Clinical significance of a small population of paroxysmal nocturnal hemoglobinuria-type cells in the management of bone marrow failure

A longitudinal analysis of paroxysmal nocturnal haemoglobinuria-type cells in patients with bone marrow failure: Results of a prospective multi-centre study in Japan

To determine the prevalence and clinical relevance of glycosylphosphatidylinositol-anchored protein-deficient (GPI[-]) cell populations (paroxysmal nocturnal haemoglobinuria [PNH]-type cells) in patients with acquired aplastic anaemia (AA) or myelodysplastic syndrome (MDS), we prospectively studied peripheral blood samples of 2402 patients (1075 with AA, 900 with MDS, 144 with PNH, and 283 with other anaemia) using a high-sensitivity flow cytometry assay in a nationwide multi-centre observational study. PNH-type cells were detected in 52.6% of AA and 13.7% of MDS patients. None of the 35 patients with refractory anaemia (RA) with ringed sideroblasts or the 86 patients with RA with excess of blasts carried PNH-type cells. Among the 317 patients possessing PNH-type granulocytes, the percentage of PNH-type granulocytes increased by ≥10% in 47 patients (14.8%), remained unchanged in 240 patients (75.7%), and decreased by ≥10% in 30 patients (9.5%) during 3 years of follow-up. PNH-type granulocyte expansion occurred more frequently (27.1%) in the 144 patients who originally carried PNH-type granulocytes ≥1% than in the 173 patients with PNH-type granulocytes <1% (4.6%). This study confirmed that PNH-type cells are undetectable in authentic clonal MDS patients, and the presence of ≥1% PNH-type granulocytes predicts a higher likelihood of PNH-type cell expansion than with <1% PNH-type granulocytes.

Dysplasia and PNH-type cells in bone marrow aspirates of myelodysplastic syndromes

BACKGROUND

Flow cytometry is increasingly applied in cytopenic patients suspected for myelodysplastic syndromes (MDS). Analysis includes evaluation of antigen expression patterns in granulocytes of which, for example, partial lack of CD16 may indicate dysplasia, but presence of paroxysmal nocturnal hemoglobinuria (PNH)-type cells should be considered. However, diagnostic bone marrow (BM) samples hamper PNH analysis because immature stages in the granulo-/monocytic compartment lack expression of certain glycophosphatidyl-inositol-anchored proteins. In this prospective study, we evaluated the presence of PNH-type cells in BM next to aberrancies from routine MDS immunophenotyping.

METHODS

We combined antibodies defining maturation trajectories with FLAER. Validation of the designed method against routine PNH analysis and parallel analysis of BM and blood samples revealed similar results (granulocytes: Wilcoxon p = 0.25 and p = 0.82, respectively). We analyzed BM samples from 134 MDS, 17 chronic myelomonocytic leukemia, 15 aplastic anemia (AA), 1 PNH, 51 non-clonal cytopenic controls, and 12 normal controls.

RESULTS

Most AA/PNH-BM samples showed clear PNH clones: median 1.1% (0%-35%); CD16 loss on mature neutrophils paralleled PNH-clone sizes. In MDS-BM, only 3.7% of cases showed ≥0.1% PNH-type cells, whereas partial CD16 loss was more frequent and abundant.

CONCLUSIONS

Our findings confirm that dysplastic features in MDS-BM may point to presence of PNH-type cells, though only few cases displayed FLAER-negative cells. We showed that identification of these cells in the granulocyte compartment of BM specimen is feasible, but-according to international guidelines-results need to be confirmed in peripheral blood.

The predictive value of PNH clones, 6p CN-LOH, and clonal TCR gene rearrangement for aplastic anemia diagnosis

