Expression of cell-surface HLA-DR, HLA-ABC and glycophorin during erythroid differentiation

Carbon Dots as a Potential Therapeutic Agent for the Treatment of Cancer-Related Anemia

Due to the adverse effects of erythropoietin (EPO) on cancer patient survival, it is necessary to develop new agents that can be used to efficiently manage and treat cancer-related anemia. In this study, novel distinctive carbon dots, J-CDs, derived from jujube are designed, synthesized, and characterized. Based on the obtained results, this material comprises sp² and sp³ carbon atoms, as well as oxygen/nitrogen-based groups, and it specifically promotes the proliferation of erythroid cells by stimulating the self-renewal of erythroid progenitor cells in vitro and in vivo. Moreover, J-CDs have no discernible effects on tumor proliferation and metastasis, unlike EPO. Transcriptome profiling suggests that J-CDs upregulate the molecules involved in hypoxia response, and they also significantly increase the phosphorylation levels of STAT5, the major transducer of signals for erythroid progenitor cell proliferation. Overall, this study demonstrates that J-CDs effectively promote erythrocyte production without affecting tumor proliferation and metastasis; thus, they may be promising agents for the treatment of cancer-related anemia.

Comprehensive phenotyping of erythropoiesis in human bone marrow: Evaluation of normal and ineffective erythropoiesis

Identification of stage-specific erythroid cells is critical for studies of normal and disordered human erythropoiesis. While immunophenotypic strategies have previously been developed to identify cells at each stage of terminal erythroid differentiation, erythroid progenitors are currently defined very broadly. Refined strategies to identify and characterize BFU-E and CFU-E subsets are critically needed. To address this unmet need, a flow cytometry-based technique was developed that combines the established surface markers CD34 and CD36 with CD117, CD71, and CD105. This combination allowed for the separation of erythroid progenitor cells into four discrete populations along a continuum of progressive maturation, with increasing cell size and decreasing nuclear/cytoplasmic ratio, proliferative capacity and stem cell factor responsiveness. This strategy was validated in uncultured, primary erythroid cells isolated from bone marrow of healthy individuals. Functional colony assays of these progenitor populations revealed enrichment of BFU-E only in the earliest population, transitioning to cells yielding BFU-E and CFU-E, then CFU-E only. Utilizing CD34/CD105 and GPA/CD105 profiles, all four progenitor stages and all five stages of terminal erythroid differentiation could be identified. Applying this immunophenotyping strategy to primary bone marrow cells from patients with myelodysplastic syndrome, identified defects in erythroid progenitors and in terminal erythroid differentiation. This novel immunophenotyping technique will be a valuable tool for studies of normal and perturbed human erythropoiesis. It will allow for the discovery of stage-specific molecular and functional insights into normal erythropoiesis as well as for identification and characterization of stage-specific defects in inherited and acquired disorders of erythropoiesis.

Pathophysiologic Mechanisms And Management Of Large Granular Lymphocytic Leukemia Associated Pure Red Cell Aplasia

Large granular lymphocytic leukemia (LGLL) is a chronic clonal lymphoproliferative disease of mature T or NK cells, and produces a variety of hematological abnormalities. Pure red cell aplasia (PRCA) is a rare haematological disease and is one of the most common complications of LGLL. LGLL-associated PRCA may represent a relatively indolent type and may be more common than reported, but its natural history and clinical course have not been well described. The ethnic origin of the patients is an important consideration in determining the relationship between PRCA and LGLL. Guidelines and progresses for management of LGLL-associated PRCA rely on accumulation of empirical experiences, integrative analyses of several cases and clinical trials. The purpose of this review is to evaluate occurrence, possible mechanisms, diagnosis, clinical features, treatments and outcomes of LGLL-associated PRCA.

Knockdown of spliceosome U2AF1 significantly inhibits the development of human erythroid cells

U2AF1 (U2AF35) is the small subunit of the U2 auxiliary factor (U2AF) that constitutes the U2 snRNP (small nuclear ribonucleoproteins) of the spliceosome. Here, we examined the function of U2AF1 in human erythropoiesis. First, we examined the expression of U2AF1 during in vitro human erythropoiesis and showed that U2AF1 was highly expressed in the erythroid progenitor burst-forming-unit erythroid (BFU-E) cell stage. A colony assay revealed that U2AF1 knockdown cells failed to form BFU-E and colony-forming-unit erythroid (CFU-E) colonies. Our results further showed that knockdown of U2AF1 significantly inhibited cell growth and induced apoptosis in erythropoiesis. Additionally, knockdown of U2AF1 also delayed terminal erythroid differentiation. To explore the molecular basis of the impaired function of erythroid development, RNA-seq was performed and the Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis results showed that several biological pathways, including the p53 signalling pathway, MAPK signalling pathway and haematopoietic cell lineage, were involved, with the p53 signalling pathway showing the greatest involvement. Western blot analysis revealed an increase in the protein levels of downstream targets of p53 following U2AF1 knockdown. The data further showed that depletion of U2AF1 altered alternatively spliced apoptosis-associated gene transcripts in CFU-E cells. Our findings elucidate the role of U2AF1 in human erythropoiesis and reveal the underlying mechanisms.

CD71+ erythroid cells from neonates born to women with preterm labor regulate cytokine and cellular responses

Neonatal CD71+ erythroid cells are thought to have immunosuppressive functions. Recently, we demonstrated that CD71+ erythroid cells from neonates born to women who underwent spontaneous preterm labor (PTL) are reduced to levels similar to those of term neonates; yet, their functional properties are unknown. Herein, we investigated the functionality of CD71+ erythroid cells from neonates born to women who underwent spontaneous preterm or term labor. CD71+ erythroid cells from neonates born to women who underwent PTL displayed a similar mRNA profile to that of those from term neonates. The direct contact between preterm or term neonatal CD71+ erythroid cells and maternal mononuclear immune cells, but not soluble products from these cells, induced the release of proinflammatory cytokines and a reduction in the release of TGF-β. Moreover, PTL-derived neonatal CD71+ erythroid cells (1) modestly altered CD8+ T cell activation; (2) inhibited conventional CD4+ and CD8+ T-cell expansion; (3) suppressed the expansion of CD8+ regulatory T cells; (4) regulated cytokine responses mounted by myeloid cells in the presence of a microbial product; and (5) indirectly modulated T-cell cytokine responses. In conclusion, neonatal CD71+ erythroid cells regulate neonatal T-cell and myeloid responses and their direct contact with maternal mononuclear cells induces a proinflammatory response. These findings provide insight into the biology of neonatal CD71+ erythroid cells during the physiologic and pathologic processes of labor.

