Diagnosis of immune pathophysiology in patients with bone marrow failure

Differential diagnosis of pancytopenia with bone marrow (BM) hypoplasia represented by aplastic anemia (AA) is often challenging for physicians, because no laboratory tests have been established, until recently, to distinguish immune-mediated BM failure, which includes acquired AA (aAA) and a subset of low-risk myelodysplastic syndrome (MDS), from non-immune BM failure, which is primarily caused by genetic abnormalities in hematopoietic stem cells (HSCs). HSCs of healthy individuals often undergo somatic mutations, and some acquire phenotypic changes that allow them to escape immune attack against themselves. Once an immune attack against HSCs occurs, HSCs that undergo somatic mutations survive the immune attack and continue to produce their progenies with the same genetic or phenotypic changes. The presence of mature blood cells derived from mutated HSCs in the peripheral blood serves as evidence of the immune-mediated destruction of HSCs. Glycosylphosphatidylinositol-anchored protein-deficient (GPI[-]) blood cells and HLA class I allele-lacking (HLA[-]) leukocytes are two major aberrant cell types that represent the immune mechanism underlying BM failure. This review focuses on the importance of identifying immune mechanisms using laboratory markers, including GPI(-) cells and HLA(-) leukocytes, in the management of BM failure.

Irisin protected hemopoietic stem cells and improved outcome of severe bone marrow failure

Acquired aplastic anemia (AA) is a bone marrow failure (BMF) disease, characterized by fatty bone marrow (BM) and BM hypocellularity resulted from auto-immune dysregulated T cells-mediated destruction of BM haemopoietic stem cells (HPSC). The objective of this study was to investigate potential therapeutic effect of irisin, a molecule involved in adipose tissue transition, on AA mouse model. Our results showed that the concentration of irisin in serum was lower in AA patients than in healthy controls, suggesting a role of irisin in the pathogenesis of AA. In the AA mice, irisin administration prolonged the survival rate, prevented or attenuated peripheral pancytopenia, and preserved HPSC in the BM. Moreover, irisin also markedly reduced BM adipogenesis. In vitro results showed that irisin increased both cell proliferation and colony numbers of HPSC. Furthermore, our results demonstrated that irisin upregulated the expression of mitochondrial ATPase Inhibitory Factor 1 (IF1) in HPSC, inhibited the activation of mitochondrial fission protein (DRP1) and enhanced aerobic glycolysis. Taken together, our findings indicate novel roles of irisin in the pathogenesis of AA, and in the protection of HPSC through stimulation of proliferation and regulation of mitochondria function, which provides a proof-of-concept for the application of irisin in AA therapy.

Gene therapy restores the transcriptional program of hematopoietic stem cells in Fanconi anemia

Clinical trials have shown that lentiviral-mediated gene therapy can ameliorate bone marrow failure (BMF) in nonconditioned Fanconi anemia (FA) patients resulting from the proliferative advantage of corrected FA hematopoietic stem and progenitor cells (HSPC). However, it is not yet known if gene therapy can revert affected molecular pathways in diseased HSPC. Single-cell RNA sequencing was performed in chimeric populations of corrected and uncorrected HSPC co-existing in the BM of gene therapy-treated FA patients. Our study demonstrates that gene therapy reverts the transcriptional signature of FA HSPC, which then resemble the transcriptional program of healthy donor HSPC. This includes a down-regulated expression of TGF-β and p21, typically up-regulated in FA HSPC, and upregulation of DNA damage response and telomere maintenance pathways. Our results show for the first time the potential of gene therapy to rescue defects in the HSPC transcriptional program from patients with inherited diseases; in this case, in FA characterized by BMF and cancer predisposition.

Haploinsufficiency of the essential gene Rps12 causes defects in erythropoiesis and hematopoietic stem cell maintenance

Ribosomal protein (Rp) gene haploinsufficiency can result in Diamond-Blackfan Anemia (DBA), characterized by defective erythropoiesis and skeletal defects. Some mouse Rp mutations recapitulate DBA phenotypes, although others lack erythropoietic or skeletal defects. We generated a conditional knockout mouse to partially delete Rps12. Homozygous Rps12 deletion resulted in embryonic lethality. Mice inheriting the Rps12KO/+ genotype had growth and morphological defects, pancytopenia, and impaired erythropoiesis. A striking reduction in hematopoietic stem cells (HSCs) and progenitors in the bone marrow (BM) was associated with decreased ability to repopulate the blood system after competitive and non-competitive BM transplantation. Rps12KO/+ lost HSC quiescence, experienced ERK and MTOR activation, and increased global translation in HSC and progenitors. Post-natal heterozygous deletion of Rps12 in hematopoietic cells using Tal1-Cre-ERT also resulted in pancytopenia with decreased HSC numbers. However, post-natal Cre-ERT induction led to reduced translation in HSCs and progenitors, suggesting that this is the most direct consequence of Rps12 haploinsufficiency in hematopoietic cells. Thus, RpS12 has a strong requirement in HSC function, in addition to erythropoiesis.

