Pathophysiological classification of acquired bone marrow failure based on quantitative assessment of erythroid function

Bone marrow failure encompasses a broad spectrum of disorders including aplastic, dysmyelopoietic and myelophtisic anemias. In the present study, these anemias were characterized according to the degree of erythroid proliferation and efficiency of erythropoiesis. Total erythropoietic activity was evaluated in 43 patients by measuring the erythron transferrin uptake (ETU). It averaged 20% of basal (range 3-43%) in 13 patients with severe aplastic anemia, 75% of basal (range 60-103%) in 3 patients with extensive bone marrow infiltration by neoplastic cells, 131% of basal (range 50-217%) in 16 patients with refractory anemia, and 452% of basal (range 63-720) in 11 patients with idiopathic refractory siderobastic anemia. Respective efficiencies of erythropoiesis were 74% in aplastic anemia, 70% with bone marrow infiltration, 46% in refractory anemia, and 14% in sideroblastic anemia. Based on the ETU, patients could be categorized into absolute marrow failure, relative marrow failure, and adequate erythropoietic response to anemia. This simple determination of proliferating activity of the erythroid marrow can provide useful information on the pathophysiology of marrow failure and a basis for the selection of therapeutic approaches.     

Ferrokinetic evaluation of erythropoiesis in patients with myelodysplastic syndromes

Erythropoietic activity in patients with myelodysplastic syndrome (MDS) was evaluated by ferrokinetic measurements. Since the conventional plasma iron turnover of MDS patients increased with plasma iron levels after multiple blood transfusions, erythron transferrin uptake was chosen as a parameter of erythroid marrow activity. Although a correlation was shown between plasma iron level and plasma iron turnover (r = 0.50, 0.01 less than p less than 0.02), no correlation existed between the plasma iron level and erythron transferrin uptake (r = 0.25, p greater than 0.1). Erythron transferrin uptake, independent of plasma iron, was significantly higher in MDS patients than in normal subjects (110.6 +/- 67.6 and 67.6 +/- 18.8 mumol/l/dl, respectively; 0.01 less than p less than 0.02). An increased erythropoiesis occurring concomitantly with morphologically normal or increased erythroid cellularity was demonstrated in patients with MDS. The measurement of erythron transferrin uptake might be valuable as an accurate expression of erythroid activity in the hyperferremic state.     

Serum transferrin receptor as a new index of erythropoiesis

Serum transferrin receptors were measured by a sandwich radioimmunoassay procedure in patients with iron deficiency anemia, autoimmune hemolytic anemia and aplastic anemia. The mean circulating transferrin receptor concentration of normal subjects and patients with iron deficiency anemia, autoimmune hemolytic anemia and aplastic anemia are 253 +/- 82 ng/mL, 730 +/- 391 ng/mL, 1,426 +/- 1,079 ng/mL, and 182 +/- 39 ng/mL, respectively. The values for those with iron deficiency anemia and autoimmune hemolytic anemia were significantly higher than that of normal controls and the values for those with aplastic anemia were lower than that of normal controls. After iron supplementation in iron deficiency anemia, the serum transferrin receptor values increased twofold over those of pretreatment values. This increase parallels an increase in peripheral reticulocytes. Therefore, the number of circulating transferrin receptors in anemic patients may reflect the level of bone marrow erythropoiesis and is a potentially useful new index for red cell production.     

Erythropoietin activity in the serum of beta thalassemic patients

Serum erythropoietic activity was determined in 32 patients with beta thalassemia major and intermedia. Quantitation was performed by an in vitro bioassay using rabbit erythroid precursor cells (CFU-E) either by colony assay or by 3H-thymidine uptake. 20 polytransfused beta-thalassemic major patients had erythropoietic activity (mean 89.3 +/- 36 milliunits/ml) which was not significantly different (p greater than 0.2) from normal individuals (51.3 +/- 32 milliunits/ml). 12 untransfused patients with beta thalassemia intermedia were found to have comparable serum erythropoietic activity (p greater than 0.01). These levels were much lower than those found in patients with aplastic anemia who had a comparable degree of anemia. We have shown that the low EPO activity in thalassemic patients was not due to experimental conditions (excess of ferritin, low transferrin) nor to specific inhibitors appearing in this disease. No correlation was found between the erythropoietic activity and sex or other clinical parameters of the patients such as severity of the anemia, splenectomy, iron chelation or transfusion therapy. 4 young thalassemic children (1-2 yr of age) studied had high erythropoietic activity ranging from 661 to 5793 milliunits/ml--significantly different from normal children of the same age. It is suggested, therefore, that a decrease in serum erythropoietin levels develops during the course of the disease.     

