Suppression Of Erythropoiesis Research Articles

Effects of erythropoietin on erythrocyte deformability in non‐transfused preterm infants

Suppression of erythropoiesis due to low plasma erythropoietin levels is an important factor in the development of anaemia of prematurity. Premature infants may therefore be treated with recombinant human erythropoietin (rhEPO). This prospective, randomised and controlled study was designed to find out whether rhEPO treatment improves erythrocyte deformability in preterm infants. Sixteen infants were treated with rhEPO (250 IU/kg three times weekly) a total of 15 times beginning on day of life 5 whereas fifteen infants served as controls. Haemoglobin concentration, haematocrit, reticulocyte count, ferritin level and erythrocyte deformability were measured on days 5, 14, 28, 42 and 63. Erythrocyte elongation was determined as an indicator of erythrocyte deformability using a shear stress diffractometer (Rheodyn SSD) at shear forces of 0.3 to 60 Pa. Haemoglobin concentration was significantly higher on days 28 and 42 and reticulocyte percentage on day 28 in the rhEPO group compared to the controls. Serum ferritin was lower in the rhEPO group on day 28. Erythrocyte deformability was significantly increased on days 28 and 42 in the infants receiving rhEPO. We found a strong relationship between erythrocyte elongation and reticulocyte count. RhEPO markedly increases the erythropoiesis in preterm infants in the critical first weeks of life and the anaemia of prematurity is obviously reduced. The erythrocyte deformability improved under rhEPO treatment. Erythrocyte deformability was significantly related to the reticulocyte count indicating that the improvement of erythrocyte deformability was due to the formation of well-deformable young erythrocytes.

USE OF RECOMBINANT ERYTHROPOIETIN FOR THE MANAGEMENT OF SEVERE HEMOLYTIC DISEASE OF THE NEWBORN OF A K0 PHENOTYPE MOTHER

Very few people do not express any Kell antigens on their red blood cells (K0 phenotype). They can be immunized by transfusion or pregnancy and develop antibodies against Kell system antigens. These maternal antibodies can cause severe hemolytic disease of the fetus/newborn, as a result of the suppression of erythropoiesis and hemolysis. Multiple intrauterine transfusions in the management of severe hemolytic disease have been shown to cause erythropoietic suppression as well. Recombinant erythropoietin has been successfully used in the management of late anemia of infants with Rh hemolytic disease and in 1 case of KEL1 (Kell)-associated hemolytic disease. The authors present the case of severe hemolytic disease of a newborn due to KEL5 (Ku) isoimmunization of his K0 phenotype mother. Regular intrauterine transfusions were performed to manage the severe fetal anemia (Hb 3 g/dL). A male infant was born at the 36th week of gestation having normal hemoglobin (15.8 g/dL) and developed only mild hyperbilirubinemia. On the 15th day of life, the infant's hematocrit had fallen to 27.3%, with low reticulocyte count and low erythropoietin level. The infant was managed successfully with recombinant erythropoietin.

A small-scale serum-free liquid cell culture model of erythropoiesis to assess the effects of exogenous factors