The chromatin remodeler CHD8 governs hematopoietic stem/progenitor survival by regulating ATM-mediated P53 protein stability

The Chd8 gene encodes a member of the chromodomain helicase DNA-binding (CHD) family of SNF2H-like adenosine triphosphate (ATP)-dependent chromatin remodeler, the mutations of which define a subtype of autism spectrum disorders. Increasing evidence from recent studies indicates that ATP-dependent chromatin-remodeling genes are involved in the control of crucial gene-expression programs in hematopoietic stem/progenitor cell (HSPC) regulation. In this study, we identified CHD8 as a specific and essential regulator of normal hematopoiesis. Loss of Chd8 leads to severe anemia, pancytopenia, bone marrow failure, and engraftment failure related to a drastic depletion of HSPCs. CHD8 forms a complex with ATM and its deficiency increases chromatin accessibility and drives genomic instability in HSPCs causing an activation of ATM kinase that further stabilizes P53 protein by phosphorylation and leads to increased HSPC apoptosis. Deletion of P53 rescues the apoptotic defects of HSPCs and restores overall hematopoiesis in Chd8-/- mice. Our findings demonstrate that chromatin organization by CHD8 is uniquely necessary for the maintenance of hematopoiesis by integrating the ATM-P53-mediated survival of HSPCs.

Immunodeficiency and bone marrow failure with mosaic and germline TLR8 gain of function

Inborn errors of immunity (IEI) are a genetically heterogeneous group of disorders with a broad clinical spectrum. Identification of molecular and functional bases of these disorders is important for diagnosis, treatment, and an understanding of the human immune response. We identified 6 unrelated males with neutropenia, infections, lymphoproliferation, humoral immune defects, and in some cases bone marrow failure associated with 3 different variants in the X-linked gene TLR8, encoding the endosomal Toll-like receptor 8 (TLR8). Interestingly, 5 patients had somatic variants in TLR8 with <30% mosaicism, suggesting a dominant mechanism responsible for the clinical phenotype. Mosaicism was also detected in skin-derived fibroblasts in 3 patients, demonstrating that mutations were not limited to the hematopoietic compartment. All patients had refractory chronic neutropenia, and 3 patients underwent allogeneic hematopoietic cell transplantation. All variants conferred gain of function to TLR8 protein, and immune phenotyping demonstrated a proinflammatory phenotype with activated T cells and elevated serum cytokines associated with impaired B-cell maturation. Differentiation of myeloid cells from patient-derived induced pluripotent stem cells demonstrated increased responsiveness to TLR8. Together, these findings demonstrate that gain-of-function variants in TLR8 lead to a novel childhood-onset IEI with lymphoproliferation, neutropenia, infectious susceptibility, B- and T-cell defects, and in some cases, bone marrow failure. Somatic mosaicism is a prominent molecular mechanism of this new disease.

Demonstration of IgG Subclass (IgG1 and IgG3) in Immuno-Related Hemocytopenia

BACKGROUND

Immuno-related hemocytopenia (IRH) is defined as idiopathic cytopenia of undetermined significance (ICUS) patients with autoantibodies. In our previous studies, we found that IgG1 levels were increased in IRH patients and might cause the destruction of hematopoietic cells.

METHODS

In this study, we analyzed IgG subclasses in 30 IRH patients (male:female = 13:17, median age 32 years, range 18 - 56), 15 IRH remission patients (IRH-R) (male:female = 6:9, median age 34, range 20 - 52) and 20 normal controls (male:female = 8:12, median age 27, range 24 - 36) by Cytometric Bead Array, Flow Cytometry and Immunohistochemical staining.

RESULTS

Levels of IgG1/IgG3 in the bone marrow supernatant of IRH patents, as well as the proportion of CD5+ B lymphocytes and Th2 cells (CD3+CD8-IL-4+) were higher than those of IRH-R patients and normal controls, and IgG1 levels had a positive correlation with the proportion of Th2 cells. In IRH patients, IgG1 and IgG3 were positive on nucleated erythrocytes and granulocytes, which were negative in IRH-R patients and healthy controls and had inverse correlations with hematopoietic function. Using immunohistochemical staining, IgG1 were also detected on bone marrow biopsies of IRH patients.

CONCLUSIONS

The results indicated that IgG1 and IgG3 autoantibodies in IRH patients might play a key role in the IRH pathogenesis and in the abnormal immune function of IRH patients.

Carboplatin-induced Fanconi-like syndrome in rats: amelioration by pentoxifylline

INTRODUCTION

Carboplatin is a congener of cisplatin used in the treatment of ovarian, head and neck and small-cell lung cancer. However, the clinical efficacy of carboplatin is marred by the development of ROS-dependent nephrotoxicity. The pathophysiological damage inflicted upon the kidney by carboplatin closely resembles to that of Fanconi syndrome.

AIMS AND OBJECTIVES

The present study aimed at inducing Fanconi-like syndrome in rats by administration of carboplatin. Objectives of the study involved evaluation of biochemical parameters coherent to Fanconi-like syndrome. Further, an attempt was made to evaluate the potential therapeutic effect of pentoxifylline in this condition.

RESULTS

The results of the study demonstrated that the urinary excretion profile of carboplatin treated rats closely resembled to that of patients suffering from Fanconi-like condition. Pentoxifylline was able to ameliorate this nephrotoxic condition as suggested by the change in levels of membrane bound ATPases, MDA and GSH. The urinary levels of tyrosine and cysteine correlate well with that of Fanconi-like condition in animals and humans.

CONCLUSION

In lieu of these observations, our study suggested that carboplatin-induced renovascular damage resembles to Fanconi-like condition which can be mitigated by pentoxifylline.

