Suppression of normal human erythropoiesis by gamma interferon in vitro. Role of monocytes and T lymphocytes

Early bone marrow alterations in patients with adenosine deaminase 2 deficiency across disease phenotypes and severities

BACKGROUND

Deficiency of adenosine deaminase 2 (DADA2) is a complex monogenic disease caused by recessive mutations in the ADA2 gene. DADA2 exhibits a broad clinical spectrum encompassing vasculitis, immunodeficiency, and hematologic abnormalities. Yet, the impact of DADA2 on the bone marrow (BM) microenvironment is largely unexplored.

OBJECTIVE

This study comprehensively examined the BM and peripheral blood of pediatric and adult patients with DADA2 presenting with rheumatologic/immunologic symptoms or severe hematologic manifestations.

METHODS

Immunophenotyping of hematopoietic stem cells (HSCs), progenitor cells, and mature cell populations was performed for 18 patients with DADA2. We also conducted a characterization of mesenchymal stromal cells.

RESULTS

Our study revealed a significant decrease in primitive HSCs and progenitor cells, alongside their reduced clonogenic capacity and multilineage differentiation potential. These BM defects were evident in patients with both severe and nonsevere hematologic manifestations, including pediatric patients, demonstrating that BM disruption can emerge silently and early on, even in patients who do not show obvious hematologic symptoms. Beyond stem cells, there was a reduction in mature cell populations in the BM and peripheral blood, affecting myeloid, erythroid, and lymphoid populations. Furthermore, BM mesenchymal stromal cells in patients with DADA2 exhibited reduced clonogenic and proliferation capabilities and were more prone to undergo cellular senescence marked by elevated DNA damage.

CONCLUSIONS

Our exploration into the BM landscape of patients with DADA2 sheds light on the critical hematologic dimension of the disease and emphasizes the importance of vigilant monitoring, even in the case of subclinical presentation.

Anemia May Increase the Overall Risk of Cancer: Findings from a Cohort Study with a 12-Year Follow-up Period in South Korea

BACKGROUND

No previous study has assessed cancer risk in individuals with anemia diagnosed based on hemoglobin levels. Thus, we aimed to investigate whether anemia increases the risk of cancer.

METHODS

Adult individuals who underwent a standardized medical examination during 2002 and 2003 in South Korea were included, and their cancer status was evaluated between January 2004 and December 2015 (12 years) as a primary endpoint. Anemia was defined as serum hemoglobin levels of <12 and <13 g/dL for women and men, respectively.

RESULTS

A total of 454,304 adults were included in the final analysis. Among them, 41,947 (9.2%) and 412,357 (90.8%) individuals constituted the anemia and control groups, respectively. After propensity score matching, a total of 83,886 individuals (41,943 per group) were included in the analysis. Cox regression revealed that the risk of cancer in the anemia group was 3% higher than that in the control group (HR, 1.03; 95% confidence interval, 1.01-1.05; P = 0.023). Specifically, relative to the control group, the anemia group was at an increased risk of gastric (HR, 1.29), esophageal (HR, 1.37), lung (HR, 1.14), and thyroid cancers (HR, 1.14), neoplasms of breast and genital organs (HR, 1.12), and lymphoma or leukemia (HR, 1.63).

CONCLUSIONS

Anemia was independently associated with an increased overall risk of cancer. Further research is required to clarify the associated mechanism.

IMPACT

Anemia was independently associated with an increased overall risk of cancer in the South Korean population.

Interferon-γ exerts dual functions on human erythropoiesis via interferon regulatory factor 1 signal pathway

Hematopoiesis is systematically regulated by microenvironmental factors. The positive and negative factors coordinated together to yield a complicated blood system. Interferon-γ (IFNγ) has been identified as a common cause of various hematopoietic abnormalities, such as aplastic anemia. However, its impact on monolineage development, especially erythropoiesis, has not been fully elucidated from the cellular angle. In this study, we investigated the behavior of IFNγ and found that IFNγ plays dual functions on erythropoiesis; it not only blocks the erythroid lineage commitment but also accelerates the erythroid differentiation process, ultimately leading to the erythropoietic window clearance. IFNγ can even powerfully initiate early differentiation without the existence of erythropoietin (EPO). Interferon regulatory factor 1 (IRF1) was confirmed as the essential downstream effector, and its ectopic overexpression can also have the same effect as that of IFNγ. These results reveal that the IFNγ-IRF1 axis plays a bidirectional role on erythropoiesis, impeding the access to erythroid lineage and driving the coming cells toward the differentiation endpoint. This model may place an innovative implication for IFNγ-IRF1 axis to understand its in-depth mechanism on normal hematopoiesis and abnormal blood disorders, especially aplastic anemia.

Frequency and causes of anemia in Lymphoma patients

Objective:

Purpose of this study was to find out frequency of anemia and its causes in newly diagnosed treatment naive lymphoma patients.

Methods:

We retrospectively studied all lymphoma patients (> 18 years age) diagnosed and treated at Shaukat Khanum Memorial Cancer Hospital and Research Centre, from January 2016 till January 2017. The data was collected from electronic Hospital Information System. Descriptive statistics were done by using summary measures for categorical variables as well as continuous variables.

Results:

Out of a total 408 patients, 272 were males and 136 females. Median age of patients was 33 years (18-76). Hodgkin lymphoma (HL) and diffuse large B cell lymphoma (DLBCL) were the diagnosis in 201 and 134 patients respectively; rest of the patients had low grade lymphomas. Anemia was present in 184 (45%) patients. Anemia of chronic disease was the commonest cause of anemia and was present in 61 (33.1%) patients. Remaining patients had anemia secondary to marrow involvement 50(27.17%); iron deficiency anemia, Vitamin B-12 deficiency anemia and hemolytic anemia were the causes in 7.6, 1.6%, % and 0.54% respectively.

Conclusion:

Anemia is a common feature in newly diagnosed lymphoma patients with anemia of chronic disease as the commonest cause. It is more frequent in patients with higher stages of lymphoma especially when bone marrow is involved by lymphoma. Since anemia is an important adverse prognostic factor for the outcome of lymphoma patients, work up for anemia prior to initiation of chemotherapy should be done in every lymphoma patient in order to help improve the management of these patients.

Stimulation of Interleukin-1 ß Production may be Involved in Unresponsiveness to Erythropoietin Therapy

Recombinant human erythropoietin (rHuEPO) can dramatically improve anemia in dialysis patients, but about 20% of patients show a poor response to this agent. It has been reported that cytokines, including interleukin (IL)-1ß, may inhibit the maturation of erythrocytes. To investigate the mechanisms of unresponsiveness to rHuEPO, we isolated peripheral blood mononuclear cells from 12 patients on continuous ambulatory peritoneal dialysis who were receiving maintenance rHuEPO therapy for renal anemia. Cells were cultured with rHuEPO and IL-1 ß production was assessed. In the six patients who did not respond to rHuEPO therapy, there was a marked increase in IL-1 ß during culture with rHuEPO. In contrast, the addition of rHuEPO to cultures of cells from the six responding patients caused little increase in IL-1 ß, and there was a significant difference between the two groups. Induction of IL-1 ß by rHuEPO may be one cause of persistent anemia in dialysis patients.