Acquired aplastic anemia (AA) is a life-threatening bone marrow aplasia caused by the autoimmune destruction of hematopoietic stem and progenitor cells. There are no existing diagnostic tests that definitively establish AA, and diagnosis is currently made via systematic exclusion of various alternative etiologies, including inherited bone marrow failure syndromes (IBMFSs). The exclusion of IBMFSs, which requires syndrome-specific functional and genetic testing, can substantially delay treatment. AA and IBMFSs can have mimicking clinical presentations, and their distinction has significant implications for treatment and family planning, making accurate and prompt diagnosis imperative to optimal patient outcomes. We hypothesized that AA could be distinguished from IBMFSs using 3 laboratory findings specific to the autoimmune pathogenesis of AA: paroxysmal nocturnal hemoglobinuria (PNH) clones, copy-number-neutral loss of heterozygosity in chromosome arm 6p (6p CN-LOH), and clonal T-cell receptor (TCR) γ gene (TRG) rearrangement. To test our hypothesis, we determined the prevalence of PNH, acquired 6p CN-LOH, and clonal TRG rearrangement in 454 consecutive pediatric and adult patients diagnosed with AA, IBMFSs, and other hematologic diseases. Our results indicated that PNH and acquired 6p CN-LOH clones encompassing HLA genes have ∽100% positive predictive value for AA, and they can facilitate diagnosis in approximately one-half of AA patients. In contrast, clonal TRG rearrangement is not specific for AA. Our analysis demonstrates that PNH and 6p CN-LOH clones effectively distinguish AA from IBMFSs, and both measures should be incorporated early in the diagnostic evaluation of suspected AA using the included Bayesian nomogram to inform clinical application.

Approach to the diagnosis of aplastic anemia

Establishing a diagnosis of aplastic anemia (AA) can be challenging, but it is absolutely critical to appropriate management, especially differentiating between acquired and inherited forms of the disease. The hematology field requires updated diagnostic guidelines to ensure that appropriate clinical pathways are pursued for patients and their safety. There are increasing clinical options for patients with immunosuppressive therapy and transplant once the diagnosis is made. In a case-based format, this review emphasizes the newer data on molecular (somatic and germline) findings in AA and how they are (or are not) helpful during diagnosis. There are key details on somatic mutation profiles and stated evidence where available for prognostic and treatment indications. Germline details of newer syndromes are also outlined, which make this review modern and reflect areas of uncertainty for clinicians.

ICCS/ESCCA consensus guidelines to detect GPI-deficient cells in paroxysmal nocturnal hemoglobinuria (PNH) and related disorders part 1 - clinical utility

Paroxysmal nocturnal hemoglobinuria (PNH) arises as a consequence of the non-malignant clonal expansion of one or more hematopoietic stem cells with an acquired somatic mutation of the PIGA gene (Brodsky RA. Blood 113 (2009) 6522-6527). Progeny of affected stem cells are deficient in glycosyl phosphatidylinositol-anchored proteins (GPI-APs). This deficiency is readily detected by flow cytometry. Though this seems straightforward, the clinical utility of this testing requires that the ordering clinician understand not only the characteristics of the test, but also the biology of the underlying disease, and the clinical and laboratory manifestations in the individual patient. When interpreted correctly, the results from PNH flow cytometry testing, including presence and size of the clonal populations and the cell types involved, can allow the clinician to classify the disease appropriately; evaluate the risk of disease progression; and subsequently monitor response to therapy. In these guidelines, we discuss the evaluation of a patient with suspected PNH or other bone marrow failure disorders, with specific emphasis on the contribution of this testing to the diagnosis, classification, and monitoring of patients. For convenience we will commonly refer to these flow cytometry studies as "PNH testing" recognizing that an abnormal result is not diagnostic of PNH; rather both laboratory and clinical features are used to establish this diagnosis. © 2017 International Clinical Cytometry Society.

Eculizumab Bridging before Bone Marrow Transplant for Marrow Failure Disorders Is Safe and Does Not Limit Engraftment

Paroxysmal nocturnal hemoglobinuria (PNH) often develops secondary to other bone marrow failure (BMF) disorders, especially aplastic anemia (AA). Patients with the AA/PNH syndrome may require treatment with both eculizumab to reduce intravascular hemolysis and the risk of thrombosis and allogeneic stem cell transplant for the severe BMF. There has been concern that eculizumab could adversely affect the outcomes for transplant in these patients. This is a retrospective, single-center study of severe AA (SAA)/PNH patients treated with eculizumab immediately before the start of conditioning for transplant. Metrics of engraftment and infectious outcomes are described. Eight patients with SAA/PNH and PNH-related symptoms were treated with eculizumab and then proceeded to transplant. All were successfully transplanted without adverse events related to C5 blockage before conditioning. All were also cured of their both PNH and SAA. Eculizumab is safe and efficacious in patients with PNH clones who require transplant. This is sometimes required to "bridge" patients before bone marrow transplantation and does not appear to adversely impact outcomes even when using HLA matched unrelated or haploidentical donors.

