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Expression of two natural killer cell antigens, H-25 and H-366, by human immature myeloid cells and by erythroid and granulocytic/monocytic colony-forming units.

Two monoclonal antibodies (MoAbs), H-25 and H-366, shown previously to react with human peripheral blood large granular lymphocytes with natural killer (NK) cell activity and some peripheral blood monocytes, have now been shown to also react with a significant proportion of the myeloid and erythroid precursor cells in human bone marrow and peripheral blood. In FACS IV cell sorting and immune rosetting of bone marrow cells, the antigens recognized by H-25 and H-366 were found to be expressed on most blasts and promyelocytes but sequentially fewer of the more mature cells of the myeloid lineage. Both antigens were also found on most monocytes but only a minor proportion of lymphoid and nucleated red cells in the bone marrow. In vitro assays detecting hematopoietic colony-forming units revealed that these antigens are expressed by virtually all mature erythroid colony-forming units (day-7 CFU-E), and the majority of the more primitive erythroid burst forming units (day-14 BFU-E). H-25 but not H-366 was also found on a variable proportion of the day-7 and day-14 granulocytic/monocytic colony-forming units (CFU-GM) in the bone marrow. The same type of precursor cells are also found in the H-25 and H-366 positive cell populations isolated from peripheral blood. In preliminary testing of cells from acute leukemic patients, FACS analysis showed that both antigens are also expressed on leukemic cells from patients with T cell acute lymphocytic leukemia and with myeloid leukemias. These studies demonstrate that the H-25 and H-366 positive NK cells in the peripheral blood retain some of the cell surface properties of early hematopoietic precursor cells, thus providing further evidence supporting the bone marrow origin of NK cells.

Antibodies, Monoclonal↗

Everolimus is a potent inducer of erythroid differentiation and gamma-globin gene expression in human erythroid cells.

We studied the effects of everolimus on the erythroid differentiation of human leukaemic K562 cells and on the cultures of erythroid progenitors derived from the peripheral blood of beta-thalassaemia patients. A quantitative real-time reverse-transcription polymerase chain reaction assay was employed for the quantification of the accumulation of globin mRNAs. The results obtained demonstrate that everolimus is a potent inducer of the erythroid differentiation of K562 cells. Erythroid induction is associated with an increase in alpha- and gamma-globin mRNAs. In erythroid precursor cells from 4 beta-thalassaemia patients, everolimus stimulated a preferential increase (ranging from 1.8- to 7.2-fold) in gamma-globin mRNA. Only minor effects were observed on the expression of alpha-globin genes. These results, in our opinion, are of interest as this compound is already employed in clinical trials as an anti-rejection agent following kidney transplantation. These data suggest that everolimus warrants further evaluation as a potential therapeutic drug in the treatment of beta-thalassaemia.

Adult↗

Ca2+/calmodulin-dependent and -independent down-regulation of c-myb mRNA levels in erythropoietin-responsive murine erythroleukemia cells. The role of calcineurin.

Down-regulation of c-myb mRNA levels by [Ca2+]i-increasing agents (A23187, thapsigargin, cyclopiazonic acid) and erythropoietin was comparatively studied in the erythropoietin-responsive murine erythroleukemia cell line, ELM-I-1. The Ca2+-induced suppression of c-myb mRNA could be inhibited by the calmodulin antagonists trifluoperazine and calmidazolium, as well as by cyclosporin A, an inhibitor of the Ca2+/calmodulin-dependent protein phosphatase 2B (calcineurin). KN-62, an inhibitor of Ca2+/calmodulin-dependent protein kinases, did not antagonize the Ca2+-mediated decrease in c-myb mRNA. In cyclosporin A-treated ELM-I-1 cells, a close correlation could be demonstrated between the antagonization of the Ca2+ effect on c-myb mRNA levels and inhibition of the calcineurin phophatase activity. On the other hand, FK506, which did not inhibit calcineurin activity in ELM-I-1 cells, failed to prevent the Ca2+-mediated decrease in c-myb mRNA. The erythropoietin-induced down-regulation of c-myb mRNA levels could be demonstrated also in the presence of EGTA and was resistant to calmodulin antagonists and cyclosporin A. In addition, no increase in [Ca2+]i was observed in ELM-I-1 cells in response to erythropoietin. Cyclosporin A inhibited the Ca2+-induced hemoglobin production, while the erythropoietin-mediated increase in hemoglobin synthesis was not affected. The results indicate that the Ca2+-induced decrease in c-myb mRNA and increase in hemoglobin synthesis is mediated by calcineurin, while these effects of erythropoietin occur independently of Ca2+ in ELM-I-1 cells. Calcineurin may be involved in the regulation of c-myb expression in erythroid precursor cells and Ca2+ signals via calcineurin may positively modulate the differentiation inducing action of erythropoietin.