Transferrin saturation, plasma iron turnover, and transferrin uptake in normal humans

The relationship between plasma iron, transferrin saturation, and plasma iron turnover was studied in 53 normal subjects whose transferrin saturation varied between 17% and 57%, in 25 normal subjects whose transferrin saturation was increased by iron infusion to between 67% and 100%, and in five subjects with early untreated idiopathic hemochromatosis whose transferrin saturation was continually elevated to between 61% and 86%. The plasma iron turnover of all of these subjects ranged from 0.45 to 1.22 mg/dL whole blood/d. The mean values for the above-mentioned three groups were 0.71 +/- 0.17, 1.01 +/- 0.11, and 1.01 +/- 0.13 mg/dL whole blood/d, respectively. Most of this variation, estimated at 72% by regression analysis, was due to a direct relationship between transferrin saturation and plasma iron turnover. This effect was attributed to a competitive advantage of diferric over monoferric transferrin in delivering iron to tissues. This was confirmed by the demonstration of a more rapid clearance of diferric as compared to monoferric transferrin in an additional group of eight normal subjects. Calculations were made of the amount of transferrin reacting with membrane receptors per unit time. Allowance was made for the noncellular (extravascular) exchange and for the 4.2:1 preference of diferric over monoferric transferrin demonstrated in vitro. The amount of iron-bearing transferrin leaving the plasma to bind to tissue receptors for 53 subjects with a transferrin saturation between 17% and 57% was 71 +/- 13; for 25 subjects with a saturation from 67% to 100%, 72 +/- 12; and for five subjects with early idiopathic hemochromatosis, 82 +/- 11 mumol/L whole blood/d. There were no significant differences among these groups. These studies indicate that while the number of iron atoms delivered to the tissues increases with increasing plasma iron and transferrin saturation, the number of iron-bearing transferrin molecules that leave the plasma per unit time to bind to tissue receptors is relatively constant and within the limits studied, independent of transferrin saturation.     

The soluble transferrin receptor in dysplastic erythropoiesis in myelodysplastic syndrome

OBJECTIVES: In individuals without iron deficiency, the soluble transferrin receptor (sTfR) directly reflects the erythropoietic activity. This study investigated sTfR concentrations in ineffective, dysplastic erythropoiesis in myelodysplastic syndrome (MDS). METHODS: To exclude influences of other myeloid cells on sTfR, only patients with refractory anemia (RA), refractory anemia with ringed sideroblasts (RARS) and 5q(-) syndrome were included. sTfR was measured nephelometrically (normal range 0.81-1.75 mg/L). RESULTS: Thirty-four untreated MDS patients (RA = 14, RARS = 10, 5q(-) syndrome = 10) were enrolled and analysed. The mean sTfR value of all MDS patients (1.30 +/- 0.8 mg/L, range 0.2-3.8) did not differ from our control group. In 5q(-) syndrome, the mean sTfR concentration (0.80 +/- 0.5 mg/L) was significantly lower than in RA (1.32 +/- 0.4 mg/L, P = 0.02) and RARS (1.75 +/- 1.1 mg/L, P = 0.03). Subdividing MDS according to their amount of erythroid mass in bone marrow a significant difference of sTfR between patients with decreased (0.70 +/- 0.4 mg/L), normal (1.32 +/- 0.4 mg/L) and increased (2.06 +/- 0.9 mg/L) erythropoiesis was observed. MDS patients with sTfR values below the reference range of 0.81 mg/L required transfusions in 90% of cases and showed higher erythropoietin levels compared to MDS patients with sTfR levels > or =0.81 mg/L (P = 0.01). There was a good agreement between sTfR and the amount of polychromatic erythroblasts observed (r = 0.68, P < 0.001). CONCLUSION: In conclusion, the serum concentration of sTfR reflects erythropoietic activity in MDS, but it is in particular determined by the degree of erythroid maturation and the severity of ineffective erythropoiesis. Low sTfR values in MDS are associated with a reduced, poorly differentiated erythropoiesis and requirement of blood transfusions.     

