Identification and quantitation of embryonic and three types of fetal hemoglobin produced on induction of the human pluripotent leukemia cell line K-562 with hemin

Reactivation of Fetal Hemoglobin for Treating β-Thalassemia and Sickle Cell Disease

Reactivation of fetal hemoglobin (HbF) in adult hematopoietic cells has the potential for great clinical benefit in patients bearing deleterious mutations in the β-globin gene, such as β-thalassemia and sickle cell disease (SCD), since increasing the production of HbF can compensate for underproduction of β-globin chains (in β-thalassemia) and it can also disrupt sickle hemoglobin polymerization (in SCD). Thus for the past few decades, concerted efforts have been made to identify an effective way to induce the synthesis of HbF in adult erythroid cells for potential therapeutic relief from the effects of these β-globinopathies. Chemical inducers of HbF as well as a number of transcription factors that are able to reactivate HbF synthesis in vitro and in vivo in adult erythroid cells have been identified. However, there has been only limited success in attempts to manipulate either the drugs or regulatory proteins, and in only a fraction of patients, and there is wide variation in individual response to these drugs or transcription factors. These studies highlight the importance for understanding the molecular mechanisms underlying hemoglobin switching so that future studies can be designed to treat these disorders.

The structure and function of normal and abnormal haemoglobins

This chapter reviews general aspects of the normal human haemoglobins which include those predominantly present in the embryo, the fetus and newborn baby, and in the normal adult. Special emphasis is given to factors which affect the levels of fetal haemoglobin in the adult because increased percentages of Hb F can be of great benefit to adults with certain haemoglobinopathies such as sickle cell anaemia and beta-thalassaemia. A review of the numerous Hb variants published since the discovery of Hb S in 1959 reveals a steady stream of newly detected abnormalities; most of these are the result of single-point mutations in the alpha-, beta-, gamma-, or delta-globin genes. Of the more than 600 variants listed in a repository, some 200 have clinical significance because of a decreased stability, a change in functional properties, among others. Methodology developed for the detection and quantitation of normal and abnormal Hb components has been greatly modified during the past 30 years; isoelectrofocusing and different fast developing micro chromatographic procedures are the methods of choice. Analyses of DNA isolated from the white cells has become most useful for the final characterization of the variants; this methodology consists of amplification of a desired segment of DNA and identification of a mutation with labelled oligonucleotide probes. Additional methods include sequence determination of this amplified DNA and identification of known mutations with an allele specific amplification procedure.

K562 cells: a source for embryonic globin chains

A combination of DEAE-cellulose chromatography and reversed-phase high-performance liquid chromatography (HPLC) has been used to devise a method for generating large quantities of embryonic as well as fetal globin chains. The identity of these globin chains was further confirmed by their tryptic peptide mapping. This technique could, therefore, provide a reliable source for these polypeptides for both analytical and immunological purposes. Moreover, the study of human hemoglobin switching, particularly embryonic to fetal, has been greatly hampered by the absence of a suitable model. K562 cells, due to their potential for differential induction of embryonic and fetal hemoglobin synthesis, can thus be used for this purpose and the various hemoglobins produced can then be effectively monitored using this method.

Evidence for the synthesis of embryonic globin chains in adult erythroid progenitor cells

Embryonic globin chains were found to be synthesized in vitro by the BFU-E colonies derived from adult sickle cell anemia (SS) patients, their heterozygous relatives as well as a few normal controls. In the absence of sufficient material for conducting direct structural analyses of these peptides, they were confirmed by evaluating the co-migration of the epsilon and zeta-chains with the corresponding structurally characterized globin chains obtained from K562 cell lysates on a reversed phase high performance liquid chromatogram. The presence of zeta-chain was also confirmed using an immunologic procedure. Furthermore, significant 35S-methionine incorporation peak was observed corresponding to the zeta-chain synthesized by the BFU-E-derived colonies implying an active synthesis of this embryonic globin chain in BFU-E cells obtained from hemopoietically adult persons.

The types of hemoglobins and globin chains in hydrops fetalis

Details are presented of analyses of hemoglobins in blood samples from four newborn babies with hydrops fetalis using reversed phase and anion exchange high performance liquid chromatographic methodology. Three were homozygous for the alpha-thalassemia-1 (SEA) deletion, and one was a compound heterozygote for the same deletion and the larger alpha-thalassemia-1 (Fil) deletion. All four babies had beta, G gamma, A gamma, and zeta chains; these chains were present in Hb Bart's or gamma 4, Hb Portland-I (zeta 2 gamma 2), and Hb Portland-II (zeta 2 beta 2). Hb H (beta 4) could not be detected. The level of zeta was directly related to the level of beta and, thus, the fetal age. A lower level of zeta chain was present in the baby with the compound heterozygosity because the large deletion (Fil) on one chromosome included the zeta and psi zeta genes. Circulating red cells, i.e. reticulocytes and nucleated red cells, were unable to synthesize zeta chains, indicating that this capability must have ceased a few months prior to birth. Quantitative data obtained by chromatographic procedures were greatly influenced by the condition of the blood sample and the way it was stored. Hb Portland-II (zeta 2 beta 2) and Hb Bart's (gamma 4) are rather unstable when a red cell lysate is stored at 4 degrees C; this is in contrast to Hb Portland-I (zeta 2 gamma 2) which appears to be stable. Samples can be stored as washed red cells or red cell lysates at -70 degrees C.