Diagnostic screening of paroxysmal nocturnal hemoglobinuria: Prospective multicentric evaluation of the current medical indications

BACKGROUND

Although consensus guidelines have been proposed in 2010 for the diagnostic screening of paroxysmal nocturnal hemoglobinuria (PNH) by flow cytometry (FCM), so far no study has investigated the efficiency of such medical indications in multicentric vs. reference laboratory settings.

METHODS

Here we evaluate the efficiency of consensus medical indications for PNH testing in 3,938 peripheral blood samples submitted to FCM testing in 24 laboratories in Spain and one reference center in Brazil.

RESULTS

Overall, diagnostic screening based on consensus medical indications was highly efficient (14% of PNH⁺ samples) both in the multicenter setting in Spain (10%) and the reference laboratory in Brazil (16%). The highest frequency of PNH⁺ cases was observed among patients screened because of bone marrow (BM) failure syndrome (33%), particularly among those with aplastic anemia (AA; 45%) and to a less extent also a myelodysplastic syndrome (MDS; 10%). Among the other individuals studied, the most efficient medical indications for PNH screening included: hemolytic anemia (19%), hemoglobinuria (48%) and unexplained cytopenias (9%). In contrast, only a minor fraction of the patients who had been submitted for PNH testing because of unexplained thrombosis in the absence of cytopenia, were positive (0.4%).

CONCLUSIONS

In summary, our results demonstrate that the current medical indications for PNH screening by FCM are highly efficient, although improved screening algorithms are needed for patients presenting with thrombosis and normal blood cell counts. © 2016 International Clinical Cytometry Society.

[Clinical characteristics and evolution of paroxysmal nocturnal hemoglobinuria clones in patients with acquired aplastic anemia]

目的

分析伴阵发性睡眠性血红蛋白尿症(PNH)克隆的再生障碍性贫血(AA)患者临床特点，以及PNH克隆大小演变对疗效和生存的影响。

方法

回顾2011年1月至2014年9月间收治的316例诊断明确的AA患者临床资料，分析其临床特点及PNH克隆大小演变对疗效和生存的影响。

结果

①316例AA患者中90例(28.5%) PNH克隆阳性，有随访资料的83例患者完全缓解(CR) 36例(43.4%)，部分缓解(PR)28例(33.7%)，有效率为77.1%。3年及5年总生存(OS)率分别为79.4％与76.1%。②24例免疫抑制治疗(IST)后PNH克隆转为阳性，PNH克隆持续阳性者22例，PNH克隆消失者10例，三组间有效率、OS率、网织红细胞(Ret)绝对值、总胆红素、间接胆红素、LDH差异均无统计学意义(P值均>0.05)；共10例患者进展为AA-PNH综合征，中位进展时间15.6个月，有效率及OS率与其他46例患者比较差异无统计学意义(P值分别为0.896、0.688)。③单因素分析显示年龄≥55岁、合并感染、极重型AA(VSAA)、中性粒细胞绝对计数(ANC)<0.5×10⁹/L、Ret绝对值<0.012×10¹²/L为影响患者OS的因素(P值分别为0.026、0.000、0.001、0.000及0.010)；而多因素Cox回归模型分析显示年龄≥ 55岁[RR=2.871(95%CI 0.998~8.263)，P=0.050]、合并感染[RR=2.165 (95%CI 0.064~0.712)，P=0.012]及ANC <0.5×10⁹/L [RR=4.902(95%CI 0.041~1.004)，P=0.050]为影响患者OS的独立预后因素。单因素及多因素分析均未发现PNH克隆大小与疗效及长期生存的相关性。

结论

PNH克隆的大小及其演变对患者疗效及长期生存无明显影响。

Biomarkers for predicting clinical response to immunosuppressive therapy in aplastic anemia