Serum non-transferrin-bound iron in beta-thalassaemia major patients treated with desferrioxamine and L1

Non-transferrin-bound iron (NTBI) in plasma is toxic due to its ability to participate in free radical formation with resultant peroxidation and damage to cell membranes and other biomolecules. NTBI concentration was determined in serum in 12 normal volunteers and in 52 patients with beta-thalassaemia major by a modification of the method described by Singh et al (1990). There was no detectable NTBI in normal individuals. In the patients NTBI values ranged from -1.5 to 9.0 mumol/l (mean +/- SD: 3.6 +/- 2.3). The patients' serum ferritin concentrations ranged from 207 to 11,400 micrograms/l (2674 +/- 2538), total serum iron from 20 to 61 mumol/l (39.5 +/- 9.6) and transferrin saturation from 44 to 110% (84.5 +/- 13.8). The NTBI correlated significantly with serum ferritin (r = 0.467, P < 0.001), total serum iron (r = 0.608, P < 0.001) and transferrin saturation (r = 0.481, P < 0.005). When patients were grouped according to their compliance with desferrioxamine (DFX) therapy, the good compliers had significantly lower NTBI concentrations compared to the poor compliers (poor: 5.4 +/- 1.8 mumol/l v good: 2.7 +/- 1.7 mumol/l, P < 0.001). There was also a significant difference between the level of NTBI and whether or not the patients had complications of iron overload (5.2 +/- 1.7 mumol/l v 2.9 +/- 1.6 mumol/l, P < 0.001). During this study 10 patients were entered into a trial of the oral iron chelator 1,2- dimethyl-3-hydroxypyrid-4-one (L1). Their NTBI values were observed during the first 6 months of the trial and showed a significant fall (paired t-test: P = 0.007). These results suggest that the level of NTBI may prove helpful in assessing the efficiency of chelation in patients with transfusion dependent anaemia and help to predict organ damage.     

Erythroblast transferrin receptors and transferrin kinetics in iron deficiency and various anemias

To clarify the role of transferrin receptors in cases of altered iron metabolism in clinical pathological conditions, we studied: number of binding sites; affinity; and recycling kinetics of transferrin receptors on human erythroblasts. Since transferrin receptors are mainly present on erythroblasts, the number of surface transferrin receptors was determined by assay of binding of 125I-transferrin and the percentage of erythroblasts in bone marrow mononuclear cells. The number of binding sites on erythroblasts from patients with an iron deficiency anemia was significantly greater than in normal subjects (p less than 0.01). Among those with an aplastic anemia, hemolytic anemia, myelodysplastic syndrome, and polycythemia vera compared to normal subjects, there were no considerable differences in the numbers of binding sites. The dissociation constants (Kd) were measured using Scatchard analysis. The apparent Kd was unchanged (about 10 nmol/L) in patients and normal subjects. The kinetics of endocytosis and exocytosis of 125I-transferrin, examined by acid treatment, revealed no variations in recycling kinetics among the patients and normal subjects. These data suggest that iron uptake is regulated by modulation of the number of surface transferrin receptors, thereby reflecting the iron demand of the erythroblast.     

Defective iron supply for erythropoiesis and adequate endogenous erythropoietin production in the anemia associated with systemic-onset juvenile chronic arthritis

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.     