Marine Sponge Natural Products with Anticancer Potential: An Updated Review

Despite the huge investment into research and the significant effort and advances made in the search for new anticancer drugs in recent decades, cancer cure and treatment continue to be a formidable challenge. Many sources, including plants, animals, and minerals, have been explored in the oncological field because of the possibility of identifying novel molecular therapeutics. Marine sponges are a prolific source of secondary metabolites, a number of which showed intriguing tumor chemopreventive and chemotherapeutic properties. Recently, Food and Drug Administration-approved drugs derived from marine sponges have been shown to reduce metastatic breast cancer, malignant lymphoma, and Hodgkin's disease. The chemopreventive and potential anticancer activity of marine sponge-derived compounds could be explained by multiple cellular and molecular mechanisms, including DNA protection, cell-cycle modulation, apoptosis, and anti-inflammatory activities as well as their ability to chemosensitize cancer cells to traditional antiblastic chemotherapy. The present article aims to depict the multiple mechanisms involved in the chemopreventive and therapeutic effects of marine sponges and critically explore the limitations and challenges associated with the development of marine sponge-based anticancer strategy.

Distinct roles for TET family proteins in regulating human erythropoiesis

The ten-eleven translocation (TET) family of proteins plays important roles in a wide range of biological processes by oxidizing 5-methylcytosine (5mC) to 5-hydroxy-methylcytosine. However, their function in erythropoiesis has remained unclear. We show here that TET2 and TET3 but not TET1 are expressed in human erythroid cells, and we explore the role of these proteins in erythropoiesis. Knockdown experiments revealed that TET2 and TET3 have different functions. Suppression of TET3 expression in human CD34⁺ cells markedly impaired terminal erythroid differentiation, as reflected by increased apoptosis, the generation of bi/multinucleated polychromatic/orthochromatic erythroblasts, and impaired enucleation, although without effect on erythroid progenitors. In marked contrast, TET2 knockdown led to hyper-proliferation and impaired differentiation of erythroid progenitors. Surprisingly, knockdown of neither TET2 nor TET3 affected global levels of 5mC. Thus, our findings have identified distinct roles for TET2 and TET3 in human erythropoiesis, and provide new insights into their role in regulating human erythroid differentiation at distinct stages of development. Moreover, because knockdown of TET2 recapitulates certain features of erythroid development defects characteristic of myelodysplastic syndromes (MDSs), and the TET2 gene mutation is one of the most common mutations in MDS, our findings may be relevant for improved understanding of dyserythropoiesis of MDS.

Unexpected role for p19INK4d in posttranscriptional regulation of GATA1 and modulation of human terminal erythropoiesis

Terminal erythroid differentiation is tightly coordinated with cell-cycle exit, which is regulated by cyclins, cyclin-dependent kinases, and cyclin-dependent kinase inhibitors (CDKI), yet their roles in erythropoiesis remain to be fully defined. We show here that p19^INK4d, a member of CDKI family, is abundantly expressed in erythroblasts and that p19^INK4d knockdown delayed erythroid differentiation, inhibited cell growth, and led to increased apoptosis and generation of abnormally nucleated late-stage erythroblasts. Unexpectedly, p19^INK4d knockdown did not affect cell cycle. Rather, it led to decreased expression of GATA1 protein. Importantly, the differentiation and nuclear defects were rescued by ectopic expression of GATA1. Because the GATA1 protein is protected by nuclear heat shock protein family (HSP) member HSP70, we examined the effects of p19^INK4d knockdown on HSP70 and found that p19^INK4d knockdown led to decreased expression of HSP70 and its nuclear localization. The reduced levels of HSP70 are the result of reduced extracellular signal-regulated kinase (ERK) activation. Further biochemical analysis revealed that p19^INK4d directly binds to Raf kinase inhibitor PEBP1 and that p19^INK4d knockdown increased the expression of PEBP1, which in turn led to reduced ERK activation. Thus we have identified an unexpected role for p19^INK4d via a novel PEBP1-p-ERK-HSP70-GATA1 pathway. These findings are likely to have implications for improved understanding of disordered erythropoiesis.

An ordered sequence of expression of human MHC class-II antigens during B-cell maturation?

Studies with monoclonal antibodies confirm that human MHC class-II antigens are encoded by at least three pairs of loci. Here Keith Guy and Veronica van Heyningen suggest that as B cells mature theproducts of these loci are expressed in the sequence SB → DR → DC antigens - a sequence which parallels the order of the genes on chromosome 6.

Isolation and functional characterization of human erythroblasts at distinct stages: implications for understanding of normal and disordered erythropoiesis in vivo

Terminal erythroid differentiation starts from morphologically recognizable proerythroblasts that proliferate and differentiate to generate red cells. Although this process has been extensively studied in mice, its characterization in humans is limited. By examining the dynamic changes of expression of membrane proteins during in vitro human terminal erythroid differentiation, we identified band 3 and α4 integrin as optimal surface markers for isolating 5 morphologically distinct populations at successive developmental stages. Functional analysis revealed that these purified cell populations have distinct mitotic capacity. Use of band 3 and α4 integrin enabled us to isolate erythroblasts at specific developmental stages from primary human bone marrow. The ratio of erythroblasts at successive stages followed the predicted 1:2:4:8:16 pattern. In contrast, bone marrows from myelodysplastic syndrome patients exhibited altered terminal erythroid differentiation profiles. Thus, our findings not only provide new insights into the genesis of the red cell membrane during human terminal erythroid differentiation but also offer a means of isolating and quantifying each developmental stage during terminal erythropoiesis in vivo. Our findings should facilitate a comprehensive cellular and molecular characterization of each specific developmental stage of human erythroblasts and should provide a powerful means of identifying stage-specific defects in diseases associated with pathological erythropoiesis.

Mapping cell surface antigen expression of haemopoietic progenitor cells using monoclonal antibodies

A library of monoclonal antibodies which show selective reactivity with particular cells or gene products (e.g. HLA-DR, glycophorin) of different cell lineages in the haemopoietic system has been compiled. Using these probes in conjunction with the fluorescence-activated cell sorter (FACS) the pattern and sequence of cell surface antigenic expression on haemopoietic progenitor cells have been mapped. A cell is identified in bone marrow which has a unique membrane phenotype and the nuclear enzyme terminal deoxynucleotidyl transferase. Its composite phenotype is identical to that seen in the common variant of acute lymphoblastic leukaemia (ALL). It is suggested that this cell is a putative B lineage progenitor which provides the major target for ALL. Detailed analysis of erythroid differentiation with monoclonal antibodies on the FACS reveals an intriguing pattern of antigenic expression in which HLA-DR, glycophorin and band III appear in sequence. HLA-DR (Ia-like antigen) may be present on all or most committed haemopoietic progenitor cells and could play an important role in cell interactions regulating early haemopoiesis.

