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Query: UMLS:C0039730 (thalassemia)
 10,305 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The ferritin concentration in peripheral blood lymphocyte extracts was measured in 10 normal subjects, 7 patients with homozygous beta-thalassaemia, and 5 patients with iron-deficiency anaemia. The mean intracellular ferritin content was found increased in beta-thalassaemia and reduced in iron-deficient patients. Incubation of mononuclear cells in phytohaemagglutinin medium led to an increase of DNA synthesis concomitant with an increased number of lymphocytes bearing transferrin receptor and interleukin-2 receptor as measured by immunofluorescent technique. Although there was an immunological impairment of lymphocytes in patients with either iron depletion or iron loading compared to normal subjects, their ability to express transferrin receptor and interleukin-2 receptor on their cell surface was normal.
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PMID:Expression of cell-surface transferrin receptor following in vitro stimulation of peripheral blood lymphocytes in patients with beta-thalassaemia and iron-deficiency anaemia. 232 91

Clinical data suggest that in beta-thalassemia-intermedia patients, higher levels of circulating fetal hemoglobin (HbF) are associated with greater disease severity at comparable degrees of anemia. We assessed the influence of the amount of circulating HbF on serum erythropoietin (s-Epo) levels and on serum transferrin receptor, a measure of erythropoiesis, in 30 beta-thalassemia-intermedia patients. Twenty-four showed more than 40% HbF (21 of whom with beta (0)-thalassemia) and 6 presented lower HbF levels (beta(+)-thalassemia). The two groups of patients did not differ in age (15.3 v 19 years, respectively) or degree of anemia (Hb = 8.8 g/dL in both groups). Log (s-Epo) was correlated inversely with Hb (r = -0.47; P < .01), and directly with HbF (r = .55; P < .001). Multivariate regression analysis showed that Hb and HbF were independently correlated with s-Epo levels. High-HbF patients had greater s-Epo values at the same Hb level than low-HbF patients. Considering that iron-deficiency anemia control patients represented the predicted physiologic response of s-Epo to anemia, the observed/predicted s-Epo ratio in low-HbF thalassemic patients was no different from controls, but was increased in the high-HbF group. High-HbF patients also showed an expansion of erythropoiesis as much as four to nine times the normal value at the same Hb level as low-HbF patients. We conclude that HbF exerts an independent regulatory effect on erythropoietin production and erythropoiesis that is detectable only when HbF levels exceed 40%.
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PMID:Serum erythropoietin and erythropoiesis in high- and low-fetal hemoglobin beta-thalassemia intermedia patients. 750 55

Flow cytometric (FCM) immunophenotyping of peripheral blood from thalassemia patients presents technical difficulties because of the high proportion of immature red cells. The combination of forward scatter (FSC) and side scatter (SSC) with fluorescence associated with human leukocyte antigen/monocyte antigen (CD45/CD14) was unable to identify the lymphocyte population in thalassemia patients; therefore, it was necessary to exclude immature red cells to analyze lymphocyte subsets in these patients. A simultaneous three-color FCM method was developed, with the basis that transferrin receptor (CD71) or glycophorin A (glyco A) is present on all immature red cells, but is not expressed on CD45 positive leukocytes. In this study, the lymphocyte population was identified by gating out unwanted cell populations using the FSC/CD71-fluorescein isothiocyanate (FITC), FSC/glyco A-FITC, or FSC/CD45-peridinin chlorophyll protein (PerCP) profiles. The CD71-FITC negative cells, glyco A-FITC negative cells, or CD45-PerCP positive cells were identified, then analyzed on the basis of FSC/SSC to allow any remaining non-lymphocyte cells in FSC/SSC gate to be excluded. The cells in FSC/SSC gate were then analyzed using other irrelevant two-color antibodies. Of the three gating strategies, CD45-PerCP and glyco A-FITC methods are better than the CD71-FITC gating method. Both methods markedly increase the purity of lymphocytes in the analysis gate. Either method is easy, straightforward, requires a six-tube set of reagent tubes, and provides a reliable method for immunophenotyping lymphocyte subsets in preparations containing a large percentage of non-lymphoid cells.
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PMID:Flow cytometric immunophenotyping of lymphocyte subsets in samples that contain a high proportion of non-lymphoid cells. 753 76