CD4 T-cell expression of IFN-γ and IL-17 in pediatric malarial anemia

In Plasmodium falciparum holoendemic transmission regions of western Kenya, life-threatening pediatric malaria manifests primarily as severe malarial anemia (SMA, Hb≤6.0 g/dL with any density parasitemia). To determine the role that CD4+ T-cell-driven inflammatory responses have in the pathogenesis of SMA, peripheral CD4+ T-cell populations and their intracellular production of pro-inflammatory cytokines (IFN-γ and IL-17) were characterized in children aged 12–36 months of age stratified into two groups: non-severe malarial anemia (non-SMA, Hb≥6.0 g/dL, n = 50) and SMA (n = 39). In addition, circulating IFN-γ and IL-17 were measured as part of a Cytokine 25-plex Antibody Bead Kit, Human (BioSource™ International). Children with SMA had higher overall proportions of circulating lymphocytes (P = 0.003) and elevated proportions of lymphocytes expressing IFN-γ (P = 0.014) and comparable IL-17 (P = 0.101). In addition, SMA was characterized by decreased memory-like T-cells (CD4+CD45RA-) expressing IL-17 (P = 0.009) and lower mean fluorescence intensity in memory-like CD4+ T-cells for both IFN-γ (P = 0.063) and IL-17 (P = 0.006). Circulating concentrations of IFN-γ were higher in children with SMA (P = 0.009), while IL-17 levels were comparable between the groups (P = 0.164). Furthermore, circulating levels of IFN-γ were negatively correlated with IL-17 levels in both groups of children (SMA: r = -0.610, P = 0.007; and non-SMA: r = -0.516, P = 0.001), while production of both cytokines by lymphocytes were positively correlated (SMA: r = 0.349, P = 0.037; and non-SMA: r = 0.475, P = 0.001). In addition, this correlation was only maintained by the memory-like CD4+ T cells (r = 0.365, P = 0.002) but not the naïve-like CD4+ T cells. However, circulating levels of IFN-γ were only associated with naïve-like CD4+ T cells producing IFN-γ (r = 0.547, P = 0.028), while circulating levels of IL-17 were not associated with any of the cell populations. Taken together, these results suggest that enhanced severity of malarial anemia is associated with higher overall levels of circulating lymphocytes, enhanced intracellular production of IFN-γ by peripheral lymphocytes and high circulating IFN-γ levels. In addition, the observed inverse relationship between the circulating levels of IFN-γ and IL-17 together with the reduction in the levels of memory-like CD4+ T cells expressing IL-17 in children with SMA may suggest possible relocation of these cells in the deeper tissues for their pathological effect.

IFN-γ-mediated hematopoietic cell destruction in murine models of immune-mediated bone marrow failure

Interferon gamma (IFN-γ) has been reported to have both negative and positive activity on hematopoietic cells, adding complexity to the interpretation of its pleiotropic functions. We examined the effects of IFN-γ on murine hematopoietic stem cells (HSCs) and progenitors in vitro and in vivo by using mouse models. IFN-γ treatment expanded bone marrow (BM) c-Kit(+)Sca1(+)Lin(-) (KSL) cell number but reduced BM KLCD150(+) and KLCD150(+)CD48(-) cells. IFN-γ-expanded KSL cells engrafted poorly when tested by competitive repopulation in vivo. KSL, KLCD150(+), and KLCD150(+)CD48(-) cells from IFN-γ-treated animals all showed significant upregulation in Fas expression. When cocultured with activated T cells in vitro, KSL and KLCD150(+) cells from IFN-γ-treated donors showed increased apoptosis relative to those from untreated animals, and infusion of activated CD8 T cells into IFN-γ-injected animals in vivo led to partial elimination of KSL cells. Exposure of BM cells or KSL cells to IFN-γ increased expression of Fas, caspases, and related proapoptotic genes and decreased expression of Ets-1 and other hematopoietic genes. In mouse models of BM failure, mice genetically deficient in IFN-γ receptor expression showed attenuation of immune-mediated marrow destruction, whereas effector lymphocytes from IFN-γ-deficient donors were much less potent in initiating BM damage. We conclude that the activity of IFN-γ on murine hematopoiesis is context dependent. IFN-γ-augmented apoptotic gene expression facilitates destruction of HSCs and progenitors in the presence of activated cytotoxic T cells, as occurs in human BM failure.

The role of adipocytes in the modulation of iron metabolism in obesity

A tight relationship between iron deficiency and obesity is known to exist. The chronic low-grade inflammation that characterizes obesity enhances hepcidin production, the principal regulator of iron availability. Adipose tissue is known to secret interleukin-6 and leptin that triggers hepcidin production. It was found that adipose tissue also expresses hepcidin and hemojuvelin, a regulator of hepcidin production. These recent findings suggest that adipose tissue may have an important role in erythropoiesis particularly on obesity that is still poorly clarified. This paper discusses these findings and how they can modulate erythropoiesis.

Biological rationale and clinical use of interferon in the classical BCR-ABL-negative myeloproliferative neoplasms

Because of its antiapoptotic, antiproliferative, and immunomodulatory properties, interferon (IFN) has been broadly used as an antiviral and antineoplastic agent. These properties are particularly suitable for the treatment of the classical BCR-ABL-negative myeloproliferative neoplasms (MPN), including essential thrombocytosis (ET), polycythemia vera (PV), and myelofibrosis (MF). In the MPN, IFN has been shown to suppress megakaryopoiesis, inhibit erythroid colony-forming cells, suppress bone marrow fibroblast progenitors, induce cytogenetic remission, and reduce the JAK2 V617F allele burden, sometimes completely. Although efficacy has long been demonstrated in the MPN, toxicities were frequent with recombinant IFN, tempering enthusiasm. However, with pegylated-IFN, because of less toxicity, there has been renewed interest, and recent studies in the MPN have shown hematologic and molecular response or remission in ET and PV; a smaller study in early MF has shown IFN's potential to retard fibrosis. The role of IFN in the treatment of MPN is being re-evaluated on the basis of these studies, and will be better defined as results return from an ongoing international study.

Leishmania donovani infection induces anemia in hamsters by differentially altering erythropoiesis in bone marrow and spleen

Leishmania donovani is a parasite that causes visceral leishmaniasis by infecting and replicating in macrophages of the bone marrow, spleen, and liver. Severe anemia and leucopenia is associated with the disease. Although immune defense mechanisms against the parasite have been studied, we have a limited understanding of how L. donovani alters hematopoiesis. In this study, we used Syrian golden hamsters to investigate effects of L. donovani infection on erythropoiesis. Infection resulted in severe anemia and leucopenia by 8 weeks post-infection. Anemia was associated with increased levels of serum erythropoietin, which indicates the hamsters respond to the anemia by producing erythropoietin. We found that infection also increased numbers of BFU-E and CFU-E progenitor populations in the spleen and bone marrow and differentially altered erythroid gene expression in these organs. In the bone marrow, the mRNA expression of erythroid differentiation genes (α-globin, β-globin, ALAS2) were inhibited by 50%, but mRNA levels of erythroid receptor (c-kit, EpoR) and transcription factors (GATA1, GATA2, FOG1) were not affected by the infection. This suggests that infection has a negative effect on differentiation of erythroblasts. In the spleen, erythroid gene expression was enhanced by infection, indicating that the anemia activates a stress erythropoiesis response in the spleen. Analysis of cytokine mRNA levels in spleen and bone marrow found that IFN-γ mRNA is highly increased by L. donovani infection. Expression of the IFN-γ inducible cytokine, TNF-related apoptosis-inducing ligand (TRAIL), was also up-regulated. Since TRAIL induces erythroblasts apoptosis, apoptosis of bone marrow erythroblasts from infected hamsters was examined by flow cytometry. Percentage of erythroblasts that were apoptotic was significantly increased by L. donovani infection. Together, our results suggest that L. donovani infection inhibits erythropoiesis in the bone marrow by cytokine-mediated apoptosis of erythroblasts.

Inhibitory effect of interferon-beta on mouse spleen-derived mast cells

Preparations of murine recombinant interferon (Mu-rIFN)-alpha, -beta and -gamma were assessed for their influence on in vitro growth of mast cells from normal mouse spleen cells (Sp C). Mast cell growth was inhibited by Mu-rIFNs when Sp C were exposed throughout the entire culture period to Mu-rIFNs. The most potent inhibitor of mast cell growth was Mu-rIFN-gamma, followed by Mu-rIFN-beta; Mu-rlFN-alpha had little effect. When added to IC-2 cells, clonal mast cell progenitor, both Mu-rlFN-beta and -gamma), significantly inhibited proliferative response of the target cells. The suppressive effect of Mu-rIFNs on IC-2 cells was selectively abolished by monoclonal antibodies against Mu-rIFN-beta and -gamma.

Stress induced experimental colitis

Stress induces chemical changes in the central nervous system which alters the biochemistry and physiology of the digestive tract. The present study determines arachidonic acid oxidation and damage in the colon following stress. Ten rats were stressed by the cold-restraint method; ten were controls. Stress induced 0.5 ± 0.7 (S.D.) mucosal erosions whereas controls had none. Subepithelial hemorrhage and erosions occurred only in the proximal two-thirds of the colon. Prostaglandin E₂ synthesis was increased after stress compared to the control (381 ± 130 vs. 1610 ± 372 ng/g/min). Leukotriene C₄ synthesis also increased after stress (4217 ± 994 vs. 11300 ± 1662 ng/g/min). Synthesis of prostaglandin E₂ increased (r = 0.9381) with leukotriene C₄. The response of the colon to stress is less severe than that in the stomach and may be related to regional regulation of prostaglandin and leukotriene synthesis.