Production of hemo- and immunoregulatory cytokines by erythroblast antigen+ and glycophorin A+ cells from human bone marrow

BACKGROUND

Erythroid nuclear cells (ENC) of the bone marrow (BM) have not previously been considered as important producers of wide spectrum of haemo- and immunoregulatory cytokines. The aim of the current work was to confirm the production of the main hemo- and immunoregulatory cytokines in human ENC from BM.

RESULTS

We used native human BM ENC in our experiments. We for the first time have shown, that the unstimulated erythroblasts (Gl A+ or AG-EB+) produced a wide spectrum of immunoregulatory cytokines. Human BM ENC produce cytokines such as interleukin (IL)-1beta, IL-2, IL-4, IL-6, interferon (IFN)-gamma, transforming growth factor (TGF)-beta1, tumor necrosis factor (TNF)-alpha and IL-10. They can be sub-divided into glycophorin A positive (Gl A+) and erythroblast antigen positive (AG-EB+) cells. To study potential differences in cytokine expression between these subsets, ENC were isolated and purified using specific antibodies to Gl A and AG-EB and the separated cells were cultivated for 24 hours. The cytokine contents of the supernatant were measured by electrochemiluminescence immunoassay. Quantitative differences in TGF-beta1 and TNF-alpha production were found between Gl A+ and AG-EB+ BM ENC. Furthermore, in vitro addition of erythropoietin (EPO) reduced IFN-gamma and IL-2 production specifically by the AG-EB+ ENC. Thus, Gl A+ and AG-EB+ ENC produce IL-1beta, IL-2, IL-4, IL-6, IFN-gamma, TGF-beta1 and TNF-alpha. Gl A+ ENC also produce IL-10.

CONCLUSION

Cytokine production by erythroid nuclear cells suggests that these cells might be involved in regulating the proliferation and differentiation of hematopoietic and immunocompetent cells in human BM.

Smenospongine, a spongean sesquiterpene aminoquinone, induces erythroid differentiation in K562 cells

The differentiation of K562 chronic myelogenous leukemia (CML) cells by smenospongine, which is a sesquiterpene aminoquinone isolated from a marine sponge, was examined. Smenospongine increased hemoglobin production in K562 cells at concentrations of 3-15 microM. In addition, flow cytometric analysis of smenospongine-treated K562 cells with FITC-labeled glycophorin A antibody showed an increase of glycophorin A expression, a marker for erythroid differentiation. Cell-cycle analysis showed G1 arrest in K562 cells after treatment with smenospongine for 24 h. The effect on expression of CIP/KIP family cyclin-dependent kinase inhibitors was investigated by Western blotting analysis and the result showed increased expression of p21, which is known to play an important role in differentiation. Furthermore, smenospongine was also found to inhibit the phosphorylation of Crkl, a substrate of Bcr-Abl tyrosine kinase, which is known as a causative protein of CML. In conclusion, our investigation indicated that smenospongine induced the differentiation of K562 cells into erythroblasts along with cell-cycle arrest at G1 phase and the mechanism might be attributed to the increased expression of p21.

Chimaerism and erythroid marker expression after microinjection of human acute myeloid leukaemia cells into murine blastocysts

It has been suggested that the embryonic microenvironment can control the survival and the transformed phenotype of tumour cells. Here, we addressed the hypothesis that the murine embryonic microenvironment can induce the differentiation of human tumour cells. To examine such interactions, we injected human leukaemic cells into preimplantation murine blastocysts at embryonic day 3.5 of gestation (E3.5). Microinjection of human KG-1 myeloid leukaemia cells and primary human acute myeloid leukaemia (AML) cells led to the generation of chimaeric embryos and adults. We observed that in E12.5 murine embryos, KG-1 cells were preferentially detected in yolk sac and peripheral blood, while primary AML cells mainly seeded the aorta gonad mesonephros region of chimaeric embryos. Analysis of the donor contribution in 15 different adult tissues showed that progeny of primary AML cells seeded to various haematopoietic and nonhaematopoietic tissues. Chimaeric embryos and adults showed no apparent tumour formation. Furthermore, analysis of chimaeric E12.5 embryos revealed that the progeny of human KG-1 cells activated erythroid-specific human globin and glycophorin A expression. In summary, our data indicate that human AML cells activate markers of erythroid differentiation after injection into early murine embryos.

Expression of signal transduction proteins during the differentiation of primary human erythroblasts

The high number (>10(8-10)) of primary human pro-erythroblasts (CD36high/CD235alow) obtainable in HEMA culture (Migliaccio et al., 2002) is exploited here to analyse the expression of proteins implicated in erythropoietin (EPO)-signalling (STATs, PI-3K, and PLCs) during the process of erythroid maturation. Human pro-erythroblasts progressed in 4 days of culture with EPO into basophilic- (CD36high/CD235amedium, 24 h), polychromatic-(CD36high/CD235ahigh, 48 h), and, finally, orthochromatic-(CD36low/CD235ahigh, 72-96 h) erythroblasts. During this maturation, STAT-1 was expressed up to the orthochromatic stage, expression of STAT-5, as well as of its target proteins BclxL and IRF1, remained constant up to 48 h (polychromatic-erythroblasts) but decreased by 96 h (orthochromatic-erythroblasts), while that of STAT-3 decreased constantly from 24 h on and became undetectable by 96 h. Expression of PI-3K rapidly decreased with differentiation since only 50% of original protein levels were detected by 48 h. On the other hand, among the members of PLC families investigated, PLC beta4 was not expressed, PLC beta2, delta1, and gamma2 were expressed at constant levels throughout the maturation process, while expression of PLC beta3 and of PLC gamma1 decreased, as PI-3K, by 24 h and that of PLC beta1 was induced by 6 h and became undetectable by 24 h. In conclusion, these data depict the dynamic signalling scenario associated with the maturation of erythroid cells and provide the first indication that members of PLC families (PLC beta1, beta3, and gamma1) might be involved in the control of erythroid differentiation in humans.

Flow cytometric-based isolation of nucleated erythroid cells during maturation: an approach to cell surface antigen studies

Nucleated red blood cells (NRBCs) are involved in normal physiologic processes, as well as in several malignancies. They are usually counted manually under the microscope. However, blood sample manipulation may be a source of variability and manual counting is imprecise, time-consuming, and subjective. To improve identification of CD45-negative cells, we used a flow cytometry technique that avoids the addition of lysing reagents and stains viable cell nuclei. We applied this method for counting and isolating NRBC subpopulations in whole blood samples, using DNA/RNA viable staining to discriminate nonnucleated erythroid cells and debris. NRBC counts gave 197.95 cells per mm(3) in mobilized peripheral blood samples (1.00%, n = 20), 3897.59 cells per mm(3) in leukapheresis products (3.08%, n = 20), and 765.21 cells per mm(3) in cord blood samples (6.09%, n = 20). Normal bone marrow counts were 5449.42 cells per mm(3) (11.76%, n = 20). Scatter profiles showed three distinct populations, from early to late-stage erythroblasts, consisting of erythroblasts, orthochromatic erythroblasts, and ejected nuclei, as confirmed by Wright-Giemsa staining. In addition, flow cytometry immunophenotyping showed that glycophorin A was expressed dimly on NRBCs during maturation. These findings point to the feasibility of live NRBCs studies, which offer great potential for a wide range of disciplines.