Animals↗

Response of uraemic bone marrow cells to erythropoietin in vitro.

In vitro culture technique of bone marrow cells has been applied to study the cause of anemia in uraemic patients on maintenance haemodialysis. Incorporation of 59Fe into haem in bone marrow cells of the patients in the presence of erythropoietin, as well as the inhibitory effect of their plasma on the response of normal bone marrow cells to erythropoietin, was examined. Increase in haem synthesis rate by erythropoietin in the bone marrow cells of uraemic patients (n 14; 7.9 +/- 1.4) wasnot significantly different from that in normal bone marrow cells (n 9; 5.9 +/- 1.4,p greater than 0.05), thus indicating the presence of erythroid precursor cells with normal responsiveness to erythropoetin in uraemic patients. All the plasma from uraemic patients inhibited, in dose-dependent way, the response of normal bone marrow cells to erythropoietin. Levels of erythropoietin in the plasma samples of uraemic patients were much lower than those of the patients with iron deficiency anaemia with comparable Hb concentrations. On the basis of these results, the humoral inhibitory factor appears to play a significant role in the pathogenesis of renal anaemia, in addition to the low level of circulating erythropoietin.

Adolescent↗

[Diphenylhydantoin-induced pure red cell aplasia after neurological surgery: report of two cases].

Pure red cell aplasia (PRCA) is characterized by severe anemia, reticulocytopenia, marked selective hypoplasia of the erythroid precursor cells in the bone marrow and normal peripheral leukocyte and platelet counts. We reported two cases of diphenylhydantoin (DPH)-induced PRCA after neurological surgery. They recovered completely with discontinuance of DPH therapy. Neurosurgeons should be aware of this side effect because most reported cases of PRCA have occurred about a few months after neurological surgery under general anaesthesia and DPH therapy.

Aged↗

Review of a novel hematopoietic cytokine, interleukin-11.

The novel stromal cell factor, IL-11, has been reported to have diverse effects on the lymphopoietic and myeloid/erythroid cells in vitro. These include expansion of T cell-dependent Ig-secreting B cells, proliferation and differentiation of megakaryocytic progenitors and of a variety of myeloid and erythroid precursor cells, and multiplication of pluripotential hematopoietic progenitors. In addition, IL-11 inhibits adipogenesis in vitro. In vivo administration of IL-11 elevated the number of circulating neutrophils and platelets and increased the number of megakaryocytes in the spleens of normal mice.

Adipose Tissue↗

A palindromic regulatory site within vertebrate GATA-1 promoters requires both zinc fingers of the GATA-1 DNA-binding domain for high-affinity interaction.

GATA-1, a transcription factor essential for the development of the erythroid lineage, contains two adjacent highly conserved zinc finger motifs. The carboxy-terminal finger is necessary and sufficient for specific binding to the consensus GATA recognition sequence: mutant proteins containing only the amino-terminal finger do not bind. Here we identify a DNA sequence (GATApal) for which the GATA-1 amino-terminal finger makes a critical contribution to the strength of binding. The site occurs in the GATA-1 gene promoters of chickens, mice, and humans but occurs very infrequently in other vertebrate genes known to be regulated by GATA proteins. GATApal is a palindromic site composed of one complete [(A/T)GATA(A/G)] and one partial (GAT) canonical motif. Deletion of the partial motif changes the site to a normal GATA site and also reduces by as much as eightfold the activity of the GATA-1 promoter in an erythroid precursor cell. We propose that GATApal is important for positive regulation of GATA-1 expression in erythroid cells.

Amino Acid Sequence↗

Dose response and time course of carboplatin-induced micronucleated polychromatic erythrocytes in the cat: implications for combination carboplatin chemotherapy.