In the management of beta-thalassaemia major, different transfusion schemes are employed with baseline haemoglobin levels ranging from 8 to over 12 g/dl. We studied the relationship between transfusion regimen and suppression of erythropoiesis in 52 patients with beta-thalassaemia major whose mean pretransfusion haemoglobin levels ranged from 8.6 to 10.9 g/dl. Multiple, regression analysis showed that serum transferrin receptor was the parameter more closely related to mean pretransfusion haemoglobin (r = -0.77, P < 0.001). As measured through serum transferrin receptor, erythroid activity was 1-2 times normal for pretransfusion haemoglobin levels between 10 and 11 g/dl. 1-4 times normal for levels from 9 to 10 g/dl, and 2-6 times normal for levels from 8.6 to 9 g/dl. Mean pretransfusion haemoglobin was also inversely related to serum erythropoietin (r = -0.72, P < 0.001), whereas it showed no or a weak relationship with Hb F, reticulocyte count, or circulating nucleated red cell count. This study suggests that serum transferrin receptor is a reliable indicator of suppression of erythropoiesis in beta-thalassaemia major. On the basis of our findings, pretransfusion haemoglobin values of < or = 9 g/dl should be adopted with caution, because these levels can be associated with an insufficient inhibition of erythroid marrow expansion. However, a transfusion programme, with a baseline haemoglobin of 9-10 g/dl, may provide enough suppression of erythropoiesis and allow a reduction in blood consumption as compared with the classic hyper- or supertransfusion schemes. Since fixed haemoglobin levels may not be the best target for transfusion treatment in all thalassaemic patients, assay of serum transferrin receptor may be helpful for individualizing the transfusion regimens.
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PMID:Relationship between transfusion regimen and suppression of erythropoiesis in beta-thalassaemia major. 773 44

High total haemoglobin levels in homozygous sickle cell (SS) disease are a risk factor for painful crises, avascular necrosis of the femoral head, proliferative sickle retinopathy, and the acute chest syndrome. Since lowering the haemoglobin level may ameliorate these features, understanding the determinants of total haemoglobin may be of practical importance. A range of possible determinants including red cell characteristics, reticulocytes, serum iron, transferrin saturation, serum ferritin, alpha thalassaemia status, red cell mass and plasma volume, oxygen affinity, red cell survival, transferrin receptor and erythropoietin levels have been measured in 62 patients selected to provide a range of total haemoglobin and fetal haemoglobin levels. There were weak negative associations of haemoglobin with mean cell volume and mean cell haemoglobin concentration, strong negative associations with proportional reticulocyte counts, oxygen affinity, plasma volume, serum transferrin receptors, and erythropoietin levels and strong positive associations with red cell mass. Weighted analysis suggested that the statistically independent determinants of haemoglobin level were alpha thalassaemia, sex, red cell mass/body weight, plasma volume/body weight, fetal haemoglobin, and red cell count. The apparent contributions of red cell survival, P50, reticulocyte count, serum transferrin receptor and erythropoietin levels were explained by the effects of these other variables. The independent determinants as a group explained 91% of the variation in haemoglobin level.
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PMID:Determinants of haemoglobin level in steady-state homozygous sickle cell disease. 856 87