Evidence for discoordinate regulation of the HLA-DPB1 gene

Characterization of cell lines derived from patients with type II bare lymphocyte syndrome, a pathological state in which the constitutive and inducible expression of HLA class II antigens is lacking, has permitted the identification of several trans-acting factors involved in the coordinated regulation of HLA class II genes. Although an increasing body of evidence has pointed to the existence of a discoordinate regulation of HLA class II loci, the mechanisms underlying such regulation are essentially unknown. In the present study, 45.EM2, a mutant lymphoblastoid cell line with a new pattern of HLA discoordinate expression is characterized. 45.EM2 expresses HLA-DR and -DQ but fails to express HLA-DP. The absence of HLA-DP expression in 45.EM2 is the result of a transcriptional defect, leading to a lack of DPB1 mRNA. By contrast, DPA1 transcription in this LCL is not impaired. The characteristics of 45.EM2 described here suggest the existence of a specific trans-acting factor involved in the control of DPB1 gene expression.

Absence of major histocompatibility class II expression does not impair hematopoiesis in mice

OBJECTIVE

Major histocompatibility class II (MHC II) molecules are among the earliest antigens to be expressed in hematopoietic progenitor cells; however, the functional role of these molecules in hematopoiesis remains controversial. We examined the role of MHC II antigens during hematopoiesis using a mouse model of MHC II deficiency related to the absence of the critical transcriptional activator, CIITA.

METHODS

Sca-1(-), Sca-1(+)lin(+), and Sca-1(+)lin(-) populations of marrow cells from CIITA(-)(/-) and wild-type mice were analyzed by immunofluorescence for MHC II expression. Hematopoietic capacity was assessed in CIITA(-/-) and wild-type mice by CFU-S, CFU-GM, and radiation sensitivity assays.

RESULTS

Flow cytometric characteristics of hematopoietic progenitors from CIITA(-/-) and wild-type mice were identical except for the absence of MHC II expression in CIITA null mice. There were no significant differences in capacity for hematopoietic reconstitution and clonogenicity as measured by radiation sensitivity, CFU-S, and CFU-GM assays among CIITA(-/-) and wild-type mice.

CONCLUSIONS

These experiments show that downregulation of MHC II gene transcription does not effectively alter normal hematopoiesis, and provide strong evidence that MHC II expression on hematopoietic progenitors is not required for normal hematopoietic development.

Differentiation in chronic myelogenous leukemia cell K562 by spongean sesterterpene

Scalarane-type sesterterpenes, PHC-1-PHC-7, which have been isolated from a marine sponge, increased hemoglobin production in human chronic myelogenous leukemia cell line K562 at the concentration of 0.1-5 microg/ml. PHC-1, the major constituent, induced the expression of glycophorin A and the enucleation for K562 cells. These sesterterpenes were found to induce erythroid differentiation in K562 cells. In addition, PHC-1 induced G1 arrest of the cell cycle of K562 cells.

Tolerance to solid organ transplants through transfer of MHC class II genes

Donor/recipient MHC class II matching permits survival of experimental allografts without permanent immunosuppression, but is not clinically applicable due to the extensive polymorphism of this locus. As an alternative, we have tested a gene therapy approach in a preclinical animal model to determine whether expression of allogeneic class II transgenes (Tg's) in recipient bone marrow cells would allow survival of subsequent Tg-matched renal allografts. Somatic matching between donor kidney class II and the recipient Tg's, in combination with a short treatment of cyclosporine A, prolonged graft survival with DR and promoted tolerance with DQ. Class II Tg expression in the lymphoid lineage and the graft itself were sequentially implicated in this tolerance induction. These results demonstrate the potential of MHC class II gene transfer to permit tolerance to solid organ allografts.

The monoclonal antibody TER-119 recognizes a molecule associated with glycophorin A and specifically marks the late stages of murine erythroid lineage

The antigen specificity of a rat monoclonal antibody TER-119 was investigated. In adult mice, TER-119 reacted with mature erythrocytes, 20-25% of bone marrow cells and 2-3% of spleen cells but not with thymocytes nor lymph node cells. In fetal haematopoietic tissues, 30-40% of d 10 yolk sac cells, 80-90% of d 14 fetal liver cells and 40-50% of newborn liver cells were reactive with TER-119. TER-119+ cells in adult bone marrow expressed significant levels of CD45 but not myeloid (Mac-1, Gr-1) or B-cell (B220) markers. Morphological examination and haematopoietic colony-forming assays for isolated TER-119+ cells revealed that TER-119 reacts with erythroid cells at differentiation stages from early proerythroblast to mature erythrocyte, but not with cells showing typical erythroid blast-forming unit (BFU-E) and erythroid colony-forming unit (CFU-E) activities. Erythroleukaemia cell lines do not express the TER-119 antigen even after stimulation with dimethylsulphoxide. TER-119 immunoprecipitated protein bands with molecular masses of 110 kDa, 60 kDa, 52 kDa and 32 kDa from erythrocyte membrane, whereas only a 52-kDa band was detected by TER-119 in Western blot analysis. Further molecular and cellular analyses indicated that the TER-119 antigen is a molecule associated with cell-surface glycophorin A but not with glycophorin A itself.

Time-course expression of polypeptides carrying blood group antigens during human erythroid differentiation

The time course expression of blood group antigens was examined by flow cytometry using a two-phase liquid culture system that supports the proliferation and maturation of human erythroid progenitors from adult peripheral blood. The progression towards erythroid differentiation was followed by the expression changes of the transferrin receptor (CD71++) and glycophorin A (GPA+). Four main categories of blood group markers were identified: (i) those characterized by an early expression like ABO (A), Kell (K:2) and Rh50 which were detected in the Epo-independent phase 1, (ii) those including GPC (Gerbich, Ge antigens) and Fy6 which were expressed in the late phase 1, (iii) GPA (MN antigens), Wrb (Band 3/GPA interaction), Rh(D, Cc/Ee) and LW which appeared during the Epo-dependent phase 2 and (iv) those like Jk3 and Lub which were expressed in late phase 2. Regarding blood group molecules exhibiting adhesive properties (LW/ICAM-4, Oka and Lu) the most significant event was a sharp decrease of Oka (neurothelin) expression with the concomitant loss of ICAMs expression during the later stage of differentiation. These studies suggest that Oka, ICAMs and LW might contribute to the adhesive interactions involved in the formation of erythroblastic islands and attachment to stroma cells and the extracellular matrix. We also noted an asynchronous expression of the proteins that compose the core of the Rh complex, since Rh50 glycoprotein was expressed earlier than Rh(D, CE) proteins.

