in erythroid cells

Iron chelators of different physicochemical properties were studied for their ability to donate iron in vitro to uninduced K562 cells, human bone marrow cells and purified human erythroblasts. To a large extent uptake was found to be related to lipophilicity and those chelators able to deliver iron to the cells in significant amounts were also able to deliver iron to ferritin and haem. Some differences in the distribution of iron delivered was observed but no chelator showed exclusive delivery to or rejection of a particular cellular iron compartment. Several chelators could probably substitute for transferrin and be used to probe metabolic events subsequent to iron removal from transferrin. Two chelators which were excellent iron donors were also found to cause considerable inhibition of iron incorporation into haem from transferrin. The implications of this for in vivo toxicity are briefly discussed.

Effect of phytohaemagglutinin on the synthesis and secretion of ferritin in peripheral blood lymphocytes

Stimulation of lymphocytes with phytohaemagglutinin (PHA) causes an increase in the rate of ferritin and total protein synthesis which is not enhanced by supplementing the medium with iron. There is an increase in intracellular ferritin content which is amplified by the presence of iron but this is also observed in the absence of PHA stimulation. The increased cellular ferritin is greater for heart type ferritin than for spleen type ferritin. Ferritin secreted into the medium from the cells shows a relative preponderance of spleen type ferritin compared to the intracellular protein. The data shows a dissociation between ferritin synthesis, cellular accumulation and secretion for which the mechanisms have still to be elucidated.

Ferritin-bearing T-lymphocytes and serum ferritin in patients with breast cancer

Flow cytometric studies of T-lymphocytes in breast cancer patients show that the number of cells bearing ferritin on their surface is significantly greater than normal. The number of ferritin-bearing T-cells does not appear to be related to the clinical stage of the disease nor to the serum ferritin concentration, though this is higher in cancer patients than in normal women. There is no difference in the number of T-cells positive for interleukin 2 or transferrin receptors nor in the absolute number of T-cells, T-helper cells and B-cells between normal women and those with breast cancer or benign breast disease. However, there is a significant increase in the level of HLA DR-positive T-cells and T-suppressor cells in breast cancer patients. While the significance of ferritin-bearing T-cells is not known an increase in their number appears to be associated with cancer.

Measurement of 5-aminolevulinic acid synthase activity in whole and fractionated human bone marrow: effect of myeloid cell lysis by monoclonal antibody

A sensitive radiochemical assay for the measurement of bone marrow and erythroblast 5-aminolevulinic acid (ALA) synthase (EC 2.3.1.37) was developed and optimized with respect to sample preparation and reagent concentration. Succinylacetone (4,6-dioxoheptanoic acid) was used to prevent ALA utilization during the incubation period. Sample purification on a Sep-Pak cartridge (Waters Associates) followed by reverse-phase high-performance liquid chromatography (HPLC) allowed rapid isolation of pure ALA-pyrrole, free from radioactive succinate and other contaminants. ALA synthase activity was measured in unfractionated bone marrow and in samples from which myeloid cells had been removed by monoclonal antibody-mediated cell lysis. Myeloid-derived ALA synthase was calculated and found to contribute approximately half of the total unfractionated marrow enzyme activity. This suggests that results from previous studies using unfractionated bone marrow which have assumed that myeloid cells are an insignificant source of ALA synthase require reappraisal.

Separation of malignant plasma cells from the bone marrow of patients with myelomatosis

Complement-mediated lysis of bone marrow cells from patients with myelomatosis using a rabbit antiserum raised against normal peripheral blood mononuclear cells was found to greatly enrich the abnormal plasma cells. Cellular morphology was good and the cells were able to synthesize and secrete paraprotein. This was found to be a quick and useful method of preparing myeloma plasma cells for further studies of their metabolic properties.

Isoferritins in normal leucocytes

Monocytes, lymphocytes and polymorphs were separated from the peripheral blood of normal human subjects. Ferritin concentrations were determined with antibodies to both human spleen and heart ferritins. The heart type ferritin concentration in monocytes was 38.4 +/- 21.6 fg/cell (mean +/- SD), in lymphocytes 8.6 +/- 6.6 fg/cell and in polymorphs 3.2 +/- 2.4 fg/cell. Spleen type ferritin concentrations (fg/cell) were 15.6 +/- 7.0 in monocytes, 6.6 +/- 5.7 in lymphocytes and 7.0 +/- 4.6 in polymorphs. The mean heart/spleen ferritin ratios were 2.8/1 for monocytes, 2.0/1 for lymphocytes and 0.6/1 for polymorphs. The cell extracts were also subjected to anion exchange chromatography. Heart type ferritin eluted at a higher chloride ion concentration than spleen type ferritin. Both H and L subunits were synthesized by mononuclear cells when incubated with 3H-leucine. Human leucocytes contain a wide range of isoferritins and ferritin concentrations may be considerably underestimated in conventional assays for serum ferritin which employ antibodies to liver or spleen ferritin.

Globin chain synthesis ratios in sideroblastic anaemia

Globin synthesis ratios were measured on reticulocytes from nine patients with primary acquired sideroblastic anaemia (SA), four patients with hereditary or congenital SA, two patients with secondary acquired SA and three patients with iron deficiency (ID). Ten of the samples from patients with SA and all the samples from patients with ID had normal ratios. Samples from three patients had significantly abnormal ratios, one from a patient with SA and acquired Hb H disease (alpha/beta 0 X 26), one from a patient with secondary acquired SA (alpha/beta 0 X 88), and one from a patient who went on to develop acute myeloblastic leukaemia (alpha/beta 1 X 36). Globin synthesis was stimulated by 100 microM haem similarly in normal, SA and ID reticulocytes. Any limitation of globin synthesis in SA and ID is therefore not easily reversible by adding haem. Inhibition of haem synthesis in nonsideroblastic reticulocytes using 4 mM isonicotinic acid hydrazide for 1 h incubation affected neither total globin synthesis nor the alpha/beta ratio. These results contradict the view that decreased haem synthesis decreases globin chain synthesis and decreases the alpha/beta globin chain synthesis ratios in human reticulocytes. Previously reported findings that haem could reverse globin chain synthesis inhibition in SA were good evidence for a primary deficiency of haem synthesis in the erythroblasts of these patients. Our inability to substantiate these findings emphasizes the need for a re-evaluation of the aetiology of sideroblastic anaemia.

Enrichment of erythroblasts from human bone marrow using complement-mediated lysis: measurement of ferritin

Sequential lysis of human bone marrow cells with a monoclonal antibody directed against myeloid cells (TG1) and a rabbit antiserum raised against peripheral blood mononuclear cells gave preparations in which 78-97% of the nucleated cells were erythroid, with a 24-77% recovery. Viability was high, morphology was good and the cells were able to divide and differentiate in culture. No metabolic experiments were carried out but the ferritin content of the erythroblasts was measured in four experiments and found to be about 200-2000 times higher than that found in normal erythrocytes. The H/S ratio was high in both erythroblasts and erythrocytes. Fractionation on the basis of density of two erythroblast preparations, one from a patient with sideroblastic anaemia and one from a patient with megaloblastic anaemia, showed that the most immature erythroblasts contained the highest content of ferritin and that this fell with maturation. The H/S ratio stayed the same or fell with maturation. It was concluded that this method would be valuable for the study of the role of erythroblast ferritin in normal and pathological situations.