Anaemia is an important global health problem. Therefore, it is crucial to understand its pathophysiology in various genetic or infectious diseases where dyserythropoiesis is a key pathological feature. To this effect, reproducible and reliable models of erythropoiesis in vitro are much needed as investigative tools. We have developed a serum-free liquid culture model of erythropoiesis using human umbilical cord blood CD34 + cells cultured in the cytokine combination, interleukin-3 (IL-3), IL-6, stem cell factor (SCF) and erythropoietin (Epo), over 14 days. We found that these culture conditions favored erythroid differentiation over the expansion of the more primitive erythroid precursors. With an initiating culture density of 5 × 10 4 cells per ml, the nucleated cell fold expansion increased from 7.9 ± 3.9 (range 4.5 to 11.1) after 4 days to 2990.2 ± 1936.1 (range 626.6 to 6912.0) after 14 days in culture. Day-14 burst-forming unit-erythroid (BFU-E) frequencies peaked at day 4 (24.0 ± 8.9%), with a marked decrease in BFU-E burst size as the cultures progressed. Time-course immunophenotypical profiles were characteristically erythroid with a decrease in CD34 expression (from 96.8 ± 3.0% at day 0 to 0.8 ± 0.8% at day 14), and a concomitant increase in the expression of erythroid-specific markers, CD36, glycophorin A (GpA) and CD71 (from 14.8 ± 5.0%, 1.7 ± 1.0% and 37.9 ± 18.0% to 93.0 ± 7.0%, 82.1 ± 14.0% and 95.7 ± 3.0%, respectively). Morphological studies revealed the presence of normoblasts with the complete absence of reticulocytes and mature erythrocytes after 14 days in culture. Once the culture conditions were optimized, we scaled down our culture model from 24-well plate (large-scale) to 96-well plate cultures (small-scale). We found that the small-scale cultures compared favorably with their large-scale counterpart in terms of erythroid progenitor cell proliferation and differentiation, particularly at low CD34 + initiating cell doses. By using tumor necrosis factor-alpha (TNF-α), a known inhibitor of erythropoiesis, we validated our model system and showed a dose-dependent inhibition of erythroid differentiation with TNF-α in our cultures. Therefore, our results demonstrate a small-scale serum-free liquid culture model of erythropoiesis that is comparable with and complements our well-defined large-scale model. Our system would prove useful for screening the effects of exogenous factors on erythropoiesis in vitro.

Suppression of hepcidin during anemia requires erythropoietic activity

AbstractHepcidin, the principal iron regulatory hormone, regulates the absorption of iron from the diet and the mobilization of iron from stores. Previous studies indicated that hepcidin is suppressed during anemia, a response that would appropriately increase the absorption of iron and its release from stores. Indeed, in the mouse model, hepcidin-1 was suppressed after phlebotomy or erythropoietin administration but the suppression was reversed by inhibitors of erythropoiesis. The suppression of hepcidin necessary to match iron supply to erythropoietic demand thus requires increased erythropoiesis and is not directly mediated by anemia, tissue hypoxia, or erythropoietin.

Role of Monocyte-Acquired Hemozoin in Suppression of Macrophage Migration Inhibitory Factor in Children with Severe Malarial Anemia

Severe malarial anemia (SMA), caused by Plasmodium falciparum infections, is one of the leading causes of childhood mortality in sub-Saharan Africa. Although the molecular determinants of SMA are largely undefined, dysregulation in host-derived inflammatory mediators influences disease severity. Macrophage migration inhibitory factor (MIF) is an important regulator of innate inflammatory responses that has recently been shown to suppress erythropoiesis and promote pathogenesis of SMA in murine models. To examine the role of MIF in the development of childhood SMA, peripheral blood MIF production was examined in Kenyan children (aged <3 years, n = 357) with P. falciparum malarial anemia. All children in the study were free from bacteremia and human immunodeficiency virus type 1. Since deposition of malarial pigment (hemozoin [Hz]) contributes to suppression of erythropoiesis, the relationship between MIF concentrations and monocytic acquisition of Hz was also examined in vivo and in vitro. Circulating MIF concentrations declined with increasing severity of anemia and significantly correlated with peripheral blood leukocyte MIF transcripts. However, MIF concentrations in peripheral blood were not significantly associated with reticulocyte production. Multivariate regression analyses, controlling for age, gender, and parasitemia, further revealed that elevated levels of pigment-containing monocytes (PCM) was associated with SMA and decreased MIF production. In addition, PCM levels were a better predictor of hemoglobin and MIF concentrations than parasite density. Additional experiments in malaria-naive individuals demonstrated that hemozoin caused both increased and decreased MIF production in cultured peripheral blood mononuclear cells (PBMC) in a donor-specific manner, independent of apoptosis. However, PBMC MIF production in children with acute malaria progressively declined with increasing anemia severity. Results presented here demonstrate that acquisition of hemozoin by monocytes is associated with suppression of peripheral blood MIF production and enhanced severity of anemia in childhood malaria.