The Expression of Human Blood Group Antigens During Erythropoiesis in a Cell Culture System

Phenotypic analysis of hematopoietic stem and progenitor cells has been an invaluable tool in defining the biology of stem cell populations. We use here flow cytometry to examine the expression of human erythroid-specific surface markers during the maturation of early committed erythroid cells derived from cord blood in vitro. The temporal order of the expression of erythroid specific markers was as follows: Kell glycoprotein (gp), Rh gp, Landsteiner Wiener (LW) gp, glycophorin A (GPA), Band 3, Lutheran (Lu) gp, and Duffy (Fy) gp. The time at which some of these markers appeared suggests possible roles for some of these erythroid-specific polypeptides during the differentiation of these committed progenitors. The early appearance of Kell gp raises the possibility that it may have an important role in the early stages of hematopoiesis or cell lineage determination. Kell gp may also be a useful marker for the diagnosis of erythroleukemia. The late expression of Lu gp suggests it may be involved in the migration of erythroid precursors from the marrow. Fy gp is also expressed late consistent with a role as a scavenger receptor for cytokines in the bone marrow and circulation. Rh c antigen appeared before Rh D antigen, and it is suggested that this may reflect a reorganization of the developing erythroid cell membrane involving the Rh polypeptides and other components, including GPA and Band 3.

The Expression of Human Blood Group Antigens During Erythropoiesis in a Cell Culture System

Phenotypic analysis of hematopoietic stem and progenitor cells has been an invaluable tool in defining the biology of stem cell populations. We use here flow cytometry to examine the expression of human erythroid-specific surface markers during the maturation of early committed erythroid cells derived from cord blood in vitro. The temporal order of the expression of erythroid specific markers was as follows: Kell glycoprotein (gp), Rh gp, Landsteiner Wiener (LW) gp, glycophorin A (GPA), Band 3, Lutheran (Lu) gp, and Duffy (Fy) gp. The time at which some of these markers appeared suggests possible roles for some of these erythroid-specific polypeptides during the differentiation of these committed progenitors. The early appearance of Kell gp raises the possibility that it may have an important role in the early stages of hematopoiesis or cell lineage determination. Kell gp may also be a useful marker for the diagnosis of erythroleukemia. The late expression of Lu gp suggests it may be involved in the migration of erythroid precursors from the marrow. Fy gp is also expressed late consistent with a role as a scavenger receptor for cytokines in the bone marrow and circulation. Rh c antigen appeared before Rh D antigen, and it is suggested that this may reflect a reorganization of the developing erythroid cell membrane involving the Rh polypeptides and other components, including GPA and Band 3.

Prospective identification of erythroid elements in cultured peripheral blood

We have developed a prospective approach to identify the generation of erythroid cells derived from cultured peripheral blood mononuclear cells (PBMC) by monitoring the expression of the cell surface protein CD48. Unpurified populations of PBMC obtained from the buffy coats of normal volunteers were grown in suspension culture in the absence or presence of erythropoietin. A profile of surface CD48 expression permitted a flow cytometric identification of erythropoietin responsive populations at various stages of their maturation. In the absence of erythropoietin (EPO) supplemented media, the CD48- cells represented <5% of the total population of PBMC remaining in culture. In cultures supplemented with 1 U/mL EPO, the mean percentage of CD48- cells increased to 34.7 + 14.9% (p < 0.01) after 14 days in culture. Coordinated CD34 and CD71 (transferrin receptor) expression, morphology, gamma-globin transcription, and colony formation in methylcellulose were observed during the 14-day culture period. Flow cytometric monitoring of bulk cultured PBMC provides a simple and reliable means for the prospective or real-time study of human erythropoiesis.

Delineation of erythropoiesis in normal and malignant bone marrow using monoclonal antibody AS-E1 directed against transferrin receptors (CD71)

We have delineated the erythropoietic compartment in normal and malignant bone marrow (BM) by using the monoclonal antibody (mAb) AS-E1 directed against the transferrin receptor by flow cytometric (FCM) analysis. In normal BM we found a bimodal expression in antigen density with a minor subset (approximately 3%) expressing AS-E1high and a larger subset (approximately 15%) expressing AS-E1low. By fluorescence activated cell sorting, morphological examination of smears stained by immunocytochemistry and by BFU-E assays the AS-E1high fraction was shown to contain cells of erythroid origin (proerythroblasts, basophilic erythroblasts and polychromatic erythroblasts), whereas the AS-E1low fraction consisted mainly of promyelocytes and myelocytes. In patients with malignant hematological disorders we found a more pronounced heterogeneity in the density and the degree of AS-E1low expression compared to normal BM, and to further characterize the AS-E1low cells in patients and to exclude that this broad reactivity interfered with the identification of the AS-E1high cells, we employed triple-color FCM assays with mAbs directed against the myeloid surface markers CD13 and CD66 in addition to AS-E1. In all patients we found that 80-90% of the AS-E1low cells co-expressed CD13 and/or CD66 and thus were of myeloid origin. Finally, we evaluated 2 methods for determination of the AS-E1high subset and found an assay involving forward light scatter and logAS-E1 density to be sufficient. We conclude that AS-E1high is a valid FCM marker for the normal erythropoiesis.

Expression of sialosyl-T and disialosyl-T antigens in erythroid cells

Expression of T, sialosyl-T and disialosyl-T antigens on normal blood and bone marrow cells as well as transformed cells was examined using specific monoclonal antibodies and multidimensional flow cytometry. Both anti-sialosyl-T (QSH1) and anti-disialosyl-T (QSH2) monoclonal antibodies aggregated erythrocytes. The anti-disialosyl-T antibody was specific for the erythroid lineage and did not react with neutrophils, monocytes or T-lymphocytes, while the anti-sialosyl-T antibody reacted with erythroid cells and a subset of T-lymphocytes. The developing erythroid cells in bone marrow showed coordinate expression of glycophorin A and the two carbohydrate chains, sialosyl-T and disialosyl-T. Analysis of neoplastic cells showed that the anti-disialosyl-T antibody only reacted with glycophorin A-positive blasts from erythroleukemia (FAB M6) patients (4/4) and one patient with chronic myeloid leukemia in erythroblastic transformation (CMLET). Leukemic blasts from these patients demonstrated coordinate quantitative expression of glycophorin A and disialosyl-T. The anti-sialosyl-T antibody reacted with glycophorin A-positive blasts from FAB M6 patients (4/4) and one CMLET patient; however, the antibody also reacted with glycophorin A-negative blasts from one FAB M6 and the one CMLET patients and transformed cells from other types of leukemia. The anti-T monoclonal antibody (HH8) did not react with any of the other cells tested. These results indicate that glycophorin A and disialosyl-T expression are tightly linked during normal erythroid development and erythroid leukemogenesis.