The dose response and time course of micronucleated polychromatic erythrocytes (mPCE) in cat peripheral blood induced by various doses (150-250 mg/m2) of carboplatin in vivo was determined. The data indicate that carboplatin produced a significant (p < 0.05) dose-dependent increase in the number of mPCE over baseline values; however, the times following carboplatin administration when mPCE were first observed differed significantly (p < 0.05) between the three carboplatin dose groups. mPCE were present in significantly greater numbers (p < 0.05) on smears at an earlier time interval following a single carboplatin dose of 150 mg/m2 than for a dose of either 200 or 250 mg/m2. The peak number of mPCE occurred on days 7, 14 and 17.5 following administration of a carboplatin dose of 150, 200 and 250 mg/m2, respectively. The pattern of time course delay following carboplatin administration suggests that the block of erythropoietic stem cells in G2 is dose dependent. Indeed, the administration of carboplatin arrested the cell cycle in the G2 phase and, at higher doses, diminished the number of cycling erythroid precursor cells. mPCE were apparent in blood smears only after recovery from this arrest and resumption of replication. This observation has implications for the scheduling of carboplatin administration when used in combination with other anticancer drugs.

Animals↗

DNA methylation in promoter regions of red cell membrane protein genes in healthy individuals and patients with hereditary membrane disorders.

The methylation state of 5'-CG-3' sites is known to be linked to the regulation of promoter function by modulating DNA-protein interactions and to the structure of chromatin. As part of a project to determine methylation patterns in the human genome, we examined the methylation profiles of several genes for human erythroid membrane proteins: ELB42 (protein 4.2), EPB3 (band 3), SPTB gene (beta-spectrin), and ANK1 (ankyrin). The bisulfite protocol of the genomic sequencing method was applied. The number of 5'-CG-3' dinucleotides was the most abundant in SPTB and ANK1, much less in EPB3, and the least in ELB42. In the DNA of peripheral blood mononuclear cells from healthy individuals, the promoter regions of EPB3 and ELB42 were extensively methylated, but the SPTB and ANK1 promoters were totally unmethylated. We also investigated methylation profiles in peripheral blood mononuclear cells from patients with red cell membrane diseases, such as complete protein 4.2 deficiency due to ELB42 mutations, hereditary spherocytosis with EPB3 mutations, and hereditary elliptocytosis with SPTB mutations. The DNA methylation states in these genes of erythroid cells, which we obtained at the second phase of the 2-phase liquid culture of erythroid precursor cells in the peripheral blood, were essentially identical or very similar to those of peripheral blood mononuclear cells. In disease states, the DNA methylation profiles of these red cell membrane protein genes were essentially not different from those in healthy individuals (statistically not significant).

Anemia↗

Purification of common acute lymphoblastic leukemia antigen positive cells from normal human bone marrow.

Mononuclear cells expressing the common acute lymphoblastic leukemia antigen (CALLA) were purified from normal adult human bone marrow, where they constitute a small fraction of the total population. This was accomplished by a two-step purification from Ficoll-Hypaque-isolated mononuclear cells. Isolated mononuclear cells were first labeled with a mixture of monoclonal antibodies (MoAb) specific for myeloid and erythroid precursor cells, and immune rosettes were then formed with sheep erythrocytes coated with rabbit anti-mouse antibodies (R/M-SRBC). Sedimentation through Ficoll-Hypaque then eliminated the majority of mature myeloid cells. The second step consisted of labeling the remaining rosette-negative cells with CALLA-specific MoAb and purifying CALLA+ cells by fluorescence activated cell sorting. Alternatively, CALLA+ cells were purified in a second R/M-SRBC rosette sedimentation step. The purified CALLA+ cells, which morphologically were medium to large lymphoid cells, were subsequently studied using dual fluorescence techniques to identify surface markers as well as intracytoplasmic staining to detect terminal deoxynucleotidyl transferase enzyme (TdT) and intracytoplasmic mu. While the CALLA+ cell suspensions contained very few mature myeloid cells or T lymphocytes, the finding that 5% to 11% of them were cyto-mu+ and 13% to 22% expressed the B1 differentiation antigen clearly indicated that at least some of these cells were B cell precursors. Because 48% to 63% of the cells were TdT+ and practically all of them expressed Ia antigen, it appears that these cells are a mixture of very early lymphoid precursor cells as well as more differentiated pre-B cells. The phenotype of these normal cells is very similar to that of common ALL cells. Differences in the surface marker phenotypes between adult and fetal CALLA+ cells that have previously been purified were also identified.