Suppression of erythropoiesis in malarial anemia is associated with hemozoin in vitro and in vivo

AbstractMalarial anemia is a global public health problem and is characterized by a low reticulocyte response in the presence of life-threatening hemolysis. Although cytokines, in particular tumor necrosis factor-α (TNF-α), can suppress erythropoiesis, the grossly abnormal bone marrow morphology indicates that other factors may contribute to ineffective erythropoiesis. We hypothesized that the cytotoxic hemozoin (Hz) residues from digested hemoglobin (Hb) significantly contribute to abnormal erythropoiesis. Here, we show that not only isolated Hz, but also delipidated Hz, inhibits erythroid development in vitro in the absence of TNF-α. However, when added to cultures, TNF-α synergizes with Hz to inhibit erythropoiesis. Furthermore, we show that, in children with malarial anemia, the proportion of circulating monocytes containing Hz is associated with anemia (P < .001) and reticulocyte suppression (P = .009), and that this is independent of the level of circulating cytokines, including TNF-α. Plasma Hz is also associated with anemia (P < .001) and reticulocyte suppression (P = .02). Finally, histologic examination of the bone marrow of children who have died from malaria shows that pigmented erythroid and myeloid precursors are associated with the degree of abnormal erythroid development. Taken together, these observations provide compelling evidence for inhibition of erythropoiesis by Hz.

Interferon-γ mediates suppression of erythropoiesis but not reduced red cell survival following CpG-ODN administration in vivo

Cytokines released during inflammatory processes have been proposed to play a central role in mediating mechanism(s) leading to anemia. Here, we used CpG-ODN to investigate the effects of a pro-inflammatory response on the pathophysiological processes leading to anemia. Naïve and erythropoietin (EPO)-treated mice were injected for 2 days with 100 microg CpG-ODN or control ODN and the effects on the course of red blood cell (RBC) and reticulocyte counts, RBC turnover, and EPO-stimulated maturation of erythroid cells were analyzed. To study the effect of CpG-ODN on erythroid cell maturation in vitro, we obtained primary EPO-responsive cells by treating mice with thiamphenicol (15 mg/g body weight). CpG-ODN-treated mice developed anemia, which persisted for 5 days and was associated with a 50% reduction in EPO-stimulated differentiation of EPOR+ cells to TER119+ erythroblasts. CpG-ODN-induced suppression required accessory cells, including antigen presenting cells, which activated other cells to produce pro-inflammatory cytokines. In vitro neutralization of IFN-gamma, but not IL-12, TNF-alpha, IFN-alpha, IL-1alpha, or IL-1beta, abrogated the erythropoietic suppression induced by CpG-ODN. The anemia observed in CpG-ODN-treated mice was also associated with reduced RBC survival in vivo, as demonstrated by a sevenfold to eightfold higher turnover of biotinylated RBC compared to control ODN-treated mice. In vivo IFN-gamma neutralization confirmed that IFN-gamma contributed to erythropoietic suppression but not reduced RBC survival. Together, these results demonstrate that CpG-ODN anemia is associated with suppressed erythropoiesis and decreased RBC survival. Importantly, CpG-ODN-induced IFN-gamma was found to be the major factor mediating erythropoietic suppression but not decreased RBC survival.