Expression of MHC class I and class II antigens in pancreatic adenocarcinomas

The antigens encoded by the major histocompatibility complex (MHC) are cell surface glycoproteins that play a fundamental role in the regulation of the immune response. Anomalous MHC expression in tumor cells has been viewed as an important feature to escape tumor recognition by immune cells. Low or absent MHC class I expression as well as ectopic MHC class II expression have been often observed to correlate with high grade malignancy and metastatic potential in a variety of human cancers. To date, very little investigation of MHC (HLA in man) class I and class II expression in human pancreatic cancer has been reported. We investigated this aspect on frozen sections of 8 pancreatic adenocarcinomas and 18 established in vitro cell lines. HLA class I was expressed in all but two cancers whereas de novo HLA class II expression was detected in 3 of 8 cancers. Interestingly, a hierarchy in the expression of the various subsets of HLA class II was found with HLA- DR > -DP > -DQ. Results on cell lines strongly resembled the ones obtained in cancer tissues. However, a peculiar feature was observed in certain cell lines. HLA class II antigens were expressed in only a few cell lines and in some of them a mixed population of positive and negative cells was found. Sorting and cloning of the two populations confirmed the existence of tumor cell clones with stable and distinct HLA class II phenotype. Taken together, these results indicate the cellular heterogeneity of pancreatic cancer cells with regard to the qualitative and quantitative expression of major histocompatibility complex genes, and may provide new insights for a better understanding of the tumorhost relationships in this extremely severe form of neoplasia.

Cell surface antigen expression in human erythroid progenitors: erythroid and megakaryocytic markers

This review summarizes the changes in cell surface antigen expression during proliferation and differentiation of human erythroid progenitors. The content is based on our experimental data obtained from complement-mediated cytotoxicity assays against hematopoietic progenitors and a combined technique of sequential micromanipulations of paired daughter cells derived from erythroid burst-forming units (BFU-E) and immunostaining with a panel of monoclonal antibodies, as well as from current information. BFU-E has CD34, CD41a (platelet glycoprotein[GP]IIb/IIIa) and CD41b(GPIIb) antigens. Paired daughter cells derived from BFU-E have CD41a, CD41b, CD71 (transferrin receptor) and HLA-DR antigens, but not CD34 or CD33 antigen. The CD36 antigen (thrombospondin receptor or GPIV) is first expressed on the cells after 5 days of culture, in agreement with the report that the anti-CD36 positive fraction contained a greater part of the erythroid colony-forming units (CFU-E). The blood group A antigen is first expressed on cells from aggregates derived from BFU-E after 5 days of culture. Glycophorin A is expressed on cell surface after 7 days of culture when proerythroblasts first appear. Hemoglobin alpha is expressed after 8 days of culture and coincides with the first appearance of basophilic erythroblasts. This review provides useful information on the identification of leukemic cells from poorly differentiated acute leukemias such as early erythroblastic leukemia and acute megakaryoblastic leukemia, and is useful in the understanding of the commitment and differentiation of erythroid and megakaryocytic progenitors in normal hematopoiesis.

Characterization of CD34+HLA-DR-CD38+ and CD34+HLA-DR-CD38- progenitor cells from human umbilical cord blood

In this study we show that depletion of cells expressing mature cell markers, including HLA-DR, followed by positive cell sorting for cells expressing CD34 and CD38, can be used to define functionally distinct hematopoietic cells from human umbilical cord blood (HUCB). The CD34+HLA-DR-CD38+ population contained the majority of directly clonogenic cells, while the optimal ability to maintain long term co-culture with bone marrow stromal cells was present within the CD34+HLA-DR-CD38- population. 1.2 +/- 0.4% of the CD34+HLA-DR-CD38- cells plated at 1 cell/well and grown in the presence of hematopoietic growth factors (HGF) formed hemopoietic colonies. Mesenchymal elements were observed in 20% of these cultures. No cell growth, however, was observed when the CD34+HLA-DR-CD38- cells were cultured in the absence of HGF. This is in contrast with the findings in fetal bone marrow which demonstrated the presence of stem cells that were independent of HGF. Thus, while it is possible to isolate very immature hemopoietic progenitor cells from HUCB defined by the phenotype Lin-CD34+HLA-DR-CD38-, these cells do not appear to exhibit the pluripotentiality of the analogous population reported in fetal bone marrow. We conclude that these cells are absent or at a very small frequency in HUCB.

Distribution of S-100 protein-positive dendritic cells and expression of HLA-DR antigen in transitional cell carcinoma of the urinary bladder in relation to tumour progression and prognosis

The distribution of S-100 protein positive dendritic cells (S100-DCs) in cancer nests and the expression of HLA-DR antigen on cancer cells in 90 patients with transitional cell carcinoma of the urinary bladder were studied immunohistochemically. A dense infiltrate of S100-DCs (more than 10 S100-DCs/high power field) was detected in 47 out of 90 cases, while in the remaining tumours the infiltrate was sparse. HLA-DR positive cancer cells (DR-CCs) were detected in 24 cases, including 16 with dense DR-CCs (more than 100 DR-CCs/high power field); no expression was observed in the remaining tumours. In terms of the numbers of S100-DCs infiltrating the following statistically significant differences were observed: tumour grading G1 > G3, depth of penetration pT0 > pT3; (p < 0.05), G2 > G3, lymphatic invasion - > + and venous invasion - > +; (p < 0.01). A multivariate analysis demonstrated that the most important factor affecting prognosis was distant organ and/or lymph node metastasis (p < 0.01) the number of S100-DCs, with a hazard ratio (HR) of 0.26 (p < 0.01), and the number of DR-CCs with HR of 0.18 (p < 0.05); these were statistically significant. S100-DCs and DR-CCs may be regarded as independent prognostic factors of tumour growth and progression.