Microcytic anemia and hepatic iron overload in a child with compound heterozygous mutations in DMT1 (SCL11A2)

Divalent metal transporter 1 (DMT1) mediates apical iron uptake in duodenal enterocytes and iron transfer from the transferrin receptor endosomal cycle into the cytosol in erythroid cells. Both mk mice and Belgrade rats, which carry an identical DMT1 mutation, exhibit severe microcytic anemia at birth and defective intestinal iron use and erythroid iron use. We report the hematologic phenotype of a child, compound heterozygote for 2 DMT1 mutations, who was affected by severe anemia since birth and showed hepatic iron overload. The novel mutations were a 3-bp deletion in intron 4 (c.310-3_5del CTT) resulting in a splicing abnormality and a C>T transition at nucleotide 1246(p. R416C). A striking reduction of DMT1 protein in peripheral blood mononuclear cells was demonstrated by Western blot analysis. The proband required blood transfusions until erythropoietin treatment allowed transfusion independence when hemoglobin levels between 75 and 95 g/L (7.5 and 9.5 g/dL) were achieved. Hematologic data of this patient at birth and in the first years of life strengthen the essential role of DMT1 in erythropoiesis. The early onset of iron overload indicates that, as in animal models, DMT1 is dispensable for liver iron uptake, whereas its deficiency in the gut is likely bypassed by the up-regulation of other pathways of iron use.     

Abnormalities in the regulation of erythropoiesis by bone marrow fibroblasts in aplastic anemia

The influence of bone marrow fibroblasts in healthy subjects and patients with aplastic anemia on normal erythroid colony formation was studied using the methylcellulose method. These fibroblasts were treated with methylprednisolone as well. Bone marrow fibroblasts of healthy subjects and patients with aplastic anemia, and the supernatant of their conditioned medium significantly inhibited normal erythroid colony formation. A significantly marked inhibition of normal erythroid colony formation was observed of bone marrow fibroblasts (or the conditioned medium) of the aplastic anemia, when compared with that of the bone marrow of healthy subject fibroblasts (or the conditioned medium). By treating both groups of the bone marrow fibroblasts with methylprednisolone the inhibition was slightly improved. From the above experimental results, it was suggested that the bone marrow fibroblasts and the conditioned medium inhibited normal erythroid colony formation through humoral factors secreted by the fibroblasts, and through contact between the fibroblasts and erythroid colony formation cells.     

Serum levels of erythropoietin and soluble transferrin receptor in the course of pregnancy in non beta thalassemic and beta thalassemic women

BACKGROUND AND OBJECTIVES: In non-thalassaemic women serum erythropoietin (Epo) level increases during pregnancy, whereas that of soluble transferrin receptor (STFR) drops slightly in the first two trimesters to attain the original values in the third trimester. In this study the time-course of these two parameters was explored in b-thalassemic and non-b-thalassemic women, both pregnant and not. DESIGN AND METHODS: Two hundred and fifty-seven women were studied: 64 non-b-thalassemic, non-pregnant women made up the reference group, 89 were non-b-thalassemic pregnant women, and 104 were b-thalassemic pregnant or non-pregnant women. The full blood count, hemoglobin levels and iron status (serum iron and serum ferritin levels) were explored by traditional methods. Serum Epo and STFR levels were measured with standard commercial kits. RESULTS: In non-b-thalassemic women the mean non-pregnant Epo level (10.95 +/-4. 7 mU/mL) increased in the first trimester (17.12 +/-5.18 mU/mL), was stationary in the second, and increased again in the third (31. 43+/-14.13 mU/mL). STFR mean value dropped in early pregnancy from 2. 40+/-0.72 mg/L to 1.78 +/- 0.64 mg/L, and then returned to the original value (2.38 +/- 0.94 mg/L). In b-thalassemic women the mean non-pregnant Epo level (15.00 +/-6.56 mU/mL) was higher than in non-thal non-pregnant women. During pregnancy it progressively increased to 35.60+/-25.46 mU/mL. STFR (non-pregnant level 3.37+/-1. 07 mg/L) gradually increased throughout the whole gestation period and by the third trimester its level was markedly higher than that of non-b-thal women at the corresponding stage of gestation (9. 41+/-5.39 mg/L vs 2.40+/-0.72 mg/L). INTERPRETATION AND CONCLUSIONS: The STFR level changed to different extents in non-b-thal and b-thal women during their pregnancies. In the former STFR markedly decreased in early pregnancy; in the latter it showed no decrease in the first trimester, increased in the second and reached very high values in the third. This time course is likely to be the consequence of erythroid bone marrow hyperplasia and hyperactivity, which are usually present in all b-thalassemic patients and in heterozygous carriers as well.     