Erythroid disturbances before and after treatment of Portuguese psoriasis vulgaris patients: a cross-sectional and longitudinal study

BACKGROUND

A few studies in psoriasis vulgaris patients have reported changes suggesting red blood cell (RBC) damage is linked to neutrophil activation, oxidative stress, and psoriasis worsening.

OBJECTIVE

The aim of this study was to evaluate erythroid disturbances in Portuguese psoriasis vulgaris patients, before, during, and after treatment.

METHODS

A cross-sectional study (n = 73 patients vs 40 healthy control subjects) followed by a longitudinal study (n = 47 patients) was performed, with assessments before, and at 3, 6, and 12 weeks of therapy (10 patients started topical treatment, 17 narrow-band UVB, and 20 photochemotherapy [psoralen plus UVA; PUVA]). Evaluations included hematologic data, total bilirubin levels, membrane-bound hemoglobin (MBH), membrane protein band 3 profile, total plasma antioxidant status (TAS), lipid peroxidation (thiobarbituric acid [TBA] assay), elastase, lactoferrin, and C-reactive protein (CRP).

RESULTS

Before treatment, patients presented with higher leukocyte/neutrophil and reticulocyte counts, elastase, lactoferrin, TBA, TBA/TAS, reticulocyte production index, total bilirubin and MBH values, lower RBC and hematocrit, higher percentages of high-molecular-weight aggregates, and lower percentages of band 3 monomer. After treatment, we observed a reversal in most of the parameters. However, patients still presented with values suggestive of accelerated RBC damage, removal, and production, as most of the parameters were still higher than those in the control group; the same occurred with CRP.

CONCLUSION

Our data suggest that psoriasis vulgaris triggers an inflammatory response, with release of acute-phase reactants, reactive oxygen species, cationic proteins, and proteases, leading to enhanced RBC damage/aging and, ultimately, to enhanced RBC removal. These assumptions were strengthened by the observation that, with treatment, all of these changes were reversed, the inflammation was reduced, the production of reticulocytes was increased, and the RBCs presented changes usually observed in younger/less damaged RBCs. These erythroid changes were enhanced with PUVA therapy, probably due to the more pronounced clearing of the lesions, as suggested by Psoriasis Area and Severity Index (PASI) scores. Finally, after treatment, a residual inflammation still persisted that might contribute to the observed erythroid disturbances.

Interferon gamma has dual potential in inhibiting or promoting survival and growth of hematopoietic progenitors: interactions with stromal cell-derived factor 1

We explored the possibility that interferon gamma (IFN-gamma) has bidirectional functions in the survival and growth of hematopoietic progenitors, especially with regard to interactions with stromal cell-derived factor 1 (SDF-1). IFN-gamma partially rescued normal bone marrow CD34+ cells and colony-forming cells from apoptosis induced by serum and hematopoietic growth factor (HGF) deprivation, and SDF-1 further enhanced cell survival. Short-term IFN-gamma treatment of CD34+ cells in the absence of serum and HGFs enhanced the clonal growth of the cells in synergy with SDF-1. In contrast, IFN-gamma inhibited the clonal growth of hematopoietic progenitor cells in a standard methylcellulose clonogenic assay and inhibited the HGF-mediated survival of normal CD34+ cells. The addition of SDF-1 did not alter these outcomes. IFN-gamma did not enhance SDF-1-induced activation of PI3K/Akt or up-regulate the expression of CXCR4 or its function in bone marrow CD34+ cells. IFN-gamma up-regulated Socs1 messenger RNA expression in normal CD34+ cells, which was further enhanced with the addition of HGFs. These results indicate that IFN-gamma, partly in concert with SDF-1, exerts dual effects on the survival and growth of hematopoietic progenitor cells; the effects of IFN-gamma on hematopoietic progenitor cells can differ, depending on the particular in vitro experimental conditions, especially the presence of HGFs.

Interferon gamma has dual potential in inhibiting or promoting survival and growth of hematopoietic progenitors: interactions with stromal cell-derived factor 1

We explored the possibility that interferon gamma (IFN-gamma) has bidirectional functions in the survival and growth of hematopoietic progenitors, especially with regard to interactions with stromal cell-derived factor 1 (SDF-1). IFN-gamma partially rescued normal bone marrow CD34+ cells and colony-forming cells from apoptosis induced by serum and hematopoietic growth factor (HGF) deprivation, and SDF-1 further enhanced cell survival. Short-term IFN-gamma treatment of CD34+ cells in the absence of serum and HGFs enhanced the clonal growth of the cells in synergy with SDF-1. In contrast, IFN-gamma inhibited the clonal growth of hematopoietic progenitor cells in a standard methylcellulose clonogenic assay and inhibited the HGF-mediated survival of normal CD34+ cells. The addition of SDF-1 did not alter these outcomes. IFN-gamma did not enhance SDF-1-induced activation of PI3K/Akt or up-regulate the expression of CXCR4 or its function in bone marrow CD34+ cells. IFN-gamma up-regulated Socs1 messenger RNA expression in normal CD34+ cells, which was further enhanced with the addition of HGFs. These results indicate that IFN-gamma, partly in concert with SDF-1, exerts dual effects on the survival and growth of hematopoietic progenitor cells; the effects of IFN-gamma on hematopoietic progenitor cells can differ, depending on the particular in vitro experimental conditions, especially the presence of HGFs.

Hemophagocytic lymphohistiocytosis complicating influenza A infection

During the influenza A (H3N2) season of 2003-2004, several influenza-related complications and deaths were reported in children. Hemophagocytic lymphohistiocytosis complicating influenza A infection is very rare. We report a 3-year-old girl who presented with severe pneumonia and hemophagocytic lymphohistiocytosis associated with influenza A infection. Clinicians should be aware of hemophagocytic syndrome as a serious complication of influenza A infection.

Chemokine expression in human erythroid leukemia cell line AS-E2: macrophage inflammatory protein-3alpha/CCL20 is induced by inflammatory cytokines

OBJECTIVE

Normal and malignant hematopoietic cells are shown to express and secrete various cytokines and chemokines, some of which are believed to play an important role in normal and abnormal hematopoiesis in an autocrine/paracrine manner. To explore the possibility of a cytokine/chemokine network participating in the pathophysiology of anemic disorders, we evaluated the ability of inflammatory cytokines to induce chemokine expression using erythroid progenitor cells.

METHODS

Erythropoietin-dependent human leukemia cell line AS-E2 was used as a model of erythroid colony-forming unit (CFU-E) cells. The expression of mRNA of 8 chemokines was examined using RT-PCR, before and after TNF-alpha, IFN-gamma, and IL-1beta stimulation. For MIP-3alpha, the promoter activity was analyzed by luciferase assay and secretion was confirmed by ELISA. The expression of CCR6, the specific receptor for MIP-3alpha, was analyzed by RT-PCR and flow cytometry.

RESULTS

Unstimulated AS-E2 cells constitutively expressed transcripts for MCP-4, IP-10, PF-4, IL-8, and MIP-3alpha. Stimulation with TNF-alpha, IFN-gamma, and IL-1beta upregulated MIP-3alpha mRNA expression and induced its protein secretion. Luciferase assay revealed that these cytokines could upregulate promoter activity of the MIP-3alpha gene, possibly through the NF-kappaB pathway. CCR6 mRNA was detected and its intracellular expression was confirmed.

CONCLUSION

These data suggest that inflammatory cytokine-stimulated erythroid progenitors secrete MIP-3alpha, which may function in an autocrine/paracrine manner. Furthermore, the existence of intracellular CCR6 suggests the involvement in cytokine signaling of a MIP-3alpha-dependent internal autocrine mechanism. These mechanisms may play a role in pathophysiology of anemic disorders, such as secondary anemia and bone marrow failure syndromes.