Adult↗

Surface antigens defined by monoclonal antibodies as tumor markers in human leukemia.

The detection of surface-linked antigenic determinants by heteroantisera has greatly contributed to a better understanding of the heterogeneity of benign and malignant hematopoietic cells. The difficulties encountered in rendering these heteroantisera specific for a unique cell surface component have been a major drawback to a more rapid development of immunologic cell typing. With the introduction of hybridoma technology, it became possible to obtain monoclonal antibodies and markedly improve immunologic cell typing. We have, therefore, used this new technology for the production of monoclonal antibodies against human leukocyte surface antigens. This paper describes four cell type-specific monoclonal antibodies, which turned out to be very useful reagents in leukemia diagnosis. One of these antibodies, VIM-D5, is directed against a myeloid cell surface antigen. VIL-A1 is specific for the common acute leukemia associated antigen. VIB-C5 recognizes B-cell differentiation antigen and VIE-G4 is specific for glycophorin A, and thus detects erythroid precursor cells.

Antibodies, Monoclonal↗

Immunization with a single T helper cell epitope abrogates Friend virus-induced early erythroid proliferation and prevents late leukemia development.

Synthetic peptide vaccines containing a single Th cell epitope identified in the gp70 envelope glycoprotein of Friend murine leukemia helper virus induced potent protective immunity against Friend virus infection. H-2a/b mice immunized by a single s.c. injection of the CFA emulsion containing a peptide that represented the N-terminal gp70 epitope recovered slowly from initial development of splenomegaly, and most did not develop late leukemia, whereas most of the control mice given an injection of CFA alone showed sustained leukemic splenomegaly after the challenge with Friend virus. The mice of the same genetic background immunized with the C-terminal Th cell epitope by a single injection of a separate synthetic peptide eliminated virus-producing cells from the spleen within 12 days after inoculation of Friend virus complex, and did not develop early splenomegaly or polycythemia. H-2a/a mice were not protected by immunization with either one of the two synthetic peptides. Earlier production and more rapid class switching of virus-neutralizing Abs were observed in H-2a/b mice immunized with the peptide vaccines after the challenge with Friend virus, compared with the responses of the control mice. Detailed kinetic and immunohistopathologic analyses suggested that Th cells might be directly involved in the growth inhibition and elimination of virus-infected erythroid precursor cells.

Amino Acid Sequence↗

Isoniazid-induced pure red cell aplasia.

The clinical courses of four individuals with pure red cell aplasia associated with isoniazid use are described. Erythroblastopenia in these individuals resolved following cessation of this antituberculous therapy. A clonal assay system that quantitates erythroid precursor cells was used to investigate the pathogenesis of the red cell aplasia in three of the patients. Using this technique, however, we were unsuccessful in demonstrating an inhibitory effect of acute phase serum, isoniazid or a combination of the two on erythroid colony formation. We conclude that isoniazid usage alone appears to be associated with a readily reversible form of acquired pure red cell aplasia. In addition, the results of our in vitro studies emphasize the limitations of bone marrow culture systems when used to implicate offending drugs in the production of drug related cytopenias.

Adult↗

Visualization of carbohydrate-binding molecules expressed by myelomono- and erythropoietic cells derived from human bone marrow: an immunoenzymatic double-staining study.

Interactions between human haematopoietic and bone marrow stromal cells are governed by complex carbohydrate-mediated adhesion processes. In order to evaluate corresponding carbohydrate-binding sites on human myelo- and erythropoietic cells which were able to react with mono- or oligosaccharides, we established an immunocytochemical double-staining assay. In a first step, cell lineages were visualized using Lewis(x) (CD15) or glycophorin C-specific monoclonal antibodies. The second step included polyacrylamide-conjugated carbohydrate structures. According to our results, the carbohydrate-binding potential of granulopoietic cells increased during the process of maturation, contrasting a reduction of carbohydrate-binding sites on erythroid precursor cells during differentiation. With respect to previous in vitro studies, these findings shed some light on certain aspects of bone marrow homing as well as on the trafficking of mature cellular elements into circulation. It is tempting to speculate that carbohydrate-mediated adhesion mechanisms may be involved in the various functional defects of progenitor cells in chronic myelogenic leukaemia, especially regarding their complex interactions with the marrow microenvironment.