The decision to select hematopoietic stem cell transplantation (HSCT) or immunosuppressive therapy (IST) as initial therapy in acquired aplastic anemia (AA) is currently based on patient age and the availability of a human leukocyte antigen (HLA)-matched donor. Although IST is a promising treatment option, the ability to predict its long-term outcomes remains poor due to refractoriness, relapses, and the risk of clonal evolution. Several predictive biomarkers for response to IST have been posited, including age, gender, pre-treatment blood cell counts, cytokines, gene mutations, paroxysmal nocturnal hemoglobinuria (PNH), and telomere length (TL). While previous studies have provided substantial biological insights into the utility of IST, the prognostic power of the reported biomarkers is currently insufficient to contribute to clinical decision making. Recently, a large retrospective analysis proposed the combination of minor PNH clones and TL as an efficient predictor of IST response. Identification of a reliable predictor would provide a useful tool for determining the most appropriate treatment choice for AA patients, including up-front HSCT from HLA-matched unrelated donor. The present review summarizes studies evaluating the utility of biomarkers in predicting the clinical response to IST of patients with AA, and provides a baseline for prospective studies aimed at validating previously reported biomarkers.

Paroxysmal nocturnal hemoglobinuria: a complement-mediated hemolytic anemia

Paroxysmal nocturnal hemoglobinuria is manifests with a chronic hemolytic anemia from uncontrolled complement activation, a propensity for thrombosis and marrow failure. The hemolysis is largely mediated by the alternative pathway of complement. Clinical manifestations result from the lack of specific cell surface proteins, CD55 and CD59, on PNH cells. Complement inhibition by eculizumab leads to dramatic clinical improvement. While this therapeutic approach is effective, there is residual complement activity resulting from specific clinical scenarios as well as from upstream complement components that can account for suboptimal responses in some patients. Complement inhibition strategies are an area of active research.

The challenging world of cytopenias: distinguishing myelodysplastic syndromes from other disorders of marrow failure

Over the past decade, our understanding of bone marrow failure has advanced considerably. Marrow failure encompasses multiple overlapping diseases, and there is increasing availability of diagnostic tools to distinguish among the subtypes. Identification of genetic alterations that underlie marrow failure has also greatly expanded, especially for myelodysplastic syndromes. Molecular markers are increasingly used to guide the management of myelodysplasia and may distinguish this diagnosis from other marrow failure disorders. This review summarizes the current state of distinguishing among causes of marrow failure and discusses the potential uses of multiple diagnostic and prognostic indicators in the management of myelodysplastic syndromes and other bone marrow failure disorders.

An inter-laboratory comparison of PNH clone detection by high-sensitivity flow cytometry in a Russian cohort

OBJECTIVES

Paroxysmal nocturnal hemoglobinuria (PNH) is an acquired clonal stem cell disorder characterized by partial or absolute deficiency of glycophosphatidyl-inositol (GPI) anchor-linked surface proteins on blood cells. A lack of precise diagnostic standards for flow cytometry has hampered useful comparisons of data between laboratories. We report data from the first study evaluating the reproducibility of high-sensitivity flow cytometry for PNH in Russia.

METHODS

PNH clone sizes were determined at diagnosis in PNH patients at a central laboratory and compared with follow-up measurements in six laboratories across the country. Analyses in each laboratory were performed according to recommendations from the International Clinical Cytometry Society (ICCS) and the more recent 'practical guidelines'. Follow-up measurements were compared with each other and with the values determined at diagnosis.

RESULTS

PNH clone size measurements were determined in seven diagnosed PNH patients (five females, two males: mean age 37 years); five had a history of aplastic anemia and three (one with and two without aplastic anemia) had severe hemolytic PNH and elevated plasma lactate dehydrogenase. PNH clone sizes at diagnosis were low in patients with less severe clinical symptoms (0.41-9.7% of granulocytes) and high in patients with severe symptoms (58-99%). There were only minimal differences in the follow-up clone size measurement for each patient between the six laboratories, particularly in those with high values at diagnosis.

CONCLUSIONS

The ICCS-recommended high-sensitivity flow cytometry protocol was effective for detecting major and minor PNH clones in Russian PNH patients, and showed high reproducibility between laboratories.