Recombinant human erythropoietin therapy after allogeneic hematopoietic cell transplantation with a nonmyeloablative conditioning regimen: Low donor chimerism predicts for poor response

After allogeneic hematopoietic stem cell transplantation with nonmyeloablative conditioning (NMHCT), many patients experience prolonged anemia and require red blood cell (RBC) transfusions. We enrolled 60 consecutive patients undergoing NMHCT in a phase II trial to determine the optimal utilization of recombinant human erythropoietin (rHuEPO) therapy in this setting. The first 14 NMHCT recipients did not receive rHuEPO (control group). Nineteen patients were scheduled to start rHuEPO on day 0 (EPO group 2) and 27 patients on day 28 after the transplant (EPO group 1). RHuEPO was administered subcutaneously once weekly at a dose of 500 U/kg/wk with the aim of achieving hemoglobin (Hb) levels of 13 g/dL. The 3 groups were well balanced for major characteristics. During the first month (p < 0.0001) as well as days 30 to 100 (p < 0.0001) and days 100 to 180 (p < 0.0001), Hb values were higher in patients receiving rHuEPO compared to those not receiving it. However, transfusion requirements were significantly decreased only in the first month in EPO group 2 (p = 0.0169). T-cell chimerism above 60% on day 42 was the best predictor of Hb response (p < 0.0001) or Hb correction (p = 0.0217), but myeloid chimerism above 90% also predicted for Hb response (p = 0.0069). Hb response was also decreased in patients receiving CD8-depleted grafts and increased in the few patients not receiving TBI, but only in univariate analysis. Anemia after NMHCT is sensitive to rHuEPO therapy, but less so than after conventional allogeneic HCT. RHuEPO decreases transfusion requirements only in the first 30 days posttransplant. T-cell chimerism below 60% on day 42 impaired Hb response, suggesting possible inhibition of donor erythropoiesis by residual recipient lymphocytes. A prospective randomized trial should be performed with rHuEPO starting on the day of transplantation to assess its clinical benefit in terms of transfusion requirements and quality of life.

Weekly (QW) epoetin alfa (EPO) in prostate cancer (PC) patients (pts) with anemia not receiving chemotherapy (CT) or radiation therapy (RT)

14634 Background: While EPO is widely used in the management of CT-related anemia, anemia in cancer pts may stem from causes other than CT. Tumor invasion of the bone marrow and cytokine-mediated inhibition of erythropoiesis are among the many disease-related causes of anemia in cancer. Data evaluating the use of EPO in pts not receiving CT or RT, particularly in specific tumor types, would be important information to healthcare providers. Methods: An open-label, prospective, non-randomized, multicenter pilot study was conducted to evaluate the efficacy and safety of EPO 40,000 U QW in anemic (hemoglobin [Hb] ≤ 11 g/dL) cancer pts not receiving CT or RT1. (Blood 2004;104:abstract 4223.) Treatment duration was up to 12 wks with a 4-wk post-treatment observation period. Primary efficacy endpoint was hematopoietic response during the treatment period (% of pts achieving a ≥ 1 or ≥ 2 g/dL Hb increase from baseline [BL]). Secondary endpoints included change from BL in quality of life as measured by the Linear Analog Scale Assessment (LASA). This is a retrospective subset analysis of PC pts (n = 24) enrolled in the prospective study. Results: For the safety population (all pts who received ≥ 1 EPO dose, n = 23), mean age was 71.4 ± 6.8 yrs; 21 (91.3%) had ECOG status of 0 or 1; and mean BL Hb was 10.4 ± 0.8 g/dL. Of 21 pts evaluated for efficacy, 17 (81.0%) achieved Hb increase from BL ≥ 2 g/dL, while 19 (90.5%) achieved ≥ 1 g/dL by wk 17/early withdrawal. EPO dose was increased in 5 (23.8%) pts (to 60,000 U for Hb increase &lt; 1 g/dL after 4 wks) and held in 16 (76.2%) pts (due to Hb &gt; 13 g/dL, with dosing resumed when Hb was ≤12 g/dL, at 30,000 U from 40,000 U or at 40,000 U from 60,000 U). Both Wk 9 and 17 LASA scores increased significantly from BL in all categories (Energy Level, Daily Activities, and Quality of Life; P &lt; 0.001). 15 of 23 pts (65.2%) had at least one adverse event (AE); 4 (17.4%) pts had at least one serious AE. No clinically relevant thrombotic vascular events were noted. No pt received transfusion. 5 pts discontinued: 2 for AEs, 1 at pt request, and 2 at study sponsor request. Conclusions: This retrospective analysis suggests that EPO 40,000 U QW is safe and effective for treating anemia in PC pts not receiving CT or RT. [Table: see text]

Can Granulocyte-Colony Stimulating Factor Worsen Anemia?