Erythroblast iron metabolism and serum soluble transferrin receptor values in the anemia of rheumatoid arthritis

OBJECTIVES: We have investigated in vitro erythroblast iron metabolism in the anemia of rheumatoid arthritis (RA). We also have examined the results in relation to bone marrow iron status in an attempt to explain the reported difference between serum soluble transferrin receptor (sTfR) values in anemia of chronic disease (ACD) and iron deficiency anemia (IDA) in patients with RA. METHODS: Bone marrow was examined in 29 anemic patients with RA, 9 healthy volunteers, and 6 patients with simple IDA. High purity erythroblast fractions were prepared from these bone marrow samples. Erythroblast surface TfR expression and iron uptake was assessed in vitro using (125)I-transferrin (Tf) and (59)Fe-Tf, respectively. The efficiency of erythroblast surface TfR function for Tf-iron uptake was determined by relating total iron uptake at 4 hours to surface TfR number. Serum sTfR values were measured for the RA anemia group, which was subdivided as RA-ACD (marrow iron present) or RA-IDA (marrow iron absent) on the basis of visible reticuloendothelial (RE) marrow iron stores. RESULTS: High purity (87 +/- 5%) erythroblast fractions were obtained from 35 of the 44 marrow samples. Erythroblasts obtained from patients with simple IDA showed a significant increase in surface TfR expression (P = 0.0003) and Tf-iron uptake (P = 0.001). RA anemia also led to a significant increase in erythroblast Tf-iron uptake (P = 0.016). This increase was not associated with an increase in surface TfR expression (P = 0.5), but was seen to occur as a result of a significant increase in the efficiency of surface TfR for Tf-iron uptake (P = 0.027). Within the RA anemia group, the increase in erythroblast Tf- iron uptake at 4 hours was more evident for RA-IDA (3.96 +/- 1.73 versus 1.66 +/- 0.66; P = 0.03) than for RA-ACD (2.69 +/- 1.18 versus 1.66 +/- 0.66; P = 0.057). This additional erythroblast response to absent RE iron stores led to a highly significant difference in serum sTfR values between RA-IDA and RA-ACD (40.2 +/- 14.0 versus 23.9 +/- 5.3 nmoles/liter; P = 0.001) CONCLUSIONS: An increase in erythroblast surface TfR efficiency for Tf-iron uptake compensates for the low plasma iron levels associated with anemia in RA and helps to maintain RA erythroblast iron uptake. With adequate RE iron stores, this increased efficiency limits intracellular iron deprivation and consequently reduces the need to increase surface TfR expression. As a result, serum sTfR levels in RA-ACD remain within the normal range. RA erythroblasts, however, are still able to respond to any additional worsening of the iron supply caused by absent RE iron stores. This additional response causes the highly significant increase in serum sTfR values seen between RA-IDA and RA-ACD.     

Ret-Y a measure of reticulocyte size: a sensitive indicator of iron deficiency anemia

In this study the size of reticulocytes was measured, reticulocyte-Y (Ret-Y), to distinguish iron deficiency anemia from the anemia of chronic disease using a Sysmex XE2100 cell counter. We evaluated this parameter prospectively in 100 patients seen for the evaluation of anemia. A clinical diagnosis of iron deficiency anemia or anemia of chronic disease was made on the basis of a complete blood count, examination of the peripheral smear, and serum ferritin along with a history and physical examination. We analyzed the sensitivity and specificity of the Ret-Y in relationship to the clinical diagnosis. We also measured serum transferrin receptor levels to use as the gold standard laboratory test for iron deficiency against which we compared the Ret-Y. In 40 normal individuals with normal serum ferritin and transferrin receptor levels the mean Ret-Y was 1874 +/- 178 (1 SD). The mean Ret-Y in the anemia of chronic disease group (n=62) was 1722 +/- 162, not significantly different from normal. The mean Ret-Y value among iron-deficient patients (n=38), was 1407 +/- 136 (P <0.01 vs. the anemia of chronic disease group's Ret-Y value). Receiver operator curves showed that Ret-Y correlated closely to the serum transferrin receptor and was superior to the mean corpuscular volume, and ferritin level, in differentiating the type of anemia. The Ret-Y parameter has the highest overall sensitivity and specificity of the panel of tests routinely used in differentiating iron deficiency anemia from anemia of chronic disease.     