Direct and indirect effects of androgens on survival of hematopoietic progenitor cells in vitro

Androgens remain a common treatment for certain type of anemia, based upon its myelostimulating effects; however, it has not been established whether androgens affect apoptosis of hematopoietic progenitor cells (HPCs). We investigated the effects of the androgens, such as testosterone, 5beta-dihydrotestosterone (5-DHT), and oxymetholone, on apoptosis of normal hematopoietic progenitor cells in vitro. Androgens did not rescue normal bone marrow (BM) CD34+ cells and colony-forming cells (CFCs), other than mature erythroid CFCs, from apoptosis induced by serum- and growth factor deprivation. Oxymetholone did not affect growth factor-mediated survival of normal CD34+ cells or its inhibition by interferon-gamma (IFN-gamma). In a standard methylcellulose clonogenic assay, low concentrations of oxymetholone and 5-DHT stimulated the clonal growth of colony-forming unit (CFU)-erythroid, but did not affect growth of CFU-granulocyte/macrophage or burst-forming unit-erythroid. Oxymetholone and 5-DHT stimulated the production of stem cell factor in normal bone marrow stromal cells (BMSCs) via transcriptional regulation. In agreement with this, oxymetholone-treated BMSCs better supported the survival of HPCs. These data indicate that survival-enhancing or growth-stimulatory effects of androgens on hematopoietic progenitor cells are minimal and mostly restricted to mature erythroid progenitors, and its myelostimulating effects could be attributed, at least in part, to the stimulation of production of hematopoietic growth factors in BMSCs.

A novel role for STAT1 in regulating murine erythropoiesis: deletion of STAT1 results in overall reduction of erythroid progenitors and alters their distribution

Erythropoietin (EPO) activates many distinct signal transduction cascades on engagement of its receptor. Deletion of the EPO, EPO receptor (EPO-R), or JAK2 genes in mice results in embryonic lethality due to a fatal anemia. EPO activates signal transducer and activator of transcription 1 (STAT1), STAT3, and STAT5a/b transcription factors in erythroid cell lines. Studies have focused on STAT5 as the primary target of EPO-dependent JAK2 activation. However, STAT5a/b(-/-) mice are viable, displaying a nonfatal anemia during embryogenesis, and delayed differentiation in adult erythropoiesis. Importantly, EPO-R cytoplasmic tyrosines are dispensable for viability in vivo. Interestingly, no cytoplasmic tyrosines are required for phosphorylation of STAT1. This led us to examine whether STAT1-deficient mice have altered erythropoiesis. A shift in erythropoiesis was observed in STAT1(-/-) mice, with reduced bone marrow-derived erythroid colony-forming units (CFU-Es) and a compensatory increase in splenic burst-forming units (BFU-Es) and CFU-Es. Both types of splenic-derived cells displayed EPO hyperresponsiveness. A 1.6-fold reduction in total CFU-Es was observed in STAT1-deficient mice, whereas total BFU-Es were comparable. Flow cytometry of STAT1-deficient erythroid cells revealed a less differentiated phenotype, associated with increased apoptosis of early erythroblasts. STAT1-deficient erythroblasts from phenylhydrazine-primed mice displayed enhanced phosphorylation of STAT5a/b, Erk1/2, and protein kinase B (PKB)/Akt. These results illustrate that STAT1 plays an important role in the regulation of erythropoiesis.

Suboptimal erythropoietic response to hypoxemia in idiopathic pulmonary fibrosis

BACKGROUND AND STUDY OBJECTIVES

Idiopathic pulmonary fibrosis (IPF) is a chronic inflammatory process characterized by severe derangement of gas exchange in the advanced stages of disease. However, erythrocytosis is infrequent in IPF. The aim of this study was to investigate the potential relation between the blunted erythropoietic response and the chronic inflammation.

SUBJECTS

Nine patients (6 men and 3 women) with IPF and profound hypoxemia (PO(2) < 65 mm Hg) and 34 sex- and age-matched healthy volunteers participated in the study.

METHODS

We evaluated the hematologic parameters, serum erythropoietin, tumor necrosis factor (TNF)-alpha, interleukin (IL)-6, and IL-8 levels. We also studied the development of burst-forming unit-erythroid (BFU-E)-derived colonies in semisolid methylcellulose cultures in blood samples from all patients.

RESULTS

Hemoglobin and serum erythropoietin levels were almost comparable between the two studied groups. On the contrary, serum TNF-alpha, IL-6, and IL-8 values were significantly higher in patients with IPF (p < 0.05, p < 0.01, and p < 0.001, respectively). IPF sera induced a significant growth inhibition of erythroid bursts arising from mononuclear cells of either patients or control subjects compared with heat-inactivated AB serum (p < 0.05 and p < 0.01, respectively). Moreover, there was an apparent increment in the number of BFU-E colonies when patients' mononuclear cells were cultured in comparison with those of healthy subjects (p < 0.05).

CONCLUSIONS

Our findings suggest that in IPF there is an increased number of primitive erythroid progenitors, which fail to proliferate and differentiate in vivo, suggesting a kind of ineffective erythropoiesis. As a consequence, hemoglobin levels do not rise in proportion to the severity of hypoxemia. Cytokines released from alveolar macrophages seem to have not only local but also systemic effects, since the serum of these patients directly suppressed erythropoiesis; however, the suboptimal erythropoietic response to hypoxia cannot be entirely attributed to this suppression. It is possible that several other factors interfere, synergistically or additively.

Stem cell factor increases the expression of FLIP that inhibits IFNgamma -induced apoptosis in human erythroid progenitor cells

Interferon gamma (IFNgamma) acts on human erythroid colony-forming cells (ECFCs) to up-regulate Fas, without a demonstrable change of Fas ligand (FasL) or Fas-associated DD-containing protein (FADD) expression and activates caspase-8 plus caspase-3, which produce apoptosis. Our previous data showed that stem cell factor (SCF) reduced the inhibitory effect of IFNgamma on human ECFCs when both factors were present in the cultures. However, the mechanism by which SCF prevents IFNgamma-induced apoptosis in ECFCs is unclear. In this study we used highly purified human ECFCs to investigate the mechanism of the effect of SCF on IFNgamma-induced apoptosis. Because the binding of FasL to Fas is the first step of the apoptosis cascade and IFNgamma strongly up-regulates Fas expression, we added FasL (50 ng/mL) to the cultures with IFNgamma to accentuate the IFNgamma-induced activation of caspase-8 and caspase-3 plus subsequent apoptosis. SCF (100 ng/mL) clearly inhibited the activation of caspase-8 and caspase-3 induced by IFNgamma and/or FasL, and it also reduced apoptosis as measured by the terminal dUTP nick-end labeling (TUNEL) assay. SCF did not decrease the surface expression of Fas on the ECFCs. FADD-like interleukin 1 beta (IL-1beta)-converting enzyme (FLICE)-inhibitory protein (FLIP) has been reported to interact with FADD and/or caspase-8 at the death-inducing signaling complex (DISC) level following Fas stimulation and acts as a dominant-negative caspase-8. SCF increased FLIP mRNA and protein expression, concomitant with reduced apoptosis, whereas IFNgamma and/or FasL did not change FLIP expression. Reduction of FLIP expression with antisense oligonucleotides decreased the capacity of SCF to inhibit IFNgamma-induced apoptosis, demonstrating a definite role for FLIP in the SCF-induced protection of ECFCs from IFNgamma-initiated apoptosis.

Hypoplastic myelodysplastic syndromes can be distinguished from acquired aplastic anaemia by bone marrow stem cell expression of the tumour necrosis factor receptor

It is often difficult to distinguish hypoplastic myelodysplastic syndrome (h-MDS) from acquired aplastic anaemia (AA), because of the considerable clinical, cytological and histological similarities between these two disorders. The distinction between AA and h-MDS is important because there is a higher risk of progression to acute leukaemia in patients with h-MDS compared with AA. Recent studies suggest that tumour necrosis factor-alpha (TNF-alpha) plays an important role in the development of AA. In order to determine the potential importance of TNF-alpha in the differential diagnosis of hypoplastic bone marrow (BM) disorders, we examined whether analysis ofTNF-receptor expression could be used as a tool to differentiate AA from h-MDS. Flow cytometric analysis revealed that BM stem cells (CD34+) from AA patients have markedly greater TNF receptor (R) 1 and TNFR2 expression than those from patients with MDS and h-MDS. We suggest that the BM stem cells with a high expression of TNFR in patients with AA may be potently sensitive to TNF-alpha stimulation of differentiation. Thus, we propose that quantification of TNFR expression in BM stem cellsmay be a useful method to distinguish AA from h-MDS.