Can Granulocyte-Colony Stimulating Factor Worsen Anemia?

Lanthanum carbonate versus standard therapy for the treatment of hyperphosphatemia: safety and efficacy in chronic maintenance hemodialysis patients

No conventional phosphate binder is entirely satisfactory for the treatment of hyperphosphatemia in patients with end-stage renal disease (ESRD). Consequently, there is a need for new agents. One such agent is lanthanum carbonate (La). This large-scale study compares the safety of La with standard therapy (any approved phosphate binder) in patients who were treated for up to 2 years. Efficacy, having previously been demonstrated, was a secondary endpoint. After washout, patients were randomized to receive La (n=682) or their pre-study phosphate binder (n=677). Over a 6-week period, La was titrated to a maximum daily dose of 3000 mg elemental lanthanum (serum phosphorus target levels for titration were < or = 5.9 mg/dl (1.90 mmol/l)). Safety assessments included adverse events (AEs), full laboratory parameters and blood profiles. Efficacy assessments included serum phosphorus, calcium, calcium x phosphorus product and parathyroid hormone (PTH) levels. Average treatment exposure was greater in the standard therapy group (501.4 days) than in the La group (370.3 days) because standard therapy patients who switched or combined treatments were allowed to continue in the study. The most common AEs were gastrointestinal. The incidences of AEs in the La and treatment exposure-corrected standard therapy groups were nausea, 37 versus 29%; vomiting, 27 versus 22% and diarrhea (24% in each group). Hypercalcemia that was reported as an AE (La versus treatment exposure-corrected standard therapy) occurred in 4.3% and 8.4% of patients, respectively. There was no indication of liver toxicity, suppression of erythropoiesis or changes in the mini-mental state examination. Over 2 years, phosphorus control was similar in both groups; in the La group, however, serum calcium was lower and serum PTH levels were maintained in the range recommended by the National Kidney Foundation Kidney Disease Outcomes Quality Initiative (K/DOQI). The 2-year tolerability and efficacy of La are similar to those seen with standard therapy, although lower serum calcium levels and improved PTH levels were observed in the La group. These results support La as a viable new option for the management of hyperphosphatemia in ESRD.

Hepcidin mRNA levels in mouse liver respond to inhibition of erythropoiesis

Hepcidin, a key regulator of iron metabolism, decreases intestinal absorption of iron and its release from macrophages. Iron, anemia, hypoxia, and inflammation were reported to influence hepcidin expression. To investigate regulation of the expression of hepcidin and other iron-related genes, we manipulated erythropoietic activity in mice. Erythropoiesis was inhibited by irradiation or posttransfusion polycythemia and stimulated by phenylhydrazine administration and erythropoietin. Gene expression of hepcidin and other iron-related genes (hemojuvelin, DMT1, ferroportin, transferrin receptors, ferritin) in the liver was measured by the real-time polymerase chain reaction. Hepcidin expression increased despite severe anemia when hematopoiesis was inhibited by irradiation. Suppression of erythropoiesis by posttransfusion polycythemia or irradiation also increased hepcidin mRNA levels. Compensated hemolysis induced by repeated phenylhydrazine administration did not change hepcidin expression. The decrease caused by exogenous erythropoeitin was blocked by postirradiation bone marrow suppression. The hemolysis and anemia decrease hepcidin expression only when erythropoiesis is functional; on the other hand, if erythropoiesis is blocked, even severe anemia does not lead to a decrease of hepcidin expression, which is indeed increased. We propose that hepcidin is exclusively sensitive to iron utilization for erythropoiesis and hepatocyte iron balance, and these changes are not sensed by other genes involved in the control of iron metabolism in the liver.