血清转铁蛋白受体对贫血患者鉴别诊断的临床意义

目的比较各项铁指标在慢性病贫血(ACD),缺铁性贫血(IDA)及ACD合并IDA中的变化规律,明确血清转铁蛋白受体(sTfR)的临床意义.方法设健康志愿者28例为对照组,同时设IDA组29例,ACD组 56例,分别进行血清铁(SI)、总铁结合力(TIBC)、运铁蛋白饱和度(TS)、血清铁蛋白(SF)及sTfR检测,并对26例慢性病患者做骨髓铁染色,根据sTfR值将ACD组分为(1)sTfR值正常组(ACD1组)27例(sTfR≤20.0 nmol/L ),(2)sTfR值升高组(ACD2组)29例(sTfR>20.0 nmol/L).结果 IDA组与其他各组相比,其中平均红细胞体积(68.0±11.3)fl为最小;SI、TS及SF值分别是(19.6±10.1) mg/L、(5.5±2.3)%和(4.3±2.8)μg/L,与对照组(81.7±30.6) mg/L、(27.0±12.0)%和(43.3±26.8) μg/L相比水平明显下降(P≤0.01);sTfR水平(67.2±40.3) nmol/L明显高于对照组(15.6±4.1) nmol/L,P≤0.01.ACD1组SF值(627.3±40.3) μg/L,明显高于其他各组(P≤0.01); SI(60.7±28.7) mg/L和TS(21.1±9.8)%与对照组差异无显著性(P>0.05),10例骨髓铁染色均无缺铁.ACD2组SF值(320.5±156.0) μg/L,高于对照组而低于ACD1组(P≤0.01),16例骨髓铁染色中14例显示铁缺乏,占88%.结论 sTfR值的升高有效地反映了体内铁缺乏状况,是诊断IDA更为敏感的指标,并且较少受慢性炎症性疾病的影响,可与ACD有效鉴别.     

Interferon is a mediator of hematopoietic suppression in aplastic anemia in vitro and possibly in vivo.

We have investigated interferon as a mediator of hematopoietic suppression in bone marrow failure. Interferon production by stimulated peripheral blood mononuclear cells from patients with aplastic anemia was significantly higher than that observed in controls; spontaneous interferon production by these cells was also high for more than half of aplastic anemia patients. Circulating interferon, not detectable in normal individuals, was detected in 10 of 24 patients. Interferon is a potent inhibitor of hematopoietic cell proliferation and, therefore, may be the mediator of suppression in many in vitro models employing patients' cells and sera. The possible pathogenic importance of interferon in aplastic anemia was suggested by an increase in hematopoietic colony formation in vitro after exposure of bone marrow cells to antiinterferon antisera (277 +/- 71% increase for patients compared to 1.6 +/- 1.6% for normal individuals). Interferon levels in the bone marrow sera of aplastic anemia patients were high (mean = 203 international units (IU)/ml, n = 8), even in comparison to circulating levels in the same patients. Normal bone marrow sera also contained measurable interferon but at lower levels (41 IU/ml, n = 16), indicating that interferon may be a normal bone marrow product. High concentration of bone marrow interferon, possibly due to abnormal immunologic activity or a reaction to virus infection of the bone marrow, may mediate hematopoietic suppression in aplastic anemia patients.     

The usefulness of serum transferrin receptor and ferritin for assessing anemia in rheumatoid arthritis: comparison with bone marrow iron study

OBJECTIVES: This study was aimed at investigating the usefulness of serum transferrin receptor (sTfR) and ferritin in anemic patients with rheumatoid arthritis (RA) compared with bone marrow storage iron and other tests for anemia. METHODS: Fifty-five anemic RA patients underwent anemia study. Bone marrow iron stain was performed in 18 patients. sTfR and serum ferritin levels were compared with bone marrow iron stores. RESULTS: (1) Mean sTfR concentration was 2.63+/-1.91 mg/L, (2) sTfR correlated with most indicators of anemia, (3) sTfR showed no correlation with CRP and ESR, whereas ferritin did, and (4) sTfR was higher in the "iron depleted" subgroup than in the "iron nondepleted" subgroup in bone marrow study. CONCLUSION: The measurement of sTfR and ferritin is useful in finding the cause of anemia in RA and is a possible substitute for invasive bone marrow iron study.     