Temporal effects of gamma interferon deficiency on the course of Friend retrovirus infection in mice

The current studies demonstrate complex and seemingly contradictory effects by gamma interferon (IFN-gamma) on Friend virus (FV) infection. Both temporal and tissue-specific effects were observed. During the first week of infection, IFN-gamma-deficiency caused increased levels of FV infection in multiple tissues. Surprisingly, however, by 2 weeks postinfection, IFN-gamma-deficient mice had significantly lower levels of infection in both the spleen and bone marrow compared to wild-type mice. The rapid reduction of virus in the IFN-gamma-deficient mice correlated with a more rapid virus-neutralizing antibody response than was observed in the wild-type mice. Furthermore, the virus-neutralizing antibody response in wild-type mice could be accelerated by ablation of their IFN-gamma response. Although the IFN-gamma-deficient mice developed an accelerated virus-neutralizing antibody response, they did not class-switch to immunoglobulin G class immunoglobulins nor could they maintain long-term virus-neutralizing antibody titers. Eventually, all of the IFN-gamma-deficient mice failed to keep persistent virus in check and developed fatal FV-induced erythroleukemia.

Novel erythropoiesis stimulating protein (darbepoetin alfa) alleviates anemia associated with chronic inflammatory disease in a rodent model

OBJECTIVE

We developed a rodent model of noninfectious systemic inflammation to examine the pathogenesis of the associated anemia of chronic disorders (ACD), to evaluate the similarity of this ACD model to human ACD, and to evaluate the potential efficacy of novel erythropoiesis stimulating protein (darbepoetin alfa) as an ACD therapy.

METHODS

Lewis rats were immunized with peptidoglycan-polysaccharide polymers (PG-APS), the chronic inflammation and associated ACD were characterized, and the effects of darbepoetin alfa treatment on complete blood counts (CBC), red blood cell (RBC) indices, and iron metabolism were analyzed weekly.

RESULTS

Acutely inflamed rats had reduced peripheral blood (PB) RBC counts and hemoglobin (Hb) concentrations and increased reticulocyte counts. PB RBC numbers normalized during chronic inflammation, but RBC remained hypochromic and microcytic. Consequently, the rats remained chronically anemic. Anemic rats had fluctuating serum erythropoietin (EPO) concentrations, but mean EPO concentrations never varied significantly from baseline control levels. Histology of anemic rat spleen sections revealed reticuloendothelial siderosis. Total serum iron concentrations were chronically low. Peritoneal exudate cells (PEC) isolated from anemic rats and stimulated with PG-APS in vitro produced more interleukin (IL)-1alpha and interferon (IFN)-gamma, and significantly more tumor necrosis factor (TNF)-alpha and IL-10 than control cultures. Darbepoetin alfa restored Hb concentrations to baseline levels within 2 to 7 weeks, depending on dosage. A refined treatment strategy restored Hb to baseline and maintained those levels with reduced dosing.

CONCLUSION

ACD in this rodent model closely replicates human ACD. Darbepoetin alfa treatment reversed ACD in this model by increasing RBC production and RBC hemoglobinization while reducing siderosis and hypoferremia.

Blood and bone marrow changes in malaria

A variety of abnormalities in the number, morphology and function of blood and bone marrow cells may be found in Plasmodium falciparum and P. vivax malaria. In a non-immune individual, the nature of such abnormalities depends on the time after infection. In others it is determined by the pattern and intensity of malaria transmission in the area and the extent of host immunity. Severe anaemia may occur in children with chronic falciparum malaria and low parasitaemia as well as in patients with complicated acute falciparum malaria with high parasitaemia. However, the mechanisms underlying the anaemia in these two situations appear to be different. The possible roles of parasite products, T-cell-derived cytokines produced in response to the infection, macrophage activation and hyperplasia, macrophage-derived factors such as tumour necrosis factor-alpha, and macrophage dysfunction in the pathogenesis of the haematological abnormalities are discussed.

The anaemia of infection

Anaemia is a common finding in infected individuals, and in many cases is an indicator of disease activity and/or duration. The term 'anaemia of infection' refers to a specific syndrome related to the more broadly defined 'anaemia of chronic disease'. In this syndrome, cytokines produced as part of the host response to infection induce anaemia by well-defined pathophysiological mechanisms. In this chapter, the diagnosis, significance, pathophysiology and treatment of the anaemia of infection will be reviewed. Other mechanisms which can produce anaemia in infected individuals will also be reviewed.

Stimulation of tumour necrosis factor-alpha production by recombinant human erythropoietin may contribute to failure of therapy

Although the mechanism of unresponsiveness to recombinant human erythropoietin therapy in dialysis patients has been studied extensively in recent years, many aspects remain unclear. We previously found that administration of erythropoietin induces interleukin-1beta, a cytokine that inhibits erythropoiesis. The present study investigated the involvement of tumour necrosis factor-alpha, another cytokine which inhibits erythropoiesis. Peripheral blood mononuclear cells were obtained from 18 patients on continuous ambulatory peritoneal dialysis, who were being treated with erythropoietin for renal anaemia, and were cultured with various concentrations of erythropoietin (0, 1, 5, 10, and 50 U/ml). Then the tumour necrosis factor-alpha level in the culture supernatant was assayed. The 18 patients were divided into four groups on the basis of the haematocrit after treatment: group A (n = 3), <23.0%; group B (n = 5), 23.0-24.9%; group C (n = 7), 25.0-26.9%; and group D (n = 3), > or =27.0%. In group A, the tumour necrosis factor-alpha level in the culture supernatant was increased by incubation with erythropoietin, while it was not increased in other groups. The tumour necrosis factor-alpha level was significantly higher in group A than in the other groups at erythropoietin concentrations of 5 U/ml. These results suggested that induction of tumour necrosis factor-alpha is one of the reasons for unresponsiveness to recombinant human erythropoietin.

Anaemia in systemic lupus erythematosus: aetiological profile and the role of erythropoietin

OBJECTIVE

To study the prevalence of different causes of anaemia in patients with systemic lupus erythematosus (SLE) and their associations with immunological and clinical parameters and to evaluate the contribution of erythropoietin (Epo) and anti-erythropoietin (anti-Epo) autoantibodies to the development of SLE anaemia.

METHODS

132 SLE patients with anaemia (defined as haemoglobin of 12 g/dl or less for women and 13.5 g/dl or less for men) from among a total of 345 consecutive SLE patients were prospectively enrolled into the study. Standard haematological and immunological tests were performed and serum Epo and anti-Epo antibodies were assayed.

RESULTS

The identified causes were anaemia of chronic disease (ACD) n=49 (37.1%), iron deficiency anaemia (IDA) n = 47 (35.6%), autoimmune haemolytic anaemia (AHA) n = 19 (14.4%) and other causes n = 17 (12.9%). There was significant heterogeneity in the severity of anaemia between the four groups (p<0.01) with AHA cases being on average more severe. The proportion of patients with anticardiolipin antibodies, low complement levels and anti-dsDNA differed significantly among the four groups; these markers were particularly common in patients with AHA, and uncommon in patients with IDA. Twenty one of 100 tested patients had anti-Epo antibodies. Such antibodies were seen practically only in patients with ACD (odds ratio 3.1, p = 0.041) and in patients with high lupus activity (ECLAM) scores (odds ratio 1.27 per point, p = 0.055). Epo response was inadequate in 42.4% and 41.2% of patients with ACD and AHA, respectively.

CONCLUSIONS

Anaemia in SLE usually takes the form of ACD and IDA, however autoimmune haemolysis is not uncommon. SLE patients with different causes of anaemia differ in regard to several immunological parameters. Epo response is blunted in anaemic SLE patients, particularly those with ACD and AHA.

Pure red cell aplasia in a patient with chronic granulocytic leukaemia treated with interferon-alpha

Interferon-alpha has been shown to improve survival in patients with chronic granulocytic leukaemia, therefore it is increasingly becoming part of the standard treatment of this condition. Interferon has a wide variety of side-effects. Pure red cell aplasia has been reported in a few cases of chronic granulocytic leukaemia but this usually heralds the onset of the transformation to the acute phase. This paper reports a possible, and not previously reported, side-effect of interferon-alpha in a patient with chronic granulocytic leukaemia.