Preventive effects of Egyptian sweet marjoram (Origanum majorana L.) leaves on haematological changes and cardiotoxicity in isoproterenol-treated albino rats

We made an attempt to evaluate/compare the cardioprotective activity of two different doses (50 and 100 mg/kg body weight, given orally for 30 consecutive days) of Egyptian sweet marjoram leaf powder (MLP) and marjoram leaf aqueous extract (MLE) against isoproterenol (ISO)-induced myocardial infarcted rats (150 mg/kg body weight, twice at an interval of 24 h on days 29 and 30). The present study showed (probably for the first time) that both MLP and MLE (especially the high dose) significantly alleviated (P < 0.05-0.001) erythrocytosis, granulocytosis, thrombocytosis, shortened clotting time, the increase in relative heart weight, myocardial oxidative stress and the leakage of heart enzymes (creatine phosphokinase (CPK), CPK-MB isoenzyme, lactate dehydrogenase and aminotransferase) in ISO-treated rats through reactivating non-enzymic (reduced glutathione) and enzymic (catalase, glutathione peroxidase, glutathione S-transferase, superoxide dismutase) antioxidant defence system and inhibiting the production of nitric oxide and lipid peroxidation in heart tissues. The modulatory effects of marjoram leaves shown in the present study were dose-dependent in most cases and much higher in MLE (4.3-20.3 % for all parameters taken together). In addition, the doses used in the present study were considered safe. In conclusion, this study may have a significant impact on myocardial infarcted patients.

Increased frequency of bone marrow T follicular helper cells in patients with immune-related pancytopenia

Immune-related pancytopenia (IRP) is one kind of bone marrow failure diseases which is related to autoantibodies. Autoantibodies have been detected on the membrane of various bone marrow (BM) hemopoietic cells by BM mononuclear-cell-Coombs test or flow cytometric analysis. There are autoantibodies in the BM supernatant of IRP patients, which can target several antigens on hematopoietic cells membranes by western blot. T follicular helper (Tfh) cells are the true helper cells for Ab responses, which represent one of the most numerous and important subsets of effector T cells. Dysregulation of Tfh cell function or expression of Tfh cell-associated molecules could contribute to the pathogenesis of autoimmune diseases. Currently, there are no studies regarding the role of Tfh cells in IRP patients. The percentages of Tfh cells, Tfh-related molecules ICOS, CD40L, IL-21, and Bcl-6 in BM were investigated in 90 patients with IRP, and 25 healthy controls. We observed that there exist increased quantity and hyperfunction of Tfh cells in IRP, and the results were correlated with patient characteristics. It was indicated that dysregulated Tfh cells might be involved in the pathogenesis of IRP and that inhibition of Tfh cells effector molecules might provide opportunities for new therapeutic approaches to IRP and even other human autoimmune diseases.

[Changes of transcription factors Bcl-6, Foxp3 and RORγt in CD4(+) cells in bone marrow of immuno-related hematocytopenia]

OBJECTIVE

To evaluate the possible mechanism of transcription factors B cell lymphoma 6 (Bcl-6) , forkhead/winged helix transcription factor 3 (Foxp3) and retinoic acid related orphan receptor (RORγt) in CD4(+) T cells for immuno-related hematocytopenia (IRH).

METHODS

CD4(+) T cells were harvested from 40 IRH patients, 38 aplastic anemia subjects and 25 normal controls and separated by magnetic activated cell sorting (MACS). Then the expressions of transcription factors of Foxp3, RORγ and Bcl-6 in CD4(+) T cells were measured by real time fluorescent quantitative-polymerase chain reaction (QRT-PCR).

RESULTS

Auto-antibody was detected on CD34(+) cells (67.5% (27/40) ), CD15(+) cells (65.0% (26/40)), GlyA(+) cells (75.0% (30/40) ), auto-antibody involving three, two or one myeloid cell were detected in 27.5% (11/40), 52.5% (21/40), 20.0% (8/40) of IRH patients. Compensatory increase of Foxp3 mRNA was found in IRH (0.124 (0.073-0.198) vs 0.071 (0.046-0.118), P < 0.05). The expression of Bcl-6 was higher (2.243 (0.854-4.544) vs 1.211 (0.131-2.816), P < 0.05). Compared to aplastic anemia, the expression of RORγt was lower in IRH (0.133 (0.068-0.189) vs 0.290 (0.138-0.480), P < 0.01) and the ratio of Treg/Th17 shifted to Th17 in patients with aplastic anemia (Foxp3/RORγt ratio,0.500 (0.240-0.795) vs 0.975 (0.483-1.416), P < 0.01).

CONCLUSION

As one kind of bone marrow failures caused by autoantibody to bone marrow cells, IRH may occur due to a high expression of Bcl-6 in CD4(+) T cells, its immunopathogenesis is different from that of aplastic anemia.

Immune mechanism and clinical significance of macrophage to medullary hematopoietic injury of immune-related hematocytopenia patients

BACKGROUND

Immune-related hematocytopenia (IRH) is considered to be related with the production of autoantibody, as well as the activation of humoral immunity which is stimulated by B lymphocyte. This study aimed to observe the levels of various cytokines in the blood serum and the in situ active state of macrophage (Mφ) in the medullary hematopoietic microenvironment of IRH patients, and to probe into the immune mechanism and clinical significance of Mφ in hematopoietic cell injury.