Hyporesponsiveness to erythropoietic therapy due to chronic inflammation

The anaemia associated with chronic renal failure is multi-factorial. Although a relative erythropoietin deficiency is a major factor, it has also been recognized in recent times that uraemia is a chronic inflammatory state, and thus patients with renal failure also develop anaemia due to mechanisms associated with chronic inflammation. Thus, patients with chronic renal failure have activation of various immune cells, both monocytes and T-cells. These mononuclear cells have also been shown to release pro-inflammatory cytokines such as IL-1, IL-6, TNF-alfa and interferon gamma. These cytokines, particularly TNF-alfa and interferon gamma, are known to cause significant suppression of erythropoiesis. The exact molecular mechanism for this effect is not yet clear, but interferon gamma is an important stimulator of apoptosis in various cell types, including erythroid progenitor cells. This effect may be potentiated by other cytokines such as TNF-alfa, and this might then antagonise the anti-apoptotic action of erythropoietin on erythroid progenitors cells, thus reducing responsiveness to exogenous erythropoietic therapy. Chronic renal failure is also associated with increased hepcidin production which may also exacerbate the anaemia by inducing a functional iron deficiency in such patients.

Protection against malaria by anti‐erythropoietin antibody due to suppression of erythropoiesis in the liver and at other sites

We have previously reported that erythropoiesis commences in the liver and spleen after malarial infection, and that newly generated erythrocytes in the liver are essential for infection of malarial parasites as well as continuation of infection. At this time, erythropoietin (EPO) is elevated in the serum. In the present study, we administered EPO or anti-EPO antibody into C57BL/6 (B6) mice to modulate the serum level of EPO. When mice were infected with a non-lethal strain (17NXL) of Plasmodium yoelii (blood-stage infection of 10(4) parasitized erythrocytes per mouse), parasitemia continued for 1 month, showing a peak at day 17. Daily injection of EPO (200 IU/day per mouse) from day five to day 14 prolonged parasitemia, whereas injection of anti-EPO antibody (1.5 mg/day per mouse) every second day from day five to day 28 decreased it. Erythropoiesis was confirmed in the liver, spleen and bone marrow by the appearance of nucleated erythrocytes (TER119+). When anti-EPO antibody was injected by the same protocol into mice infected with a lethal strain (17XL) of P. yoelii, all mice showed decreased parasitemia and recovered from the infection. These results suggest that the use of anti-EPO antibody after malarial infection may be of therapeutic value in severe cases of malaria.

Multiple Members of the TNF Superfamily Contribute to IFN-γ-Mediated Inhibition of Erythropoiesis

IFN-gamma inhibits the growth and differentiation of erythroid precursor cells and mediates hemopoietic suppression through mechanisms that are not completely understood. We found that treatment of human erythroid precursor cells with IFN-gamma up-regulates the expression of multiple members of the TNF family, including TRAIL and the recently characterized protein TWEAK. TWEAK and its receptor fibroblast growth factor-inducible 14 (Fn14) were expressed by purified erythroblasts at all the stages of maturation. Exposure to recombinant TWEAK or agonist anti-Fn14 Abs was able to inhibit erythroid cell growth and differentiation through caspase activation. Because other members of the TNF family such as TRAIL and CD95 ligand (CD95L) are known to interfere with erythroblast growth and differentiation, we investigated the role of different TNF/TNFR family proteins as potential effectors of IFN-gamma in the immature hemopoietic compartment. Treatment of erythroid precursor cells with agents that blocked either TRAIL, CD95L, or TWEAK activity was partially able to revert the effect of IFN-gamma on erythroid proliferation and differentiation. However, the simultaneous inhibition of TRAIL, TWEAK, and CD95L resulted in a complete abrogation of IFN-gamma inhibitory effects, indicating the requirement of different receptor-mediated signals in IFN-gamma-mediated hemopoietic suppression. These results establish a new role for TWEAK and its receptor in normal and IFN-gamma-mediated regulation of hematopoiesis and show that the effects of IFN-gamma on immature erythroid cells depend on multiple interactions between TNF family members and their receptors.