Interferon γ Induces Upregulation and Activation of Caspases 1, 3, and 8 to Produce Apoptosis in Human Erythroid Progenitor Cells

Interferon γ (IFNγ) induces apoptosis in purified human erythroid colony-forming cells (ECFC) and inhibits cell growth. Fas (APO-1; CD95) and Fas ligand (FasL) mediate apoptosis induced by IFNγ, because Fas is significantly upregulated by IFNγ, whereas Fas ligand is constitutively present in the ECFC and neutralization of FasL greatly reduces the apoptosis. Because conversion of caspases from their dormant proenzyme forms to active enzymes has a critical role in transducing a cascade leading to apoptosis, we performed further studies of the expression and activation of caspases in normal human and IFNγ-treated day-6 ECFC to better understand the mechanism of IFNγ action in producing this cell death. RNase protection assays showed that the caspase-1, -2, -6, -8, and -9 mRNAs were upregulated by IFNγ, whereas the caspase-5 and -7 mRNAs were not increased. Western blots showed that FLICE/caspase-8 was upregulated and activated by 24 hours of incubation with IFNγ. FADD was not similarly altered by incubation with IFNγ. Western blots of ICE/caspase-1, which might be required for amplification of the initial FLICE activation signal, showed that pro-ICE expression significantly increased after treatment with IFNγ for 24 hours and cleavage of pro-ICE also increased. CPP32/apopain/caspase-3, responsible for the proteolytic cleavage of poly (ADP) ribose polymerase (PARP), was also studied and treatment of ECFC with IFNγ resulted in an increased concentration of caspase-3 by 24 hours and a clear induction of enzyme activation by 48 hours, which was identified by the appearance of its p17-kD peptide fragment. The cleavage of PARP was demonstrated by an obvious increase of the 89-kD PARP cleavage product, which was observed at almost the same time as caspase-3 activation in the IFNγ-treated cells, whereas untreated ECFC showed little change. Peptide inhibitors of the caspase proteins, DEVD-fmk, DEVD-cho, YVAD-cho, and IETD-fmk, were incubated with the ECFC to obtain further evidence for the involvement of caspases in IFNγ-induced apoptosis. The activation of FLICE/caspase-8 and CPP32/caspase-3 and cleavage of PARP clearly were inhibited, but the reduction of cell growth due to apoptosis, induced by IFNγ, was only partially blocked by the presence of the inhibitors. These results indicate that IFNγ acts on ECFC not only to upregulate Fas, but also to selectively upregulate caspases-1, -3, and -8, which are activated and produce apoptosis, whereas the concentrations of FasL and FADD are not demonstrably changed.

Serum levels of tumor necrosis factor-alpha, interleukin-1, and interferon-gamma in beta(o)-thalassemia/HbE and their clinical significance

Serum levels of tumor necrosis factor-alpha (TNF-alpha), interleukin-1alpha (IL-1alpha), and interferon-gamma (IFN-gamma) were estimated by conventional ELISA kits in 60, 42, and 58 Thai patients, respectively, with beta(o)-thalassemia HbE and found to be above the normal range in 13%, 21%, and 33% of the patients, respectively. Using high-sensitivity ELISA systems, an additional 10 beta(o)-thal/HbE patients were compared with 9 controls for concentrations of circulating TNF-alpha and IL-1beta, and 9 and 5 patients, respectively, but only 1 and none of the controls, respectively, showed values above the normal ranges. In patients with abnormally high IFN-gamma levels, basal hemoglobin values were significantly lower than in those with normal levels of the cytokine (mean +/- SEM: 6.03+/-0.24 vs. 7.08+/-0.18, p < 0.05), although circulating concentrations of soluble transferrin receptors (sTrF) and absolute reticulocyte counts were similar in the two groups. Patients with raised or normal levels of TNF-alpha, IL-1alpha, or IL-1beta had similar basal hemoglobin values. In a phagocytosis assay, monocytes of patients with raised serum levels of IFN-gamma showed significantly more attached or ingested IgG-coated red cells than those of patients with normal concentrations of the cytokine (mean +/- SEM: 192+/-22 vs. 140+/-14 per 100 monocytes, p < 0.05). Moreover, in 3 of 4 of the former patients, the number of attached or ingested IgG-coated red cells per 100 monocytes was above the 95% reference limit for the latter patients. The results suggest that IFN-gamma aggravates the anemia of beta(o)-thal/HbE by activating mononuclear phagocytes for destruction of red cells but not by inhibiting erythropoiesis. The elevated serum levels of TNF-alpha and IL-1 could contribute to complications of the disease, such as cachexia and thromboembolic phenomena.

Frequency and significance of anemia in non-Hodgkin's lymphoma patients

OBJECTIVES

Retrospective evaluation of anemia frequency and its prognostic value in patients with different subtypes of non-Hodgkin's lymphoma and comparison with other clinical characteristics.

PATIENTS AND METHODS

Anemia was defined as a hemoglobin value less than or equal to 12 g/dl for all men and women over 50 years of age, and less than or equal to 11 g/dl for women under 50 years of age. The study included 1077 adult lymphoma patients treated between 1980 and 1995 with the following histologic subtypes: 127 patients with small lymphocytic or lymphoplasmacytoid, 62 with marginal zone, 50 with mantle-cell, 208 with follicular, 104 with T-cell lymphoma, 426 with diffuse large-cell and, finally, 73 patients with other high-grade lymphomas.

RESULTS

Anemia was present in 341 patients (32%). It was an adverse prognostic factor (P < 0.0001) for overall survival (OS) and progression-free survival (PFS) but not for relapse-free survival (RFS). When patients with and those without bone marrow involvement were considered separately, anemia remained an adverse factor. Anemia was significantly associated with shorter PFS in small lymphocytic or lymphoplasmacytoid, mantle cell, diffuse large cell and high-grade lymphomas and with shorter OS in all histologic subgroups except marginal zone lymphoma. In multivariate analysis, anemia was a significant prognostic factor for OS and PFS for the population as a whole (P = 0.0001 and P = 0.0048, respectively) and in patients with bone marrow involvement (P = 0.007 and P = 0.005, respectively) but not in patients without bone marrow involvement. Finally, the addition of anemia to the International Prognostic Index led to an improvement for OS (P = 0.0004) and PFS (P = 0.0004).

CONCLUSIONS

Anemia is an important adverse prognostic factor for the outcome of lymphoma patients, particularly in some histologic subgroups and in patients with bone marrow involvement.

Anemia in Children With Cancer Is Associated With Decreased Erythropoietic Activity and Not With Inadequate Erythropoietin Production

A defect in erythropoietin (EPO) production has been advocated as being the main cause of anemia presented at time of diagnosis or during treatment by adults with solid tumors. On the basis of this defect, anemic cancer patients, both adults and children, have been treated with recombinant human EPO (rHuEPO). To further elucidate the pathophysiology of anemia in children with cancer, we measured serum soluble transferrin receptor (sTfR), a quantitative marker of erythropoiesis, and serum EPO at time of diagnosis and during chemotherapy in children suffering from solid tumor or leukemia. We determined serum EPO in 111 children (55 leukemia, 56 solid tumors) at time of diagnosis. In the last 44 patients (23 leukemia and 21 solid tumors), sTfR levels were also measured. Serum EPO together with sTfR levels were also determined in 60 children receiving chemotherapy (29 leukemia, 31 solid tumors). These results were compared with those obtained from appropriate control groups. In all patients, we found a highly significant correlation between the logarithm of EPO (log[EPO]) and the hemoglobin (Hb) level. In all subsets of patients, sTfR levels were inappropriately low for the degree of anemia. Neither leukemic nor solid tumor groups showed a significant inverse relationship between log(sTfR) and the Hb level as would be expected in anemic patients with appropriate marrow response. Thus, in children with cancer, anemia is associated with a decreased total bone marrow erythropoietic activity which, in contrast to what has been reported in anemic cancer adults, is not related to defective EPO production.

© 1998 by The American Society of Hematology.