Detection of paroxysmal nocturnal hemoglobinuria clones to exclude inherited bone marrow failure syndromes

BACKGROUND

Inherited bone marrow failure syndromes (IBMFS) and acquired aplastic anemia (AA) are life-threatening marrow failure disorders. These entities can be difficult to distinguish because they present similarly. Correct diagnosis is imperative for proper therapy.

DESIGN AND METHODS

This is a retrospective, single-center study of patients <40 yr of age, evaluated for bone marrow failure, and assayed for the presence of a PNH clone in the pediatric or adult hematology/oncology clinics from 2001 to present. Patients were also evaluated for IBMFS.

RESULTS

We present results from 156 patients with marrow failure, 20 of whom have IBMFS. None of the IBMSF patients had paroxysmal nocturnal hemoglobinuria (PNH) clones.

CONCLUSIONS

Although further studies are needed, our results suggest that the detection of a PNH clone can be a useful diagnostic tool to exclude the diagnosis of IBMFS and focus the work-up and treatment on an acquired form of marrow failure.

The presence of CD55- and/or CD59-deficient erythrocytic populations in patients with rheumatic diseases reflects an immune-mediated bone-marrow derived phenomenon

Background

Complement has the potential to provoke severe impairment to host tissues, as shown in autoimmune diseases where complement activation has been associated with diminished CD55 and/or CD59 expression on peripheral blood cell membranes. The aim of this study was to evaluate the presence of CD55- and/or CD59-deficient erythrocytic populations in patients with different rheumatic diseases and to investigate possible correlations with clinical or laboratory parameters.

Material/Methods

CD55 and CD59 expression was evaluated in erythrocytes of 113 patients with rheumatic diseases, 121 normal individuals, and 10 patients with paroxysmal nocturnal hemoglobinuria (PNH) using the Sephacryl gel microtyping system. Ham and sucrose tests were also performed.

Results

Interestingly, the majority of patients (104/113, 92%) demonstrated CD55- and/or CD59-deficient erythrocytes: 47 (41.6%) with concomitant deficiency of CD55 and CD59, 50 (44.2%) with isolated deficiency of CD55, and 6 (6.2%) with isolated deficiency of CD59. In normal individuals, only 2 (1%) had concomitant CD55/CD59 negativity and 3 (2%) had isolated CD55 or CD59 deficiency. All PNH patients exhibited simultaneous CD55/CD59 deficiency. Positive Ham and sucrose tests were found only in PNH patients. There was no association between the CD55- and/or CD59-deficient erythrocytes and hemocytopenias or undergoing treatment. However, CD55 expression significantly influenced hemoglobin values (F=6.092, p=0.015).

Conclusions

This study provides evidence supporting the presence of erythrocytes with CD55 and/or CD59 deficiency in patients with rheumatic diseases. Moreover, CD55 deficiency on red cells influences hemoglobin concentration. Further studies using molecular techniques will clarify the exact pathophysiological mechanisms of this deficiency.

Effectiveness and safety of rabbit anti-thymocyte globulin in Japanese patients with aplastic anemia

Immunosuppressive therapy (IST) with antithymocyte globulin (ATG) and cyclosporine A is the standard treatment for aplastic anemia (AA). The ATG formulation in Japan was changed from horse ATG [Lymphoglobulin(®) (LG)] to rabbit ATG [Thymoglobulin(®) (TG)] in 2009. Since then, 12 patients with AA have been treated with TG. Here, we summarize the effectiveness and safety of TG in comparison with data from 14 AA patients treated with LG before April 2009. One subject treated with LG but none treated with TG terminated the treatment due to a grade III adverse effect. The overall 6-month response rate after IST was similar for LG and TG (67 and 75 %). Infection was noted in five (38 %) and four (33 %) subjects treated with LG and TG, respectively. The initial response rate was significantly higher in the early-treatment group treated within a year of diagnosis than in the late-treatment group, who were treated more than a year after diagnosis (85 vs. 29 %, respectively), as reported previously, without apparent differences between the LG and TG groups. We conclude that TG at a dose of 2.5 mg/kg/day for 5 days is effective and safe in Japanese patients with AA.