Systemic-onset juvenile chronic arthritis (SoJCA) is associated with high levels of circulating interleukin-6 (IL-6) and is frequently complicated by severe microcytic anemia whose pathogenesis is unclear. Therefore, we studied 20 consecutive SoJCA patients with hemoglobin (Hb) levels <12 g/dL, evaluating erythroid progenitor proliferation, endogenous erythropoietin production, body iron status, and iron supply for erythropoiesis. Hb concentrations ranged from 6.5 to 11.9 g/dL. Hb level was directly related to mean corpuscular volume (r = .82, P < .001) and inversely related to circulating transferrin receptor (r = -.81, P < .001) suggesting that the severity of anemia was directly proportional to the degree of iron-deficient erythropoiesis. Serum ferritin ranged from 18 to 1,660 microgram/L and was unrelated to Hb level. Bone marrow iron stores wore markedly reduced in the three children investigated, and they also showed increased serum transferrin receptor and normal-to-high serum ferritin. All 20 patients had elevated IL-6 levels and normal in vitro growth of erythroid progenitors. Endogenous erythropoietin (epo) production was appropriate for the degree of anemia as judged by both the observed to predicted log (serum epo) ratio 10.95 +/- 0.12) and a comparison of the serum epo-Hb regression found in these subjects with that of thalassemia patients. Multiple regression analysis showed that serum transferrin receptor was the parameter most closely related to hemoglobin concentration: variation in circulating transferrin receptor explained 61% of the variation in Hb level (P < .001). In 10 severely anemic patients, amelioration of anemia following intravenous iron administration resulted in normalization of serum transferrin receptor. Defective iron supply to the erythron rather than blunted epo production is the major cause of the microcytic anemia associated with SoJCA. A true body-iron deficiency caused by decreased iron absorption likely complicates long-lasting inflammation in the most anemic children, and this can be recognized by high serum transferrin receptor levels. Although oral iron is of no benefit, intravenous iron saccharate is a safe and effective means for improving iron availability for erythropoiesis and correcting this anemia. Thus, while chronically high endogenous IL-6 levels do not appear to blunt epo production, they are probably responsible for the observed abnormalities in iron metabolism. Anemia of chronic disease encompasses a variety of anemic conditions whose peculiar features may specifically correlate with the type of cytokine(s) predominantly released.
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PMID:Defective iron supply for erythropoiesis and adequate endogenous erythropoietin production in the anemia associated with systemic-onset juvenile chronic arthritis. 863 55

Using the IgG fraction of an antiserum against cord red blood cell (RBC) membranes (F-IgG), antigenic properties of RBC of newborns (n = 24) and patients suffering from anemia (n = 46) [either due to beta-thalassemia intermedia (n = 37) or hemorrhage (n = 9)] as compared to those of normal adults (n = 18) were examined with fluorescence microscopy, flow cytometry and radioimmunoassays (RIA). With fluorescence microscopy and flow cytometry 1.01 +/- 0.31 and 0.82 +/- 0.28% (mean +/- SD), respectively, of cord RBC and 0.79 +/- 0.31 and 0.53 +/- 0.28% of RBC from anemic patients reacted with F-IgG. RBC of normal adults showed virtually no F-IgG reactivity. In anemic patients there was a good correlation between the percent of F-IgG-reactive cells and the percent of reticulocytes, although the former were only two thirds of the latter; the ratio of F-IgG-reactive cells to reticulocytes was higher in posthemorrhagic anemia than in thalassemia. Moreover, double stainings revealed that the majority of F-IgG-reactive RBC were at the reticulocyte stage (80%), and coexpressed transferrin receptor (96%). Furthermore, the F-IgG-positive RBC correlated inversely with Hb levels. When RIA was employed, F-IgG binding to RBC of anemic patients and newborns was similar and considerably and significantly higher than that to RBC from healthy adults. The results demonstrate the reappearance in certain forms of anemia of F-IgG-reactive RBC, which are likely to represent a subpopulation of reticulocytes.
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PMID:Red blood cells expressing fetal antigens: their presence in adults with certain forms of anemia. 867 58

In this study we determined the levels of circulating soluble transferrin receptor (sTfR) in six untransfused and two transfused patients affected by beta-thalassemia intermedia during low-dose rHuEPO administration. While the majority of the untransfused patients showed a temporary increment during the first month of treatment, a higher and enduring increase in sTfR concentration was observed in the two transfused patients until rHuEPO was discontinued. The transfused patients showed a significant increase in the reticulocyte index together with the rise in sTfR and an improvement of the anemia, as evidenced by the decrease in their transfusional requirement. These data suggest that basal erythropoietic activity is one of the main causes of differences in responsiveness to low doses of rHuEPO given in thalassemia intermedia.
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PMID:Serum transferrin receptor levels in patients with thalassemia intermedia during rHuEPO administration. 890 Aug 49