METHODS

ELISA is used to detect the IL-4, IL-6, IL-12, IL-17, and IFN-γ levels in the peripheral blood serum of 376 patients in pre- and post-therapy. Cytochemistry and cell immunochemistry methods are used to observe the peroxidase (POX), nonspecific esterase (NSE), hemosiderin granules, and HLA-DR activity of Mφ in the bone marrow of patients. Immunofluorescence is used to observe the expression of hemocyte antihuman globulin IgG antibody, lymphocytes CD4 molecule, Mφ membrane FcγIIreceptor (FcγIIR), mannitose receptor (MR), IFN-γ, ICAM-1, IL-12, and IL-17A and the formation mechanism of antibody-dependent cell-mediated cytotoxicity (ADCC) hematopoietic cell islands (HI) in the medullary hematopoietic microenvironment of patients. Glucocorticoid is used for treatment on the basis of anti-infection therapy, and gamma globulin stoss therapy is used for the appearance of ADCC-type HI or serious Mφ bloodthirsty phenomenon; if necessary, association of Cyclosporine A (CsA) should be used and chalybeate should be supplemented.

RESULTS

In the patient group, the levels of IL-4, IL-6, IL-12, IL-17, and IFN-γ were increased. After treatment, the cytokine levels gradually became normal. The activated Mφ in the marrow highly expressed NSE and POX, and Mφ swallowed more hemosiderin particles, but the iron in the cytoplasm of immature erythrocytes decreased. The activated Mφ expressed HLA-DR, MR, ICAM-1, IFN-γ, and IL-12. For patients with humoral immunity activation and bacterial infection, Mφ weakly expressed IL-17A but highly expressed FcγIIR, and the phenomenon that ADCC-type HI broke pathological blood corpuscles often occurred; for the cellular immune activation along with virus infection, the white blood count (WBC) significantly reduced, Mφ weakly expressed FcγIIR, secretory highly expressed IL-17A, and the phenomena that Mφ adhered to, captured and swallowed blood cell often occurred. After four weeks of anti-infective and immunosuppressive therapy, nuclear apoptosis of Mφ occurred in the bone marrow of patients, HI and bloodthirsty phenomenon disappeared, and the peripheral blood picture started to improve.

CONCLUSIONS

Mφ is an important antigen presenting cell in the IRH marrow for hematopoiesis destruction and an immune effector cell of hematopoietic injury; infection can promote the activation of Mφ, upregulate the impression of immune molecule and receptors, form ADCC HI, aggravate hematopoietic injury, and accelerate the destruction on hematopoietic cell.

"Hyper-warburgism," a cause of asymptomatic hypoglycemia with lactic acidosis in a patient with non-Hodgkin's lymphoma

CONTEXT

In cancer cells, the Warburg effect is defined as the avid consumption of glucose through the glycolytic pathway with concomitant lactate production, even under aerobic conditions.

CASE

We report a 64-yr-old woman who was referred to our institution for pancytopenia and hypoglycemia. Physical examination demonstrated hepatosplenomegaly and petechiae. She had no clinical manifestation of neuroglycopenia, despite serum glucose of 26 mg/dl (1.4 mmol/liter) and serum lactate of 28.5 mmol/liter (normal range, 0.5-3.4 mmol/liter). Bone marrow biopsy demonstrated diffuse large B-cell lymphoma. Staging (18)F-fluorodeoxyglucose (FDG)-positron emission tomography/computed tomography showed increased FDG avidity in an enlarged spleen and absent FDG uptake in the brain. Despite dextrose infusions up to 30 g/h, there was no increase in serum glucose, but there was a paradoxical increase in serum lactate. Immunochemotherapy improved the hematological and metabolic abnormalities. Follow-up FDG-positron emission tomography/computed tomography showed a decrease in splenic avidity and an increase in brain FDG avidity. The patient refused further chemotherapy and died 1 wk after discharge.

METHODS

Literature review of cases of lymphoma with lactic acidosis, with and without hypoglycemia, demonstrated that these combinations occurred in multiple categories of B- and T-cell lymphoma. There was no difference in the mortality rate in those with (75%) or without (74%) concomitant hypoglycemia.

CONCLUSION

This case represents an exaggerated Warburg effect, or "hyper-warburgism," characterized by excessive lactate production and overwhelming glucose consumption. We speculate that the decreased brain FDG uptake, despite the lack of neuroglycopenic symptoms, supports the hypothesis that lactate served as a fuel for the brain, thus protecting against hypoglycemia.

[Preliminary study of autoantigens on the membrane of erythropoietic cells of the patients with BMMNC-Coomb's test(+) hemocytopenia]

OBJECTIVE

To observe the relationship between erythropoietin receptor (EPOR) and autoantibodies-IgG/IgM (auto-Ab) on the membrane of erythropoietic cells of the patients with bone marrow mononuclear cells (BMMNC)-Coomb's test(+) hemocytopenia (immunorelated pancytopenia (IRP)) and explore the probable autoantigens of auto-Ab in IRP.

METHODS

A total of 46 newly diagnosed IRP patients (15 with auto-Ab on erythropoietic cells and 31 without) and 18 healthy controls were enrolled. The EPOR expressions on their nuclear erythrocytes were tested with flow cytometry (FCM) to observe the relationship between EPOR and auto-Ab. EPOR mRNA was detected by reverse transcription (RT)-PCR. Stat5 and P-Stat5 proteins in nucleated erythrocytes were measured by Western blot. EPOR expressions on nucleated erythrocytes membrane were re-tested after stripping autoantibodies with glycine buffer.