Prognostic value of telomere attrition in patients with aplastic anemia

The decision to pursue hematopoietic stem cell transplantation or immunosuppression as first therapy in severe aplastic anemia is currently based on age and availability of a histocompatible donor. The ability to predict hematologic response, relapse and clonal evolution could improve treatment allocation. In the past 15 years, telomeres have been implicated in clinical diseases such as aplastic anemia, pulmonary fibrosis, cirrhosis and cancer development. The clinical relevance of varying telomere lengths (TL) and/or mutations in genes of the telomerase complex (TERC, TERT) is evolving in aplastic anemia. A large retrospective analysis suggests that baseline TL associate with late events of hematologic relapse and clonal evolution in aplastic anemia patients treated initially with anti-thymocyte globulin-based therapy. Further laboratory experiments propose possible mechanistic insight into genomic instability of bone marrow cells derived from patients with critically short telomeres and/or mutation in telomerase genes. The possibility of modulating telomere attrition rate with sex hormones could positively affect clonal evolution rates in humans. This review will summarize studies in marrow failure that explore the association between telomeres and aplastic anemia outcomes.

Border between aplastic anemia and myelodysplastic syndrome

Distinguishing between acquired aplastic anemia (AA) and myelodysplastic syndrome (MDS) with a low blast cell percentage is often difficult and problematic, as both diseases are syndromes primarily defined by morphological findings, and their diagnostic criteria do not necessarily reflect the pathophysiology of their bone marrow (BM) failure. As a result, many patients with benign BM failure that should be managed as AA are diagnosed as having MDS, due to the absence of BM hypocellularity and the presence of dysplastic signs in the BM, and are treated inappropriately with toxic therapies, such as hypomethylating agents, and stem cell transplantation from unrelated donors. BM failure syndromes need to be managed in ways appropriate to their pathophysiology, which is more accurately determined by using markers such as the presence of glycosylphosphatidylinositol-anchored protein-deficient cells and HLA-A lacking leukocytes. We recently found that plasma thromobopoietin level is one of the most useful markers for distinguishing benign and pre-leukemic BM failure syndromes.

Standardization of flow cytometry in myelodysplastic syndromes: a report from an international consortium and the European LeukemiaNet Working Group

Flow cytometry (FC) is increasingly recognized as an important tool in the diagnosis and prognosis of myelodysplastic syndromes (MDS). However, validation of current assays and agreement upon the techniques are prerequisites for its widespread acceptance and application in clinical practice. Therefore, a working group was initiated (Amsterdam, 2008) to discuss and propose standards for FC in MDS. In 2009 and 2010, representatives from 23, mainly European, institutes participated in the second and third European LeukemiaNet (ELN) MDS workshops. In the present report, minimal requirements to analyze dysplasia are refined. The proposed core markers should enable a categorization of FC results in cytopenic patients as 'normal', 'suggestive of', or 'diagnostic of' MDS. An FC report should include a description of validated FC abnormalities such as aberrant marker expression on myeloid progenitors and, furthermore, dysgranulopoiesis and/or dysmonocytopoiesis, if at least two abnormalities are evidenced. The working group is dedicated to initiate further studies to establish robust diagnostic and prognostic FC panels in MDS. An ultimate goal is to refine and improve diagnosis and prognostic scoring systems. Finally, the working group stresses that FC should be part of an integrated diagnosis rather than a separate technique.

Multiparameter flow cytometry for the diagnosis and monitoring of small GPI-deficient cellular populations

BACKGROUND

Glycosyl-phosphatidylinositol (GPI)-negative blood cells are diagnostic for Paroxysmal Nocturnal Hemoglobinuria (PNH). Marrow failure states are often associated with GPI-negative cell populations. Quantification of small clonal populations of GPI-negative cells influences clinical decisions to administer immunosuppressive therapy in marrow failure states (aplastic anemia or myelodysplastic syndrome) and to monitor minimal residual disease after allogeneic blood or marrow transplantation (BMT). We studied the reliability of high-resolution flow cytometry markers operating at the limits of detection.

METHODS

We performed serial quantification of the PNH clone size in 38 samples using multiparameter flow cytometry. Granulocytes, monocytes, and RBCs were gated using forward and side scatter as well as lineage-specific markers. The GPI-linked markers fluorescent aerolysin (FLAER), CD55, and CD59 were comparatively evaluated. We also evaluated CD16 on granulocytes and CD14 on monocytes. The sensitivity of detection by each marker was further defined by serial dilution experiments on a flow-sorted sample. Two patients had quantification of their GPI-negative clones before and after allogeneic BMT.