Detection of the embryonic zeta chain in blood from newborn babies by reversed-phase high-performance liquid chromatography

Reversed-phase high-performance liquid chromatography (RP-HPLC) using the large-pore Vydac C4 column has been used to detect and quantitate the embryonic zeta chain in blood samples of normal babies and of newborns with varying degrees of alpha chain deficiencies. The zeta chain eluted at the end of the chromatogram at about 130 min using a modified and extended gradient. Its identity was confirmed by structural analysis of zeta chain isolated from a blood sample of a fetus without active alpha globin genes, i.e. with hydrops fetalis (--/--). The quantity of zeta in normal babies is less than 0.7% [% of (alpha + zeta)] and is dependent upon the maturity of the baby as it was only present in babies with low levels of beta chain or hemoglobin (Hb) A. The presence of a zeta globin gene deletion [A. E. Felice et al., Hum. Genet., 73 (1986) 221; and P. Winichagoon et al., Nucleic Acids Res., 10 (1982) 5853] did not affect the level of zeta in the newborn. All babies with an alpha-thalassemia-2 heterozygosity, i.e. with three active alpha globin genes or -alpha/alpha alpha, had zeta in a range of 0.1-0.9%; again the level showed a negative correlation with that of the beta chain. Newborns with an alpha-thalassemia-2 homozygosity or -alpha/-alpha had a varying level of zeta of 0.3-2.3%, which did not correlate with the level of beta, suggesting that zeta chain production persists after birth in this condition. Macrochromatographic analyses in combination with RP-HPLC indicated that the zeta chain is present as zeta 2 gamma 2 or Hb Portland-I, as expected.

Continuous or modulation expression of hematopoietic cell antigens in sublines of the leukemia cell line, K-562

K-562 is described as a pluripotent leukemic cell line which expresses a diversity of hematopoietic cell differentiation antigens. With the use of monoclonal antibodies (MoAb), we show that the expression of these antigens is either "modulated", i.e. they are not expressed in early logarithmic growth but are expressed in late logarithmic growth, or "continuous", i.e. they are not affected by proliferation and phase of culture growth. Whether an antigen is modulated or continuously expressed appears to be an inherent property of the subline, since the expression of myeloid antigen binding the MoAb, PM81, was modulated on cells from a clone, whereas, the expression of this antigen was continuous by the parent subline and an independent subline F-1. Continuously expressed antigens appear to be an integral component of the K-562 cell surface matrix, while modulated antigen expression appears to be influenced by culture growth conditions.

Induction of differentiation in the human leukemia cell line SPI-802: morphological, immunological, and isoenzymatic changes

The phorbolester 12-0-tetradecanoylphorbol 13-acetate (TPA) was used for the induction of differentiation in cells of the human leukemia cell line SPI-802. The cellular morphology, surface marker antigen expression, and isoenzyme profiles of four enzymes (carboxylic esterase, acid phosphatase, hexosaminidase, and lactate dehydrogenase) served as parameters for monitoring the induced phenotypical changes. TPA led to distinct alterations of the morphology and significantly affected the growth rate with cessation of cell proliferation. No major increase in the number of nitro blue tetrazolium-positive cells or aggregation of cells, phagocytosis of latex beads, adherence to plastic surface, or development of pseudopodia were observed. As TPA-treated SPI-802 cells remained negative for these markers of the monocyte-macrophage complex, it can be concluded that the cells did not differentiate into monocytes and macrophages. The immunological marker profile based on testing of 55 monoclonal antibodies, terminal deoxynucleotidyl transferase and two erythrocyte rosette tests indicated a differentiation of SPI-802 cells along the granulocytic cell lineage. This was confirmed by isoenzyme analysis, especially that of carboxylic esterase. An isoenzyme specific for monocytes and macrophages was not detected. In earlier studies it was found that SPI-802 cells produce hemoglobin upon exposure to TPA or hemin. This latter observation and the present results suggested a comparison with the two erythroleukemia cell lines K-562 and HEL. SPI-802 cells appear to have the potential to differentiate along several cell lineages.