RESULTS

(1) EPOR of auto-Ab(+) group (1.6% ± 0.9%)was significantly lower than that of auto-Ab(-) group (4.6% ± 4.1%, P < 0.01)and the latter was significantly higher than that of normal controls (2.3% ± 1.8%, P < 0.05). EPOR of IRP patients was inversely correlated with their auto-Ab (r = -0.543, P = 0.000). (2) EPOR mRNA of auto-Ab(+) group (0.68 ± 0.14)was significantly higher than that of auto-Ab(-) group (0.55 ± 0.12, P < 0.01) and normal controls (0.58 ± 0.12, P < 0.05). (3) Protein Stat5 of auto-Ab(+) group (1.45 ± 0.94) was significantly higher than that of normal controls (0.54 ± 0.36, P < 0.05). While P-Stat5 of auto-Ab(+) group (0.42 ± 0.18)was significantly lower than that of normal controls (0.85 ± 0.38, P < 0.05). (4) EPOR expression increased significantly after auto-Ab stripping.

CONCLUSIONS

The auto-Ab of some IRP patients blocks or competitively inhibits EPOR on the membrane of erythropoietic cells. And EPOR may be one of autoantigens in IRP.

[Clinical significance of telomerase activity detection of myeloid element in immune related hematocytopenia]

OBJECTIVE

To observe the telomerase activity (TA) in bone marrow mononuclear cell (BMMNC) at pre-therapy and post-therapy in patients with immune related hematocytopenia and immune related pancytopenia (IRH/IRP) so as to explore the relationship between TA and disease process.

METHODS

TA in BMMNC of 108 IRH/IRP patients was detected with telomeric repeat amplification protocol (TRAP)-PCR-ELISA. The expressions of anti-human immunoglobulin IgG, FcγII receptor (FcγIIR), mannose receptor (MR) and interleukin 17A (IL-17A) located on membrane surface were observed by immunofluorescence (IF). A total of 30 iron deficiency anemia patients were selected as case control.

RESULTS

The TA of 108 IRH/IRP patients were 0.251 ± 0.021. And it increased as compared with the control group of 0.062 ± 0.031 at pre-therapy (P < 0.01). The HLA-B27(+) patients among them was 0.270 ± 0.020 while HLA-B27(-) patients 0.181 ± 0.013 (P < 0.05). And HLA-B27(+)IgG elevated IRP was 0.341 ± 0.016 and HLA-B27(-)IgG elevated 0.183 ± 0.010, the difference of TA was significant between two groups (P < 0.01). IgG antibody positive immature hemocyte could be observed in marrow of IRH/IRP patients, and FcγIIR was expressed highly on those activated macrophage (Mφ) in bone marrow. Both IL-17A and MR were expressed on activated dendritic cells and Mφ in marrow of HLA-B27(+) patients. After the therapy of glucocorticoids associated with cyclosporine A and other drugs, the patient's hemogram recovered and the telomerase in BMMNC were re-devitalized.

CONCLUSIONS

The TA of the BMMNC in marrow of IRH/IRP patients is increased, and it shows a close relation between apoptotic degree of hematopoietic cell and the activation of immunocytes. In IRH/IRP, synchronism and equilibrium exist between BMMNC apoptosis and TA.

Research progress on the red cell diseases in China

In recent years, there have been lots of progresses in the studies on red cell diseases in China, especially bone marrow failure diseases including immuno-related pancytopenia, aplastic anemia, myelodysplastic syndrome, and paroxymal nocturnal hemoglobinuria. Numerous laboratory experiments as well as clinical researches have been carried out by Chinese hematologists, which brought about much clearer pathogenesis, more rational diagnosis methods and more effective therapies for red cell diseases.

Transcobalamin II deficiency at birth

Transcobalamin II deficiency (# MIM 275350) is a rare, recessively inherited disorder of cobalamin transport that leads to intracellular cobalamin depletion with secondary impairment of methionine synthetase and methyl-malonyl CoA mutase activities. Affected individuals may suffer from long-term neurological sequelae if therapy with intramuscular hydroxocobalamin is not initiated promptly. We report two sisters with complete absence of transcobalamin due to homozygosity for a novel mutation (c.insC110) in the TCN2 gene that leads to a premature stop codon and non-functional protein. The older sister, now 4.5 years old, presented at 6 weeks of age with pancytopenia, protein losing enteropathy and a rapidly declining clinical course. Prompt therapy with 1mg hydroxocobalamin/day led to full recovery within days. Her now 1.5 year old sister was diagnosed shortly after birth and was started on hydroxocobalamin prior to onset of clinical symptoms. Interestingly, urinary methylmalonic acid excretion was increased significantly during the first days of life suggesting that functional cobalamin deficiency is present also during fetal life, although not giving rise to clinical symptoms until well after birth.

[Variation in complement level and its significance in cytopenia patients with positive BMMNC-Coombs]

OBJECTIVE

To investigate the variation of bone marrow complement level in cytopenia patients with positive BMMNC-Coombs test (CBCPC), and probe the role of complement in destroying hematopoietic cells of CBCPC patients.

METHODS

One hundred and twenty-four patients with CBCPC and twenty-three healthy donors as controls were enrolled in this study. The levels of CH50, C3, C4, C5b-9 were tested with ELISA. The auto-antibodies on bone marrow hematopoietic cells (BMHC) were examined with flow cytometry.