Binding Sites↗

Differential expression of cell surface binding sites for cholera toxin in acute and chronic leukaemias.

Binding of purified cholera toxin to cell surface receptors has been visualized by an indirect immunofluorescence procedure. Normal nucleated cells from blood, bone marrow and lymphoid tissues, express these receptors with the possible exception of erythroid precursors. Cells from patients with chronic lymphoid or myeloid leukaemias have a normal receptor expression but acute leukaemic cells showed a marked deficiency in cholera toxin binding. Insertion of purified Gm ganglioside into membranes of acute leukaemic cells provided cellular binding sites for the toxin.

Bacterial Toxins↗

A study of erythroid progenitor cells in the bone marrow of Gambian children with falciparum malaria.

There was a wide variation in the number of BFUe and CFUe in the bone marrow of Gambian children with falciparum malaria and moderate or severe anaemia. However, such children were often not deficient in these erythroid progenitors. The number of BFUe in patients who had parasitaemias greater than 1% was significantly lower than that in patients with parasitaemias less than 1%. There was also a statistically significant negative correlation between the number of BFUe and CFUe in the entire group of children studied. When autologous serum (30%, v/v) was used in the culture system, CFUe growth was observed even in the absence of added erythropoietin (EPO), indicating the presence of high levels of EPO or an EPO-like substance in the anaemic sera. It is concluded that children with Plasmodium falciparum malaria show no major abnormality in their erythroid progenitor cells and that the perturbation of erythropoiesis in such children occurs mainly in the morphologically recognizable erythroid precursor cells. The wide variation observed in the number of CFUe and BFUe in different patients, and the correlations between the number of BFUe and parasitaemia and the number of BFUe and CFUe are all probably largely related to the changing clinicopathological situation in patients with malaria and anaemia.

Anemia↗

Erythrocyte production and survival in Rauscher murine leukemia virus-infected BABL/c mice.

Red blood cell production in normal and Rauscher murine leukemia virus-infected mice was investigated using 55Fe as a marker. Using autoradiographic techniques, increases in the percentage of labeling of red blood cells were found in blood smears taken at different time intervals after pulse labeling of the erythroid precursor cells. The total reticulocyte production per unit time is more than 2.8-fold in Rauscher murine leukemia virus-infected mice as compared with that in uninfected mice. The life span of the newly formed cells was measured after [51Cr]chromate labeling of transfused erythrocytes in infected and in control mice. The life span was indicated by time that one-half of the labeled erythrocytes disappeared (t1/2) was reduced to one-quarter of that of erythrocytes of uninfected mice. The functioning of the newly formed cells was analyzed by measuring the glucose utilization versus lactate production and by measuring the activities of a number of enzymes involved in glucose metabolism. Comparison of glucose metabolism in normal and leukemic mice and in mice recovering from artificially induced anemia revealed that the metabolic activity of erythrocytes from leukemic mice corresponds to the activity of young erythrocyte populations. The increased reticulocyte production is, apparently, a result of the degree of anemia in infected animals. This anemia is not compensated for, however, since the loss of erythrocytes surpasses the flux of new red blood cells from the hematopoietic organs into the peripheral blood.

Animals↗

The interaction of erythropoietin with fetal liver cells. II. Inhibition of the erythropoietin effect by interferon.

To investigate the effect of interferon on the proliferation of normal erythroid precursor cells, various interferon preparations were added to mouse fetal liver cells cultured in a liquid microculture system. The effect of interferon was studied using cellular tritiated thymidine incorporation both in the presence and in the absence of erythropoietin. Interferon was found to suppress cellular tritiated thymidine incorporation. The suppression was directly related to the antiviral activity and was not found when control preparations were used. The mechanism of suppression seemed to involve a direct effect on the cells which was dependent of erythropoietin. These studies suggest that the viral inhibitory effects of interferon may also be accompanied by effects on normal cellular proliferation.

Animals↗