Mechanisms of Regulation of Erythropoiesis during Experimental Neuroses

We studied the mechanisms of erythropoiesis regulation in a conflict situation and during paradoxical sleep deprivation. Plastic reconstruction of the erythroid hemopoietic stem during experimental neuroses is regulated by a complex multicomponent and multilevel system. This system consists of central adrenergic structures, sympathetic part of the autonomic nervous system, and alpha- and beta-adrenoceptors on erythroid precursors and cells of the hemopoietic microenvironment. Erythroid cells receive instructive information from the central nervous system via adrenoceptors on cells of the hemopoiesis-inducing microenvironment and erythroid precursors. Hyperplasia (conflict situation) and suppression of erythropoiesis (paradoxical sleep deprivation) are associated with specificity of central adrenergic regulatory mechanisms.

A novel mechanism in suppression of erythropoiesis during inflammation: a crucial role of RCAS1

A novel human tumor-associated antigen, receptor-binding cancer antigen expressed on SiSo cells (RCAS1), induces apoptosis in normal human erythroid progenitor cells, which express putative RCAS1 receptors. In the present study, we investigated a possible role of RCAS1 produced by human peripheral blood monocytes (CD14-positive cells) and monocyte-derived macrophages. RCAS1 was immunohistochemically detected in monocytes as well as macrophages. When macrophages were stimulated with lipopolysaccharide (LPS), the expression of RCAS1 was remarkably enhanced. An increased production of RCAS1 mRNA was observed in LPS-stimulated macrophages by quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) analysis. Soluble RCAS1 molecules were only detected in the culture supernatants obtained from LPS-stimulated macrophages. Moreover, LPS-stimulated macrophages induced cell death of erythroid progenitor cells through RCAS1 production. These results suggest that macrophages may negatively regulate erythropoiesis at least in part through the production of RCAS1 molecules, and this may contribute to the pathogenesis of the anemia seen in patients with inflammatory disorders.

Late onset neonatal anaemia due to maternal anti‐Ge: possible association with destruction of eythroid progenitors

There have been no reports of severe haemolytic disease of the newborn (HDN) due to Gerbich (Ge) antibodies. Two babies with HDN due to anti-Ge3, both born to the same mother, are described. The anti-Ge appeared in the first pregnancy and was not detectable in the first trimester, the babies' reticulocyte and bilirubin values were not greatly elevated (similar to HDN due to Kell antibodies), and the anaemia in both cases was either not apparent or not severe until 2 to 4 weeks after birth. Ge antigens are found on glycophorins (GPs) C and D; GPC, like Kell, has been shown to be expressed early on erythroid progenitor cells. The maternal anti-Ge3 was shown to promote phagocytosis of Ge+ early erythroid progenitors by monocytes (similar to what has been reported with anti-K and K+ progenitor cells). Thus, anti-Ge3 may cause immune destruction of erythroid progenitors and possibly suppression of erythropoiesis (which would explain the reticulocyte and bilirubin values seen in both cases). Anti-Ge3 appears to be capable of causing severe HDN. We suggest that babies born to mothers with anti-Ge should have their haemoglobin concentrations monitored for signs of anaemia for several weeks after birth. Functional assays may prove useful.