Erythroleukemia cell lines HEL and K-562: changes in isoenzyme profiles and morphology during induction of differentiation

The effects of the phorbol ester 12-O-tetradecanoylphorbol 13-acetate (TPA) and of hemin on the human erythroleukemia cell lines HEL and K-562 were studied using the parameters cellular morphology, cell proliferation, positivity in the nitro-blue tetrazolium (NBT)-reduction test, adherence to surface, development of pseudopodia, and isoenzyme profiles of carboxylic esterase, acid phosphatase, hexosaminidase and lactate dehydrogenase (LDH) separated by isoelectric focusing on horizontal polyacrylamide gels. TPA and hemin induced similar morphological changes in HEL and K-562, erythrocyte-like cells were seen to be the predominant population after exposure to hemin. Both TPA and hemin led to cessation of cell proliferation and to a dose-dependent decrease in the number of viable nucleated cells. Whereas HEL cells treated with TPA became positive in the NBT-reduction test, adhered to plastic surface and showed pseudopodia, HEL cells exposed to hemin and K-562 cells cultured with TPA or hemin did not show these markers indicative of the macrophage-cell lineage. TPA-treated HEL cells exhibited isoenzyme patterns which were characteristically seen in cells of the monocyte-macrophage complex. 'Myeloid isoenzyme profiles' were found in TPA-treated K-562 cells. As evidenced by the above described phenotypical changes, HEL cells appeared to differentiate along the macrophage and erythroid cell lineages. Induced K-562 cells displayed myeloid and erythrocytic markers.

K562 human leukemia cell passages differ in embryonic globin gene expression

K562 is a human leukemia cell line inducible by a variety of agents for the synthesis of embryonic and fetal hemoglobins. We compared early and late passages to determine whether a change has occurred in globin synthetic pattern. Clone LA4, derived from passage 199 which had been frozen by Lozzio in 1973, was compared with clone RA6, derived from a line received from Rutherford in 1979. Globin synthetic pattern was determined by incubation with [3]leucine, separation of globins by Triton-X100 polyacrylamide gel electrophoresis, and analysis by fluorography. For RA6, hemin-induced synthesis was greatest for zeta globin but minimal for epsilon globin, whereas for LA4 it was greatest for epsilon globin but minimal for zeta globin. Both lines are pseudotriploid with three No. 11 and three No. 16 chromosomes. However only RA6 has a translocation involving the short arm of chromosome 11 which contains the locus of the beta globin gene cluster. However, translocation-associated deletion does not simply explain the deficient inducibility of epsilon synthesis because G gamma and A gamma globins, whose genes are linked to the epsilon gene, are similarly inducible in the two lines.

Separation of zeta (zeta) and various gamma (gamma) chains of human embryonic hemoglobin Portland I by reverse-phase high-performance liquid chromatography

The zeta (zeta) and various gamma (gamma) chains of Hb Portland I have been separated and isolated from blood samples obtained from neonates with hydrops fetalis due to homozygous alpha-thalassemia. By using developers containing acetonitrile, methanol, and potassium phosphate and either an analytical (3.9 mm x 30 cm) or a preparative (7.8 mm x 30 cm) muBondapak C-18 column (Waters), globin chains from 200 micrograms to 5.0 mg have been isolated in pure forms. Analytical and preparative procedures using short (50-min duration) and extended (186-min duration) gradient programs have been developed. In addition to the type of column and developer conditions, the following factors are found to be important: (a) preparation of sample, (b) sample loading, and (c) cleaning of the column. Preliminary studies indicate that the yield ranges from 40 to 60% depending on the type of globin sample and the age of the column. This procedure also permits the separation of alpha, beta, and various gamma globin chains from fetal and adult samples.

Immunotherapy of human leukemia with antibody to pluripotential K-562 stem cells

Gamma (gamma) globulin was fractionated from the serum of a goat immunized with the pluripotential leukemia cell line K-562. The lyophilized gamma-globulin preparation, termed leukoglobulin, contained about 50% immune IgG and suppressed the proliferation of heterotransplanted leukemia and lymphoma cells of human origin. The main aims of this study were to evaluate the potential therapeutic value of leukoglobulin and to determine its toxicity in humans with terminal leukemia and patients whose disease was unresponsive to current therapy. Two patients with CML, one with AMML, four with ALL, and one with AML were treated once a week for up to 5 weeks with leukoglobulin intravenously at doses ranging from 2 to 29 mg/kg. Leukoglobulin was well tolerated with minimal adverse effects and produced an initial mobilization of blasts from the bone marrow, spleen, and other organs with a parallel increase in the number of blasts in the systemic circulation. Subsequent injections of leukoglobulin led to a sharp decrease and the eventual eradication of blasts from the peripheral blood and bone marrow. Except in patients with CML, immature cells other than blasts also markedly diminished. The results of the clinical trials indicated a synergism with or potentiation of most chemotherapeutic agents used. Two possible uses for a combination of leukoglobulin and antileukemic drugs are indicated by the results we report here; drug-antibody synergism for cases showing no response to chemotherapy alone or leukoglobulin given immediately after chemotherapy is administered to eliminate residual leukemia cells. Alternatively, leukoglobulin can be given as a single therapeutic agent during the induction or maintenance phases of treatment to patients with leukemia resistant to other therapeutic combinations.