Anemia in Children With Cancer Is Associated With Decreased Erythropoietic Activity and Not With Inadequate Erythropoietin Production

A defect in erythropoietin (EPO) production has been advocated as being the main cause of anemia presented at time of diagnosis or during treatment by adults with solid tumors. On the basis of this defect, anemic cancer patients, both adults and children, have been treated with recombinant human EPO (rHuEPO). To further elucidate the pathophysiology of anemia in children with cancer, we measured serum soluble transferrin receptor (sTfR), a quantitative marker of erythropoiesis, and serum EPO at time of diagnosis and during chemotherapy in children suffering from solid tumor or leukemia. We determined serum EPO in 111 children (55 leukemia, 56 solid tumors) at time of diagnosis. In the last 44 patients (23 leukemia and 21 solid tumors), sTfR levels were also measured. Serum EPO together with sTfR levels were also determined in 60 children receiving chemotherapy (29 leukemia, 31 solid tumors). These results were compared with those obtained from appropriate control groups. In all patients, we found a highly significant correlation between the logarithm of EPO (log[EPO]) and the hemoglobin (Hb) level. In all subsets of patients, sTfR levels were inappropriately low for the degree of anemia. Neither leukemic nor solid tumor groups showed a significant inverse relationship between log(sTfR) and the Hb level as would be expected in anemic patients with appropriate marrow response. Thus, in children with cancer, anemia is associated with a decreased total bone marrow erythropoietic activity which, in contrast to what has been reported in anemic cancer adults, is not related to defective EPO production.

© 1998 by The American Society of Hematology.

Fas Ligand Is Present in Human Erythroid Colony-Forming Cells and Interacts With Fas Induced by Interferon γ to Produce Erythroid Cell Apoptosis

Interferon γ (IFNγ) inhibits the growth and differentiation of highly purified human erythroid colony-forming cells (ECFCs) and induces erythroblast apoptosis. These effects are dose- and time-dependent. Because the cell surface receptor known as Fas (APO-1; CD95) triggers programmed cell death after activation by its ligand and because incubation of human ECFCs with IFNγ produces apoptosis, we have investigated the expression and function of Fas and Fas ligand (FasL) in highly purified human ECFCs before and after incubation with IFNγ in vitro. Only a small percentage of normal human ECFCs express Fas and this is present at a low level as detected by Northern blotting for the Fas mRNA and flow cytometric analysis of Fas protein using a specific mouse monoclonal antibody. The addition of IFNγ markedly increased the percentage of cells expressing Fas on the surface of the ECFCs as well as the intensity of Fas expression. Fas mRNA was increased by 6 hours, whereas Fas antigen on the cell surface increased by 24 hours, with a plateau at 72 hours. This increase correlated with the inhibitory effect of IFNγ on ECFC proliferation. CH-11 anti-Fas antibody, which mimics the action of the natural FasL, greatly enhanced IFNγ-mediated suppression of cell growth and production of apoptosis, indicating that Fas is functional. Expression of FasL was also demonstrated in normal ECFCs by reverse transcriptase-polymerase chain reaction and flow cytometric analysis with specific monoclonal antibody. FasL was constitutively expressed among erythroid progenitors as they matured from day 5 to day 8 and IFNγ treatment did not change this expression. Apoptosis induced by IFNγ was greatly reduced by the NOK-2 antihuman FasL antibody and an engineered soluble FasL receptor, Fas-Fc, suggesting that Fas-FasL interactions among the ECFCs produce the erythroid inhibitory effects and apoptosis initiated by IFNγ.

High-dose recombinant human erythropoietin stimulates reticulocyte production in patients with multiple organ dysfunction syndrome

OBJECTIVE

To investigate erythropoietin (EPO) production and the erythropoietic potency of recombinant human EPO in the multiple organ dysfunction syndrome.

DESIGN

Randomized, prospective, controlled clinical trial.

MATERIALS AND METHODS

Patients received either 600 IU/kg intravenous EPO three times weekly (n = 9) or saline (control, n = 10).

MEASUREMENTS

EPO levels, circulating soluble receptors for tumor necrosis factor and interleukin-2, levels of interleukin-6 and intercellular adhesion molecule, and early peripheral blood cell progenitors.

RESULTS

EPO production in the control group remained low. Pharmacologic EPO blood levels were associated with increased reticulocyte counts compared with both controls (p < 0.04) and baseline (p < 0.006). Increased levels of soluble receptors for tumor necrosis factor in the treatment group compared with the controls did not prevent this effect. Interleukin 6 inhibited reticulocyte production.

CONCLUSION

Despite increased cytokine levels, pharmacologic EPO blood levels were associated with increased reticulocyte counts in patients with multiple organ dysfunction syndrome.

Iron, anemia, and infection

The data on the relationship between iron deficiency and infection are conflicting. Some researchers conclude that mild iron deficiency is beneficial for immunity, whereas others contend that any deficit is not good for immunity. Additionally, infection or inflammation generate anemia and profound changes in iron metabolism mediated by cytokines. These changes are important confounders to consider in assessments of iron status.

Interferon-alpha inhibits CFU-GM mobilization following chemotherapy and G-CSF administration

Changes in routine hematologic data and in circulating granulocyte-macrophage colony-forming units (CFU-GM) during granulocyte colony-stimulating factor (G-CSF) administration were evaluated in non-small cell lung carcinoma (NSCLC) patients treated with a combination of 5-fluorouracil (5-FU) and cisplatin (DDP) with and without the addition of interferon-alpha (IFN-alpha). The patterns of leukocyte changes following chemotherapy plus G-CSF were similar in both the IFN-alpha-inclusive and the IFN-alpha-devoid courses. However, the twofold increase in CFU-GM observed in patients receiving chemotherapy plus G-CSF was completely absent following the course including IFN-alpha. The activity of G-CSF on the hematologic pattern is seemingly affected by its combination with IFN-alpha treatment. Mechanisms of the possible in vivo interaction among IFNs and hematopoietic growth factors remain to be elucidated.

The comparison of 2-chlorodeoxyadenosine (2-Cd A) in combination with interferon alpha (IFN alpha) or interferon gamma (IFN gamma) on granulocyte-macrophage progenitor cells (CFU-GM) and clonogenic blasts in (CFU-L) in vitro cultures

In the present in vitro study we investigated the influence of 2-chlorodeoxyadenosine (2-CdA) and interferon gamma (IFNgamma) on the clonal growth of granulocyte macrophage progenitor (CFU-GM) cells from 10 normal individuals and from 10 patients with chronic myeloid leukemia (CML) and on CFU-L blasts from 10 patients with acute myeloid leukemia (AML). 2-CdA was added to the culture medium at 20nM/l, 40nM/l and 80nM/l concentrations and IFNgamma at concentrations of 10(2)U/ml, 10(3)U/ml and 10(4)U/ml. Both agents were used alone and in combination with these different concentrations. We observed a decrease in the number of colonies formed by CML CFU-GM as well as by AML CFU-L in a dose-dependent manner. The drugs used alone inhibited to a higher degree the growth of CML than of normal CFU-GM progenitors. 2-CdA and IFN gamma showed the greatest additive effect on the growth of CFU-L blasts at the concentrations of 80nM/l and 10(4)U/ml, respectively. We compared our results with previous in vitro studies in which we have demonstrated the synergistic inhibitory effect of 2-CdA and IFN alpha on both normal and leukemic hematopoiesis. We suggest that the greatest inhibitory effect is observed when 2-CdA and IFN alpha at the highest concentration are added together to the culture of AML CFU-L blasts.

Evidence suggesting a stimulatory role for interleukin-10 in erythropoiesis in vitro

Interleukin-10 (IL-10) has been shown to exert anti-inflammatory effects by suppressing macrophage proliferation and inhibiting cytokine production. In this study we show that in the presence of erythropoietin (EPO), the addition of IL-10 results in a significant dose-dependent increase in both Burst Forming Unit-Erythroid (BFU-E) and Colony Forming Unit-Erythroid (CFU-E) colony growth in both serum-containing and serum-free murine cultures in vitro. IL-10 acts at the later stages of erythroid cell proliferation and differentiation as the increase in colony number was greater in CFU-E than in BFU-E, and was similar when IL-10 was added to BFU-E cultures at the time of culture initiation as when its addition to culture was delayed for 7 days. Furthermore, no increase in BFU-E colony number was noted when IL-10, added at the time of culture initiation, was neutralized by the addition to culture of a monoclonal anti-IL-10 antibody up to 7 days later. The increases in BFU-E by IL-10 addition were not the result of prolongation of BFU-E colony lifespan, which was not significantly different in IL-10 treated and control cultures, respectively. Rather IL-10 stimulated the proliferation of erythroid clusters that were now large enough to be recognized as colonies. IL-10-induced stimulation of erythropoiesis appeared to be independent of its inhibitory effects on macrophage function, as stimulation of erythroid colony growth was similar in macrophage-containing and depleted cultures. Studies to determine if the IL-10 effect was direct or indirect yielded equivocal results. A limiting dilution assay suggested a direct effect. However, a log/log dose response curve with IL-10 did not pass through the origin suggesting an indirect effect. These studies indicate that IL-10 acts synergistically with EPO to significantly increase stimulation of erythroid differentiation and proliferation in vitro and may be involved in the regulation of normal erythropoiesis in vivo.