Serum erythropoietin (sEpo) concentration is primarily related to the rate of renal production and, under the stimulus of hypoxia, increases exponentially as hemoglobin (Hb) decreases. Additional factors, however, appear to influence sEpo, and in this work, we performed studies to evaluate the role of the red blood cell precursor mass. We first compared the relationship of sEpo with Hb in patients with low versus high erythroid activity. The first group included 27 patients with erythroid aplasia or hypoplasia having serum transferrin receptor (sTfR) levels < 3 mg/L (erythroid activity < 0.6 times normal), while the second one included 28 patients with beta-thalassemia intermedia having sTfR levels > 10 mg/L (erythroid activity > 2 times normal). There was no difference between the two groups with respect to Hb (8.3 +/- 1.6 v 8.0 +/- 1.3 g/dL, P > .05), but sEpo levels were notably higher in patients with low erythroid activity (1,601 +/- 1,542 v 235 +/- 143 mU/mL, P < . 001). In fact, multivariate analysis of variance (ANOVA) showed that, at any given Hb level, sEpo was higher in patients with low erythroid activity (P < .0001). Twenty patients undergoing allogeneic or autologous bone marrow transplantation (BMT) were then investigated. A marked increase in sEpo was seen in all cases at the time of marrow aplasia, disproportionately high when compared with the small decrease in Hb level. Sequential studies were also performed in five patients with iron deficiency anemia undergoing intravenous (IV) iron therapy. Within 24 to 72 hours after starting iron treatment, marked decreases in sEpo (up to one log magnitude) were found before any change in Hb level. Similar observations were made in patients with megaloblastic anemia and in a case of pure red blood cell aplasia. These findings point to an inverse relationship between red blood cell precursor mass and sEpo: at any given Hb level, the higher the number of red blood cell precursors, the lower the sEpo concentration. The most likely explanation for this is that sEpo levels are regulated not only by the rate of renal production, but also by the rate of utilization by erythroid cells.
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PMID:Red blood cell precursor mass as an independent determinant of serum erythropoietin level. 949 Jul 1

Thalassemia is an inherited hematological disorder which can generally be classified according to the affected globin imbalance (alpha- or beta-globin) into two main types, i.e. alpha-thalassemia and beta-thalassemia, respectively. There is a wide range of cellular abnormalities associated with thalassemic erythrocytes such as hypochromia, microcytosis, reduced cellular deformability and membrane oxidative damage. The red cell abnormalities lead to premature destruction with marrow erythroid hyperplasia and ineffective erythropoiesis. The abnormalities in thalassemic red blood cells have been found along the erythroid differentiation pathway other than the mature stage as previously shown in bone marrow erythroid precursors and in reticulocytes, the penultimate stage of erythroid differentiation. However, there is a lag in our understanding of the more primitive erythroid stages due to the difficult and hazardous marrow aspiration and heterogeneity of cells derived. We have utilized a novel method of Two-Phase Liquid Culture (TPLC) of beta-thalassemia/HbE erythroid precursors instead of conventional semisolid culture. This type of liquid culture can given higher cell yield with quite synchronous cell differentiation stages and easily be applied for other cellular analytical techniques. The peripheral blood mononuclear cells (PBMC) obtained from non-splenectomized and splenectomized beta-thalassemia/HbE patients were first cultured in medium supplemented with 5637 conditioned medium for a 6-day period (phase I) and then transferred to medium supplemented with recombinant human erythropoietin to allow the terminal differentiation of erythroid precursors (phase II). During the phase I or II, the cultured cells were periodically sampled to determine the cell number, cytocentrifuged on glass slides and stained with Wright stain for morphological assessment of their differentiation stages and analyzed flow cytometrically by staining with fluoresceinated anti-transferrin receptor (anti-CD71) and R-phycoerythrin-conjugated anti-glycophorin A. After assessment by flow cytometry, the remaining stained cells were cytocentrifuged on glass slides and photographed by a fluorescent microscope and a laser scanning confocal microscope. The results of morphological assessment, flow cytometric analysis and microscopic pictures will be presented.
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PMID:An in vitro study on thalassemic erythroid precursors in liquid culture. 964 Jun 5


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