RESULTS

The level of C5b-9 in bone marrow (BM) of untreated CBCPC patients [(119.8+/-54.0) microg/L] was significantly higher than that of recovered patients [(100.7+/-33.4) microg/L] or normal controls [(93.9+/-28.8) microg/L] (P<0.05). The levels of CH50 in BM of untreated or recovered CBCPC patients [(33.3+/-11.5) kU/L, (30.8+/-10.3) kU/L] were significantly higher than that of normal controls [(24.1+/-6.4) kU/L] (P<0.05). The level of C3 in BM of untreated or recovered CBCPC patients [(4.9+/-2.2) mg/L], (5.0+/-3.5) mg/L] was significantly lower than that of normal controls [(7.0+/-5.6) mg/L] (P<0.05). The level of complement in peripheral blood was consistent with that in BM. CH50 in BM of CBCPC patients was negatively correlated with their C3 (r=-0.303, P=.0007) and positively correlated with their C5b-9 (r=0.241, P=0.003) levels. The level of C5b-9 in BM of CBCPC patients was higher in the BMHC-IgM positive group [(117.6+/-55.7) microg/L] than in the BMHC- IgM negative group [(99.2+/-26.2) microg/L] (P<0.05). The positive rate of CD34(+)-IgG or CD34(+)-IgM of CBCPC patients was positively correlated with their C5b-9 level (r=0.593, P=0.000, r=0.326, P=0.049). The reticulocyte percentage (r=0.421, P=0.000) and serum indirect bilirubin level (r=0.230, P=0.032) of CBCPC patients were positively correlated with their CH50 level.

CONCLUSIONS

The hematocytopenia of CBCPC patients might be related to the hematopoietic cells destruction caused by auto-antibody activated complements.

CCR2 is required for CD8-induced graft-versus-host disease

Graft-versus-host disease (GVHD) is a major complication of allogeneic hematopoietic stem cell transplantation (HSCT). Migration of donor-derived T cells into GVHD target organs plays a critical role in the development of GVHD and chemokines and their receptors are important molecules involved in this process. Here, we demonstrate in murine bone marrow transplantation models that the expression of the inflammatory CC chemokine receptor 2 (CCR2) on donor-derived CD8+ T cells is relevant for the control of CD8+ T-cell migration and development of GVHD. Recipients of CCR2-deficient (CCR2-/-) CD8+ T cells developed less damage of gut and liver than recipients of wild-type CD8+ T cells, which correlated with a reduction in overall GVHD morbidity and mortality. Assessment of donor CD8+ T-cell target organ infiltration revealed that CCR2-/- CD8+ T cells have an intrinsic migratory defect to the gut and liver. Other causes for the reduction in GVHD could be excluded, as alloreactive proliferation, activation, IFN-gamma production and cytotoxicity of CCR2-/- CD8+ T cells were intact. Interestingly, the graft-versus-tumor effect mediated by CCR2-/- CD8+ T cells was preserved, which suggests that interference with T-cell migration by blockade of CCR2 signaling can separate GVHD from GVT activity.

Drug-induced toxic epidermal necrolysis and pancytopenia: a puzzling association

The molecular mechanisms involved in the pathogenesis of toxic epidermal necrolysis (TEN) remain not fully understood. We report a unique case of antibiotic-induced TEN developed in a patient who also suffered from prolonged severe methotrexate-induced pancytopenia. The objective of the study was to explore the nature of the cutaneous inflammatory infiltrate and the density in dermal dendrocytes (DD). Immunohistochemistry was used to identify activated T lymphocytes (CD45R0), monocyte-macrophages (Mac 387, CD68), DD (Factor XIIIa), and Langerhans cells (CD1a). The proliferation marker (Ki67) and the antibody to Fas receptor (CD95R) were also used to assess the distribution of the germinative pool of keratinocytes and the FAS-related apoptotic process, respectively. Numerous Factor XIIIa+ DD were present in the papillary dermis with only sparce perivascular CD45RO+ T lymphocytes and scattered CD68+ or Mac 387+ macrophages. Double immunostainings revealed that a minority of Factor XIIIa+ DD co-expressed the CD68 glycoprotein (a marker of phagocytic activity). No cells co-expressed factor XIIIa and Mac 387 immunoreactivities. CD45RO+ T lymphocytes, CD68+ and Mac 387+ macrophages were absent in the epidermis. The expression of CD95R was present although restricted to the basal keratinocytes, while the L1-protein (Mac 387+) was diffusely present in the epidermis. Langerhans cells (CD1a+) were sparce, but normal in distribution. The presence of a great number of Factor XIIIa+ DD without any possible recent recruitment from bone marrow suggests that these cells differentiated from resident cells of the skin. Indeed, there was no co-expression of Factor XIIIa and L1-protein, thus showing the absence of recruitment from monocytes. The simultaneous over-expression of Factor XIIIa and CD68 in some DD indicates some phagocytic activity. In view of the absence of inflammatory cells in the epidermis, keratinocytes appeared responsible for their own destruction through CD95-mediated and/or calcium-dependent apoptotic pathways. This finding entails that TEN treatments should target the keratinocyte metabolism rather than the circulating inflammatory cells which presumably play a limited role, if any, in the epidermal destructive process.