Stem cell factor can overcome inhibition of highly purified human burst-forming units-erythroid by interferon gamma

Highly purified human blood burst-forming units-erythroid (BFU-E) were used to study the effects of interferon gamma (IFN gamma). IFN gamma inhibited erythroid colony formation, cell proliferation, and differentiation of day 3 to day 6 mature BFU-E in a dose-dependent manner. The primitive BFU-E (day 1 and day 2 cells) and later day 7 cells were less affected. IFN gamma dose-response experiments demonstrated that the number and size of erythroid colonies were reduced at a concentration of 500 U/ml with more complete inhibition at 1,000 U/ml. Inhibition of day 4 to day 6 erythroid progenitors was first noted by 72 h of incubation with IFN gamma, and target cell growth and differentiation continued to decrease with further incubation. IFN gamma also induced erythroblast apoptosis which was demonstrated by both nuclear condensation and fragmentation plus flow cytometry with in situ end-labelling. Because day 3 to day 6 cells need stem cell factor (SCF) for development in serum-free culture, the relationship of IFN gamma inhibition to this growth factor was investigated. The reduction in the number of erythroid colonies by IFN gamma was reversed by SCF although the colony size was not completely re-established. In contrast, interleukin-3 did not have the capacity to overcome the inhibitory effects of IFN gamma. Since IFN gamma blood levels are elevated in some anemias of chronic disease, IFN gamma may have a role in promoting this anemia and its inhibitory effect might be better overcome by SCF plus EP. However, the mechanism by which these growth factors overcome the inhibition of IFN gamma, or vice versa, is unknown at the present time.

Effect of age on marrow macrophage number and function

Employing flow cytometry and a monoclonal antibody against the murine macrophage antigen, Mac-1, we found a significant increase in the number of marrow macrophages in aged mice. This was reflected as significant increase with age in the number of alpha-naphthyl acetate esterase positive cells, as well as in colony forming unit-macrophage (CFU-M) progenitor cells. Macrophages from the marrow of old mice generated significantly less tumor necrosis factor alpha (TNF alpha) than did macrophages from young mice, either spontaneously or when activated by granulocyte-macrophage colony stimulating factor (GM-CSF). Furthermore, conditioned medium (CM) derived from either marrow or peritoneal macrophages of old mice caused less suppression of burst forming unit-erythroid (BFU-E) colony growth than did CM obtained from young mice. Aging, therefore, is associated with an increase in the number of marrow macrophages that have an impaired ability to generate or release cytokines. The increase in macrophage number may reflect a compensation for their reduced function. Altered macrophage number and function may contribute to the age-related decline in hematopoietic reserve capacity.

Erythropoiesis and erythropoietin in multiple myeloma

In this review, the pathophysiology and treatment of the anemia of multiple myeloma will be examined. While the anemia of cancer has multiple causes, an important component is labeled the "anemia of chronic disease" which is characterized by the combination of a shortened erythrocyte survival with failure of the bone marrow to increase red cell production in compensation. Depressed erythropoiesis is itself related to a combination of factors, including impaired availability of storage iron, inadequate erythropoietin response to anemia, and overproduction of cytokines which are capable of inhibiting erythropoiesis. These cytokines are involved in the retention of iron in the reticuloendothelial system, gastrointestinal tract and hepatocytes, may interfere with erythropoietin production by the kidney, and may exert direct inhibitory effects on erythroid precursors. While overproduction of several such cytokines, including IL-6, IL-1 and TNF-alpha, has been definitely demonstrated in multiple myeloma patients, it is still unclear whether they are directly involved in the pathogenesis of the anemia which develops. Although several mechanisms, such as hemodilution, bleeding, and decreased red cell survival operate, the anemia is mostly caused by defective erythropoietic activity. This in turn is partly explained by inadequate erythropoietin (Epo) production even in some patients without renal impairment. Based on measurements of serum erythropoietin and transferrin receptor, the distinction between marrow unresponsiveness to normal Epo stimulation and deficient Epo production is important for the treatment of the anemia of multiple myeloma with recombinant human Epo. Higher doses would probably be necessary if adequate Epo production is present, whereas only replacement therapy with lower doses may be sufficient when Epo production has been shown to be inappropriate.

Pathogenesis of the anemia of chronic disease: a cytokine-mediated anemia

The anemia found in patients with chronic infectious, inflammatory and neoplastic disorders, known as the anemia of chronic disease (ACD), is one of the most common syndromes in medicine. A characteristic finding of the disorders associated with ACD is increased production of the cytokines which mediate the immune or inflammatory response, such as tumor necrosis factor, interleukin 1 and the interferons. All the processes involved in the development of ACD can be attributed to these cytokines, including shortened red cell survival, blunted erythropoietin response to anemia, impaired erythroid colony formation in response to erythropoietin and abnormal mobilization of reticuloendothelial iron stores. Improved understanding of the role played by cytokines in the pathogenesis of ACD may lead to the development of more specific therapy for this syndrome.

Interferon-gamma exerts its negative regulatory effect primarily on the earliest stages of murine erythroid progenitor cell development

Interferon-gamma (INF-gamma) has been shown to suppress erythropoiesis and perhaps to contribute to the anemia of chronic disease. In this study we demonstrated that the concentration of INF gamma required to suppress murine burst forming unit-erythroid (BFU-E) growth was significantly less than that required to suppress colony forming unit-erythroid (CFU-E) growth. INF gamma acted at the most primitive step in erythroid progenitor cell differentiation and proliferation, as inhibition was maximal when added at the time of BFU-E culture initiation. Inhibition was progressively less if INF gamma addition was delayed after culture initiation. The effects of INF gamma on BFU-E did not require the presence of interleukin-1 alpha (IL-1 alpha), tumor necrosis factor-alpha (TNF alpha), or granulocyte macrophage colony stimulating factor (GM-CSF), as its effects were not neutralized by monoclonal antibodies against IL-1 alpha, TNF alpha, or GM-CSF. This applied whether INF gamma was added to culture with individual antibodies or with a combination of all three antibodies. INF gamma was not required for IL-1 alpha- or TNF alpha-induced suppression of BFU-E, as their effects were not neutralized by a monoclonal anti-INF gamma antibody. In contrast, GM-CSF-induced suppression of BFU-E was negated by the simultaneous addition of anti-INF gamma. We have previously shown that the addition of TNF alpha does not suppress BFU-E growth in cultures from marrow depleted of macrophages. Suppression did occur, however, if a small concentration of INF gamma that does not inhibit and increasing concentration of TNF alpha were added to culture, suggesting a synergistic effect between INF-gamma and TNF alpha. These observations suggest that INF gamma is a potent direct inhibitor of erythroid colony growth in vitro. It exerts its negative regulatory effect primarily on the earliest stages of erythroid progenitor cell differentiation and proliferation, as much higher doses are required to suppress late erythroid cell development. INF gamma is also involved in GM-CSF-induced inhibition of BFU-E colony growth.

Hematopoietic progenitors and synergism of interferon-gamma and stem cell factor

Interferon-gamma (IFN-gamma), an immunoregulatory cytokine produced by activated T cells and natural killer cells in response to viral infection or other stimuli, is generally recognized as a suppressor of hematopoiesis. IFN-gamma inhibited in vitro colony formation by granulocyte-macrophage (GM), erythroid and multipotential progenitors. This cytokine exerted direct suppression on the proliferation process, but not on the commitment, of GM progenitors. The antiproliferative effects of IFN-gamma may, in part, result from the prolongation of the doubling time of GM progenitors. Clinically, IFN-gamma may play an important role in the pathogenesis of pancytopenia in aplastic anemia and in the hemophagocytic syndrome. However, as well as showing inhibitory effects, IFN-gamma increased the number of pure and mixed megakaryocyte colonies formed by post-5-fluorouracil treated bone marrow cells and, moreover, the addition of IFN-gamma to culture containing stem cell factor resulted in a synergistic effect on the development of both primitive hematopoietic progenitors and mature populations. These findings suggest that IFN-gamma has bifunctional activity in hematopoiesis.