Clinical paroxysmal nocturnal hemoglobinuria is the result of expansion of glycosyl-phosphatidyl-inositol-anchored protein-deficient clone in the condition of Deficient Hematopoiesis

Paroxysmal nocturnal hemoglobinuria (PNH) is an acquired, clonal hematopoietic stem cell disorder in which PIG-A, gene essential for the biosynthesis of the glycosyl-phosphatidyl-inositol (GPI) anchor, is somatically mutated. Absence of GPI-linked proteins from the surface of blood cells is characteristic of the PIG-A mutant (PNH) clone and is also accountable fo certain manifestations, such as intravascular hemolysis. It is unclear how the PNH clone expands and comes to dominate hematopoiesis. In this study, CD34+ cells--committed progenitors (colony-forming cells) representing immature hematopoietic stem cells--and reticulocytes representing the differentiated erythroid cells were quantitated in peripheral blood of patients with PNH. Compared with normal controls (n = 29), CD34+ cell levels were significantly lower in PNH patients who did not have preexisting aplastic anemia (AA) (n = 12) (2.47+/-1.23 versus 4.68+/-1.05 x 106/L, mean +/- standard error; P = .022). PNH patients with precedent aplastic anemia (AA+/PNH) showed markedly low CD34+ cell levels compared with normal control subjects (0.6+/-0.29 versus 4.68+/-1.05 x 10(6)/L; P = .0001). In addition, colony-forming cells from PNH patients were significantly decreased compared with those from normal volunteers (erythroid burst-forming units, 2.8+/-1.2 versu 25.6+/-6.2/5 x 10(5) mononuclear cells; P = .0006; and granulocyte/macrophage colony-forming units, 1.2+/-0.5 versus 13.3+/-3.0/ 5 x 10(5) mononuclear cells; P = .0006). These findings occur in both aplastic and hemolytic types of PNH, suggesting hematopoietic failure in PNH. On the contrary, the numbers of reticulocytes and the reticulocyte production index of PNH patients were significantly higher than those of normal persons and comparable to those from patients with autoimmune hemolytic anemia, indicating accelerating erythropoiesis in PNH. The degree of reticulocytosis correlated well with the proportion of CD59- (PNH) reticulocytes. All of the findings suggest that in the condition of deficient hematopoiesis, the PNH clone arising from the mutated hematopoietic stem cell expands and maintains a substantial proportion of the patient's hematopoiesis.     

A multicenter trial of antithymocyte globulin in aplastic anemia and related diseases

One hundred fifty patients with bone marrow failure were treated in three groups with antithymocyte globulin (ATG; Upjohn, Kalamazoo, MI) in a multicenter trial. Patients were assessed at 3, 6, and 12 months after initiation of treatment by three criteria: transfusion independence, clinical improvement, and blood counts. Group I consisted of 77 patients with acute severe aplastic anemia, randomized to receive either ten or 28 days of ATG. There was no significant difference between the two arms of this protocol: 47% of all patients were clinically improved and 31% were transfusion independent at 3 months. Of the severely affected patients, 27% died before 3 months; most deaths occurred early in treatment. Factors associated with survival in severely affected patients included male sex, age less than 40 years, absolute neutrophil count greater than 200/microL, and idiopathic etiology. Neutrophil counts generally increased by 8 weeks after treatment, but patients continued to show improvement to 1 year posttreatment. In Group II, 44 patients with moderate or chronic severe aplastic anemia were randomized to receive either ten days of ATG or 3 months of high-dose nandrolone decanoate. No patient initially treated with androgens recovered, but 28% of ATG-treated cases achieved transfusion independence at 3 months. Group III consisted of patients with a variety of bone marrow failure syndromes. Patients with pancytopenia and cellular bone marrow showed response rates similar to those of patients with chronic or moderate aplastic anemia.