HIF-2α regulates murine hematopoietic development in an erythropoietin-dependent manner

Erythropoiesis in the adult mammal depends critically on erythropoietin, an inducible cytokine with pluripotent effects. Erythropoietin gene expression increases under conditions associated with lowered oxygen content such as anemia and hypoxia. HIF-1α, the founding member of the hypoxia-inducible factor (HIF) alpha class, was identified by its ability to bind and activate the hypoxia-responsive enhancer in the erythropoietin regulatory region in vitro. The existence of multiple HIF alpha members raises the question of which HIF alpha member or members regulates erythropoietin expression in vivo. We previously reported that mice lacking wild-type HIF-2α, encoded by the EPAS1 gene, exhibit pancytopenia. In this study, we have characterized the etiology of this hematopoietic phenotype. Molecular studies of EPAS1-null kidneys reveal dramatically decreased erythropoietin gene expression. EPAS1-null as well as heterozygous mice have impaired renal erythropoietin induction in response to hypoxia. Treatment of EPAS1-null mice with exogenous erythropoietin reverses the hematopoietic and other defects. We propose that HIF-2α is an essential regulator of murine erythropoietin production. Impairments in HIF signaling, involving either HIF-1α or HIF-2α, may play a prominent role in conditions involving altered hematopoietic or erythropoietin homeostasis.

Bone marrow immunoscintigraphy in haematological patients with pancytopenia: preliminary results

The aim of this study was to assess the clinical value of bone marrow immunoscintigraphy using the (99m)Tc labelled anti-NCA-95 antigranulocyte antibodies (AGAb) and of AGAb bone marrow uptake ratio (UR) in the initial diagnostic work-up of diseases with depression of the bone marrow. Twenty-four whole-body bone marrow scans were performed in 23 patients (11 women, 12 men; median age 46 years, range 17-74 years) 5 h after i.v. injection of 370 MBq of AGAb. The UR was calculated from the posterior view drawing an irregular region of interest around the sacroiliac and a background areas. The mean UR in pancytopenic patients was 2.3+/-1.5 (range 0.3-5.8), thus being significantly lower (P=0.45 x 10(-6)) than the mean UR in a control group of 50 patients (mean UR 7.3+/-2.3; range 4.4-12.6) obtained previously. Considering patient age, there was no overlap between UR of pancytopenic patients and the respective normal ranges. The bone marrow appearance on scans seemed to be characteristic for the different haematological diseases investigated. In six patients with myelofibrosis, bone marrow scans demonstrated diffusely decreased bone marrow activity and prominent splenic uptake, possibly related to extramedullary haematopoiesis. In aplastic anaemia, highly reduced and patchy marrow uptake was observed in four patients (five scans), in one of them persisting even after blood cell counts had recovered to the near-normal range. In another two patients with aplastic anaemia, diffusely decreased bone marrow uptake was obtained. In patients with myeloid leukaemia, bone marrow patterns were almost normal probably because the target antigen is often expressed on neoplastic myeloid cells, too. Bone marrow extension was a common finding in these patients. There is an obvious differentiation between haematological patients with pancytopenia and normal subjects by means of AGAb bone marrow uptake ratio. The distinct patterns of AGAb distribution may be indicative for particular haematological diseases.

[Quantity and apoptosis-related protein level of B lymphocyte in patients with immunorelated pancytopenia]

OBJECTIVE

To examine the quantity and apoptosis-related protein level of B lymphocyte in the patients with immunorelated pancytopenia (IRP) and explore the role of B lymphocyte in the pathogenetic mechanism of IRP.

METHODS

Quantities of all B lymphocytes and CD(5)(+) B lymphocytes and the expressions of Fas and bcl-2 on B lymphocytes in 25 patients with untreated IRP, 15 IRP patients in complete remission (CR) and 10 normal controls were assayed by FACS.

RESULTS

The percentages of B lymphocyte and CD(5)(+) B lymphocytes were significantly higher in untreated IRP patients than in CR IRP patients and normal controls (P < 0.05); there was no significant difference between the latter two groups (P > 0.05). There was no significant difference of Fas expression in B lymphocytes among the three groups (P > 0.05). The expression of bcl-2 on B lymphocytes was significantly higher in untreated patients than in CR patients or normal controls (P < 0.05), and so did in CR patients than in normal controls (P < 0.01). The apoptosis-related index was significantly lower in untreated patients than in CR patients or normal controls (P < 0.01), and was lower in CR patients than in normal controls (P < 0.05). The percentage of B lymphocyte was positively correlated with the duration from the beginning of treatment to response.

CONCLUSION

The production of auto-antibodies in IRP patients probably has some relationships with the abnormal quantities of B lymphocyte and its subsets, and with the inhibition of B lymphocyte apoptosis.

Drugs elevating extracellular adenosine promote regeneration of haematopoietic progenitor cells in severely myelosuppressed mice: their comparison and joint effects with the granulocyte colony-stimulating factor

We tested capabilities of drugs elevating extracellular adenosine and of granulocyte colony-stimulating factor (G-CSF) given alone or in combination to modulate regeneration from severe myelosuppression resulting from combined exposure of mice to ionizing radiation and carboplatin. Elevation of extracellular adenosine was induced by joint administration of dipyridamole (DP), a drug inhibiting the cellular uptake of adenosine, and adenosine monophosphate (AMP), serving as an adenosine prodrug. DP+AMP, G-CSF or all these drugs in combination were administered in a 4-d treatment regimen starting on day 3 after induction of myelosuppression. Comparable enhancements of haematopoietic regeneration due to elevation of extracellular adenosine or to action of G-CSF were demonstrated as shown by elevated numbers of haematopoietic progenitor cells for granulocytes/macrophages (GM-CFC) and erythrocytes (BFU-E) in the bone marrow and spleen in early time intervals after termination of the drug treatment, i.e. on days 7 and 10 after induction of myelosuppression. Coadministration of all the drugs further potentiated the restoration of progenitor cell pools in the haematopoietic organs. The effects of the drug treatments on progenitor cells were reflected in the peripheral blood in later time intervals of days 15 and 20 after induction of myelosuppression, especially as significantly elevated numbers of granulocytes and less pronounced elevation of lymphocytes and erythrocytes. The results substantiate the potential of drugs elevating extracellular adenosine for clinical utilization in myelosuppressive states, e.g. those accompanying oncological radio- and chemotherapy.