Immunoanalysis and quantitation of membrane sialoglycoproteins (glycophorins) in rat erythrocytes and reticulocytes

An enzyme-linked immunosorbent assay (ELISA) for the quantitation of rat erythrocyte membrane sialoglycoproteins (glycophorins) has been developed. Samples of erythrocytes and reticulocytes were analysed using this assay, and response compared among them and purified glycophorins samples. A broadly homologous behaviour of glycophorins was found in both cell types, suggesting the presence in reticulocytes of glycophorin molecules closely similar to those on the erythrocyte. A quantitative evaluation of glycophorins on both cell types yielded comparable levels of these glycoproteins, but with significantly higher values (1.7-fold) for reticulocytes. It is suggested that the lower number of epitopes present on the erythrocyte membrane might be due to the disappearance of some glycophorin-associated antigenic determinants during the maturation of reticulocyte to erythrocyte.

Immunophenotyping of fetal haemopoietic cells permissive for human parvovirus B19 replication in vitro

Human parvovirus B19 is known to inhibit erythroid colony formation in vitro, but the precise stage of differentiation at which erythroid precursors become capable of supporting viral replication has not been accurately determined. In order to address this issue, haemopoietic cells derived from first trimester fetal liver were cultured in medium containing B19 antigen-positive serum. Infected cells were phenotyped by combining immunohistology for cell-type specific antigens with non-isotopic in situ hybridization for B19 nucleic acid. Strong nuclear hybridization signal was detected as early as 8 h after infection in erythroid precursors labelling with antibodies to glycophorin A, glycophorin C, CD43, CD36 and HLA-ABC (pronormoblast or normoblast phenotype). Giant erythroid precursors labelling with the same five antibodies were a pathognomonic feature of infected cultures, but contained relatively little B19 nucleic acid. Hybridization signal was not detected in progenitor cells of more primitive erythroid phenotype or in nuclei of cells of other lineages, though B19 DNA was occasionally localized within the cytoplasm of macrophages. Double-labelling with antibody Ki-67 confirmed that proliferating cells were targets for B19 infection. Co-detection of cell-type specific antigens and viral nucleic acid is a powerful tool for investigating host cell specificity, and suggests that proliferating late erythroid precursors are the only haemopoietic cells fully permissive for B19 infection.

Human erythrocyte glycophorins: protein and gene structure analyses

Human RBCs glycophorins are integral membrane proteins rich in sialic acids that carry blood group antigenic determinants and serve as ligands for viruses, bacteria, and parasites. These molecules have long been used as a general model of membrane proteins and as markers to study normal and pathological differentiation of the erythroid tissue. The RBC glycophorins known as GPA, GPB, GPC, GPD, and GPE have recently been fully characterized at both the protein and the DNA levels, and these studies have demonstrated conclusively that these molecules can be subdivided into two groups that are distinguished by distinct properties. The first group includes the major proteins GPA and GPB, which carry the MN and Ss blood group antigens, respectively, and a recently characterized protein, GPE, presumably expressed at a low level on RBCs. All three proteins are structurally homologous and are essentially erythroid specific. The respective genes are also strikingly homologous up to a transition site defined by an Alu repeat sequence located about 1 Kb downstream from the exon encoding the transmembrane regions. Downstream of the transition site, the GPB and GPE sequences are still homologous, but diverge completely from those of GPA. The three glycophorin genes are organized in tandem on chromosome 4q28-q31, and define a small gene cluster that presumably evolved by duplication from a common ancestral gene. Most likely two sequential duplications occurred, the first, about 9 to 35 million years ago, generated a direct precursor of the GPA gene, and the second, about 5 to 21 million years ago, generated the GPB and GPE genes and that involved a gene that acquired its specific 3' end by homologous recombination through Alu repeats. Numerous variants of GPA and GPB usually detected by abnormal expression of the blood group MNSs antigens are known. An increasing number of these variants have been structurally defined by protein and molecular genetic analyses, and have been shown to result from point mutations, gene deletions, hybrid gene fusion products generated by unequal crossing-over (not at Alu repeats), and microconversion events. The second group of RBC membrane glycophorins includes the minor proteins GPC and GPD both of which carry blood group Gerbich antigens. Protein and nucleic acid analysis indicated that GPD is a truncated form of GPC in its N-terminal region, and that both proteins are produced by a unique gene called GE (Gerbich), which is present as a single copy per haploid genome and is located on chromosome 2q14-q21.(ABSTRACT TRUNCATED AT 400 WORDS)

Stimulation of the Na+,K(+)-ATPase activity of K562 human erythroleukemia cells by triiodothyronine

The effect of triiodothyronine (T3) on Na+,K(+)-ATPase activity of K562 human erythroleukemic cell was studied to understand why the erythrocyte sodium pump activity is decreased in hyperthyroidism. Na+,K(+)-ATPase activity of K562 cell lysates was assayed by measuring the release of inorganic phosphate (Pi) from ATP. Na+,K(+)-ATPase activity of K562 cell grown in the presence of T3 for 48 hours was significantly higher than that of control (0.98 +/- 0.05 mumol Pi h-1 mg protein-1 vs 0.82 +/- 0.10 mumol Pi h-1 mg protein-1, p < 0.05). The Na+,K(+)-ATPase activity could be stimulated in a time- and concentration-dependent manner; maximum stimulatory effect of T3 was seen at a concentration of 10(-7) mol/L. When an inducer [cytosine-beta-D-arabino-furanoside (ARA-C)] was added to the culture medium, the K562 cells showed signs of differentiation and synthesised haemoglobin. At the same time, the Na+,K(+)-ATPase activity remained high. We conclude that T3 stimulates Na+,K(+)-ATPase activity of K562 cells and in the presence of T3 during differentiation, the enzyme activity remains high.

A method for identifying megakaryocytic and erythroid cells by a combined immunocytochemical and cytochemical stain

The effectiveness of immunoperoxidase staining for platelet glycoprotein IIb/IIIa coupled with cytochemical staining for hemoglobin has been evaluated as a dual staining technique for identifying lineage-specific characteristics of the megakaryocytic and erythroid series in cells of the same hemopoietic tissue preparation. A sequence of staining was established which produced a circumferential brown stain around cells of the megakaryocytic series, and a diffuse yellow to orange stain in the cytoplasm of cells of the erythroid series. Each staining reaction possessed a high degree of specificity and sensitivity which enabled the combined stain to provide a convenient means for establishing the megakaryocytic and erythroid nature of individual cells in hematological specimens where classification cannot be achieved with certainty on morphological grounds.