Inflammatory cytokine inhibition of erythropoiesis in patients implanted with a mechanical circulatory assist device

Mechanical circulatory assist devices (MCADs) are increasingly utilized independently of cardiac transplantation in the management of heart failure. Though MCAD use incorporates inherent mechanical risks, the inevitable onset of chronic anemia, with its associated morbidity and mortality, is also a significant concern. MCAD support has been correlated with elevated plasma levels of inflammatory cytokines TNF-alpha, IL-1beta, and IL-6, which have separately been found to inhibit erythropoietin (Epo)-induced erythrocyte (RBC) maturation. Previous analysis of hematological parameters for MCAD-supported patients concluded that an amplified inflammatory response impedes RBC proliferation and recovery from hemolytic anemia. Additional analysis may bolster this assertion. Hemoglobin concentration (HC), RBC distribution width (RDW), mean cell volume (MCV), and cardiac index were retrospectively analysed for 78 MCAD-supported patients implanted for greater than 30 days at the University of Arizona Health Sciences Center from 1996 to 2002. Analysis confirms that the HC, a conventional marker for anemia, declines with MCAD placement and remains below the clinically defined, minimum normal value. Inversely, the RDW rises above maximum normal measure, signifying an increased fraction of juvenile RBCs. The MCV remains unchanged and within normal limits, demonstrating adequate substrate for RBC formation. MCAD performance also stabilizes as adequate perfusion returns. These results further support our previously published conclusion that a sufficient response of erythropoiesis occurs in reaction to the onset of anemia by an increased production of immature RBCs. However, the cells never fully mature and join circulation. The patient's inflammatory cytokine response to the implanted device most likely mediates the chronic MCAD-induced anemia by inhibition of Epo effects.

Red Blood Cell Hemolysis and Suppression of Erythropoiesis Strongly Upregulate mRNA for Iron Binding Lipocalin (NGAL/24p3) in the Liver.

A member of the lipocalin family of proteins, NGAL/24p3, was demonstrated to bind iron and was suggested to participate in a non-transferrin dependent iron transport mechanism capable to deliver iron to the cytoplasm (Kaplan 2002, Yang et al. 2003). Therefore, we have studied mRNA for NGAL/24p3 levels in the liver tissue during its loading with iron released from senescent and damaged red blood cells. Red blood cell hemolysis was induced in mice by administration of phenylhydrazine (PHZ). Suppression of iron reutilization for erythropoiesis was achieved by a total body sublethal irradiation (5 Gy). Samples of liver tissue were collected 16 hrs or 48 hrs after PHZ and 40 hrs after irradiation. Combined treatment consisted from irradiation followed by PHZ administration 40 hrs later. The irradiation suppressed 24 hrs incorporation of 59Fe into blood from 46,5 % in controls to 1.2 % in irradiated mice, indicating a significant suppression of erythropoiesis. PHZ administration alone decreased hematocrit from 44.7 % to 38.7 %, reflecting degree of the red blood cell hemolysis. The combined treatment by irradiation and PHZ resulted in the elevation of the liver iron content from 43.8 to 106.7 micrograms/g wet tissue 16 hours after PHZ, indicating a significant loading of the liver tissue with iron. All these treatments increased mRNA for NGAL/24p3 levels as determined by real-time PCR, significantly. After the combined treatment the increase reached almost three orders of magnitude. We further compared the response of NGAL/24p3 mRNA to the response of hepcidin and transferrin-1 receptor (TfR-1) mRNAs, both known to be sensitive to the liver iron content. Hepcidin mRNA increased significantly after the treatment with irradiation, PHZ, or combination of irradiation and PHZ but the increase was less pronounced compared to that of NGAL/24p3 mRNA. TfR-1 mRNA significantly decreased 48 hours after the combined treatment only. As an indicator of the acute phase response, the mRNA for interleukin-6 was determined and it did not change after the treatments used. The results demonstrate that mRNA for the putative iron transport molecule NGAL/24p3 was strongly upregulated by experimental maneuvers that lead to accumulation of iron in the liver tissue.