Alveolar macrophage activity and the pulmonary complications of haematopoietic stem cell transplantation

BACKGROUND

The success of haematopoietic (bone marrow or peripheral blood) stem cell transplantation (SCT) is compromised by pulmonary complications. We hypothesised that a proinflammatory alveolar microenvironment, reflected in alveolar macrophage (AM) cytokine production, would predispose to such complications.

METHODS

AM were isolated from adult SCT recipients by bronchoalveolar lavage before SCT (n=32) and during post-transplant pancytopenia (n=23). Concentrations of tumour necrosis factor (TNF)alpha, granulocyte-macrophage colony stimulating factor (GM-CSF), interleukin (IL)-1 beta, IL-6, and IL-8 in 24 hour AM culture medium were measured by enzyme linked immunosorbent assay and compared with both the occurrence of post-SCT lung disease and with subjects' previous respiratory histories.

RESULTS

Eleven subjects developed lung disease within 6 months of SCT. These subjects had higher median pre-transplant AM TNFalpha (8 (IQR 1-8) v 2 (1-5) ng/10(6)AM, p=0.01, median difference (D) = 3, 95% CI 0.1 to 7), GM-CSF (5 (0.7-8) v 0.2 (0.1-0.8), p=0.006, D = 4, 95% CI 0.5 to 7), and IL-6 (0.5 (0.1-1) v 0.1 (0.02-0.3), p=0.049, D = 0.3, 95% CI 0.0002 to 1) production than remaining subjects; IL-1 beta and IL-8 did not differ. During pancytopenia high AM GM-CSF production again predicted later lung disease (1 (0.7-9) v 0.1 (0.06-0.3), p=0.01, D = 1, 95% CI 0.1 to 6). A history of recent chest disease was associated with high AM TNFalpha and GM-CSF production and with post-SCT lung disease. Pre-SCT lung function was unrelated to post-SCT lung disease.

CONCLUSIONS

Recent respiratory disease and persistent proinflammatory AM behaviour detectable before transplantation are associated with lung disease following SCT. These associations may prove useful in pre-transplant risk assessment.

In vivo biological effects of various forms of thrombopoietin in a murine model of transient pancytopenia

Thrombopoietin (TPO) is the natural regulator of platelet production in the bone marrow of mammals. This cytokine also seems to play an important role in the development of the erythroid lineage when recovering from anemic conditions. Here we study the effects of various TPO molecules on the recovery of hematopoietic lineages in a mouse model of pancytopenia. Based on previous animal experimentation and clinical experience with other hematopoietic cytokines, we found that daily dosing with TPO augmented the recovery of both the megakaryocyte and erythroid lineages in a mouse model of pancytopenia. However, further experiments showed that no benefit was gained by using more than a single dose of recombinant murine (rm)TPO(335) given 24 h after the initiation of the myelosuppressive treatment. This response to a single dose of rmTPO(335) is dose-dependent. However, the response was attenuated when a truncated, short half-life TPO molecule (rmTPO[153]) was used. Increasing the half-life of the molecule with 10 kDa polyethylene glycol (PEG) does not improve the response. Only when larger PEG molecules (20 kDa or 40 kDa) are linked to the rmTPO(153) is the response to single doses restored to the level of the full-length molecule. These data suggest that, unlike our experience with other cytokines, the commitment of progenitors to a megakaryocytic cell line is accomplished by a single short exposure to TPO.

Pancytopenia associated with low dose methotrexate therapy. A regional survey

OBJECTIVE

To determine which risk factors are associated with serious pancytopenia associated with low dose methotrexate (MTX) therapy.

METHODS

All Ottawa area rheumatologists, hematologists and dermatologists were surveyed to obtain cases of pancytopenia associated with low dose MTX therapy between 1981 and 1991. Pancytopenia was defined as white blood cells < 3.5 x 10(9)/l and platelets < 140 x 10(9)/l and hemoglobin < 100 g/l. A case control method was used to evaluate risk factors.

RESULTS

Fifteen cases of pancytopenia were identified from returned questionnaires (93% response rate) and from reviewing the medical records of 2 major teaching hospitals. All patients were hospitalized, had MTX therapy discontinued and were treated: 12 patients received transfusions, 8 leucovorin therapy, and 4 folic acid. Two patients died, only 1 directly due to MTX therapy. Identified risk factors were (1) elevated BUN or creatinine levels, (2) increasing mean corpuscular volume values, (3) increased age and (4) concomitant trimethoprim-sulfamethoxazole therapy.

CONCLUSIONS

Pancytopenia associated with low dose MTX therapy is a life threatening adverse effect often associated with known risk factors. A change in monitoring guidelines and patient education are suggested as means of risk reduction.