HLA class II induction by interferon-gamma in K562 variant cell line: inhibition by serum lipid

The induction of class II antigen (Ag) by interferon-gamma (IFN-gamma) in variants of the K562 cell line has been examined in this study. Following incubation of K562A cells with IFN-gamma, surface expression of HLA-DR molecules was demonstrated by indirect immunofluorescence, confirmed by immunoblotting, and HLA-DR3 Ag specificity identified. HLA-DP and HLA-DRW52 Ag were co-expressed, but no HLA-DQ expression occurred. A variant of this line, designated K1A, spontaneously developed resistance to IFN-gamma induction of class II Ag, but continued to express class I Ag. In a third K562 variant, designated K562B, no class II gene products could be induced. Northern blot analysis indicated that mRNA levels correlated with surface class I and II Ag expression in all of the K562 cell lines. Resistance to IFN-gamma inducible class II Ag expression in K1A cells did not involve changes in IFN-gamma receptor affinity or number but was shown to be due to an inhibitory effect of serum lipid. These results indicate that cells derived from a common parental line may differ in susceptibility to a regulatory mechanism affecting IFN-gamma inducible class II Ag expression.

S-phase DNA content and aneuploidy of immunophenotypic defined subpopulations in acute myeloid leukemia determined by multi-parameter flow cytometry

One of the major limitations of DNA flow cytometry (FCM) in hematologic malignancies is the lack of information about the proliferation activity of subpopulations of the heterogeneous bone marrow (BM) compartment. We studied the S-phase DNA content of immunophenotypically defined BM subpopulations (CD2+; CD19+; CD2/CD19+; glycophorin-A+; CD14+; CD13+; CD33+ and CD13/CD33+) in 18 patients with acute myeloid leukemia (AML), including three patients with M6 AML. The results were compared with the findings in twelve normal BM aspirates. The measurements were performed using a special protocol for bivariate FCM of DNA content and surface immunofluorescence (s-IF). In patients with AML the proportion of BM cells expressing the myelomonocytic and monocytic markers (M1-M5 AML) or erythroid marker (M6 AML) was expanded. However, in many patients other subpopulations were 4% or higher permitting the calculation of their S-phase DNA. No essential differences in median S-phase DNA percentages of the distinct subpopulations were observed between normal and leukemic bone marrow though the ranges in AML patients were much wider. These data suggest that AML is not characterized by an increased nor a decreased proliferation activity, but rather by a situation of cell growth independent to the normal regulatory mechanisms. Additional information was obtained upon DNA aneuploidy using CD2+ or CD2/CD19+ cells as an intrinsic DNA standard which allowed us to define differences in the DNA index as small as 2% as aneuploid. This approach appeared suitable for detecting small-degree numerical chromosomal aberrencies, as found by cytogenetics, in 4/6 cases.

Essential thrombocythemia: impaired regulation of megakaryocyte progenitors

In this paper, the in vitro growth of bone marrow early (megakaryocyte burst-forming units, BFU-meg) and late (megakaryocyte colony-forming units, CFU-meg) progenitors was evaluated in 18 essential thrombocythemia (ET) patients and 22 normal control subjects. BFU-meg clonality was demonstrated both in normal and ET bone marrows, cultivating these primitive progenitors at limiting dilutions in plasma clot assay: 1 to 7 BFU-meg/2.5 x 10(4) mononuclear non-adherent cells were observed, with a strong correlation in ET [r = 0.955 stimulated by recombinant human granulocyte-macrophage colony-stimulating factor (rhGM-CSF) plus recombinant human interleukin (rhIL) 3], as well as in normal controls (r = 0.969). In order to clearly elucidate the in vitro response of ET megakaryocyte (meg) progenitors to recombinant growth factors, the interference of accessory cells (i.e., monocytes, T lymphocytes, and natural killer cells) and human serum were avoided by performing experiments on CD34+ cells in a serum-free fibrin clot assay. The number of both early and late meg progenitors in ET was significantly increased in response to rhIL-3, rhIL-3 plus rhIL-6, and rhIL-3 plus rhGM-CSF, but not in response to rhGM-CSF alone. Furthermore, both meg progenitors were investigated for their response to rh transfer growth factor (TGF)-beta 1, tested at concentrations from 0.01 to 10 ng/ml. rhTGF-beta 1 was able to inhibit CFU-meg and BFU-meg in a dose-response manner normal, whereas ET CFU-meg appeared less sensitive to the lower doses investigated (p less than 0.05) and ET BFU-meg were slightly reduced in number only at the higher concentrations of rhTGF-beta 1 (p less than 0.01). Our data suggest that the increased thrombopoiesis in ET may depend on an increased sensitivity of meg progenitors to some of the physiological growth factors and to a disrupted sensitivity to at least one negative regulator of megakaryocytopoiesis. Since these abnormalities involve both meg progenitors, this can be considered a demonstration that the neoplastic event hits the most primitive hemopoietic progenitors.

Simultaneous measurement of DNA content and cell-surface immunofluorescence of human bone marrow cells using a single laser flow cytometer

This paper describes the measurement of S phase DNA content in human bone marrow subpopulations using a single laser method for bivariate analysis of DNA content and cell-surface immunofluorescence (s-IF). Low density (less than 1.077 g/ml) bone marrow cells were labeled with a panel of unconjugated monoclonal antibodies (MoAb) for the lymphoid (CD2 + CD19), T-lymphoid (CD2), B-lymphoid (CD19), erythroid (anti-glycophorin-A), myelomonocytic (CD13, CD33; single and as cocktail) and monocytic (CD14) lineages. A fluorescein isothiocyanate (FITC)-conjugated goat anti-mouse label was used as second step. Unfixed, MoAb-labeled cells were incubated for 24 h with a hypotonic propidium iodide solution for DNA staining. Cells were analysed on a single-laser flow cytometer, operating at 488 nm. The effect of the combined staining protocol upon both s-IF and DNA stainability was evaluated. Only a slight decrease (mean: 29.0%) in s-IF intensity was observed after DNA staining. The percentages of immunofluorescent cells in the bone marrow samples of 10 normal individuals before and after DNA staining were essentially unchanged for all the MoAbs used. The DNA histograms of the immunophenotypically defined subpopulations were of excellent quality with a mean coefficient or variation of 1.8%. This procedure allows the assessment of very low levels of S-phase DNA content, as measured in normal low density blood cells of 8 healthy volunteers (mean 0.07%).(ABSTRACT TRUNCATED AT 250 WORDS)

Congenital erythroleukemia: a case report with morphological, immunophenotypic, and cytogenetic findings

We report a lethal case of congenital erythroleukemia presenting on the first day of life with peripheral blast cells and a leukemic infiltrate in the placenta. Although initial bone marrow examination did not fulfill the French-American-British (FAB) cooperative group criteria for acute myelogenous leukemia (AML), including M6, a malignant clone was confirmed by cytogenetic analysis: 49,XX, +8, +19, +21. Evolution to erythroleukemia (M6) occurred over a two-month period. The diagnosis of erythroleukemia was supported by immunophenotyping employing an antibody to glycophorin A. The clinical course was complicated by liver failure of unknown etiology. Comparison to previously reported cases of early childhood erythroleukemia is made.