RESULTS

FLAER was the most discriminant marker and allowed identification of 0.1% of GPI-negative cells despite other markers having superior signal-to-noise characteristics. CD14 and CD16 were inferior to CD55 at lower concentrations and in clinical application.

CONCLUSIONS

Multiparameter flow cytometry permits quantification of small GPI-negative clones with a sensitivity limit of about 0.1%. The single most reliable marker to monitor small granulocyte or monocyte PNH clones is FLAER, especially in conditions such as myelodysplastic syndromes or BMT, when traditional GPI-linked surface marker expression can be significantly altered. © 2010 International Clinical Cytometry Society.

Development of paroxysmal nocturnal haemoglobinuria in systemic lupus erythematosus: an unusual cause of portal vein thrombosis

We report a case of a 60 year-old female with systemic lupus erythematosus (SLE) who was being managed with low-dose oral prednisolone. Four years later, she was admitted with pain in upper abdomen of 1 week duration. It was associated with ascitis and thrombocytopenia. Radiological investigations revealed portal vein thrombosis. There were no known local thrombophilic risk factors. Investigations ruled out any associated inherited or acquired hypercoagulable states. To evaluate the cause of thrombocytopenia, bone marrow aspiration was performed. Cells were subjected to flow cytometric examination, which revealed deficiency of CD55 and CD59 on granulocytes, indicating that a clone of cells with paroxysmal nocturnal haemoglobinuria had developed in this patient which had resulted in portal vein thrombosis. At this juncture, Ham test was also positive. The importance of considering rare possibilities of thrombosis at unusual site in patients with SLE is highlighted.

Antibodies to glycosylphosphatidyl-inositol anchored proteins (GPI-AP) in antithymocyte and antilymphocyte globulin: possible role for the expansion of GPI-AP deficient cells in aplastic anemia

Antithymocyte globulin (ATG) and antilymphocyte globulin (ALG) are currently used successfully for immunosuppressive treatment of aplastic anemia. In this study we have investigated whether commercial ATG/ALG preparations contain antibodies against glycosylphosphatidyl-inositol anchored proteins (GPI-AP), which could be responsible for emergence of GPI-deficient populations in aplastic anemia after ATG/ALG therapy. We analyzed four commercial ATG/ALG preparations by competitive binding assays using flow cytometry. Quantification was achieved by calculating the concentration of ATG/ALG required to give 50% inhibition of binding the specific fluorochrome-labeled monoclonal antibody (EC50). High concentrations of antibodies against the GPI-anchored protein CD52 were found in all preparations (Lymphoglobulin Genzyme, Thymoglobulin Genzyme, ATGAM. Pharmacia & Upjohn, and ATG-Fresenius S Fresenius). Antibodies against the GPI-anchored protein CD48 are present in significant concentrations except in the preparation ATGAM. CD16 antibodies were found in lower concentrations. We could not detect significant concentrations of antibodies against the GPI-anchored proteins CD157 and CD14. Campath-1H, a monoclonal antibody against the GPI-anchored protein CD52, has been used as immunosuppressive tool for T-cell depletion. CD52 antibodies in ATG/ALG preparations might contribute in the same way to the immunosuppressive effects in treatment of aplastic anemia. It is known that in a substantial proportion of patients with aplastic anemia GPI-deficient cells are present in a low level at diagnosis or emerge after immunosuppressive therapy. GPI-anchored antibodies in ATG/ALG preparations might lead to a relative advantage for pre-existing GPI-deficient cells caused by an escape from the antibody-mediated attack.

Transient severe pancytopenia due to elevated tumor necrosis factor-alpha in overwhelming infection

A 66-year-old woman complained of fever, sore throat, and neck pain due to pharyngitis and painful lymph node swelling. CBC revealed severe pancytopenia and markedly hypocellular marrow. The administration of antibiotics and granulocyte-colony stimulating factor (G-CSF) successfully ameliorated the inflammatory lesions, and hematopoiesis recovered. Causes for pancytopnenia was unlikely to be virus infection or drugs, and aplastic anemia was also unlikely since only the plasma levels of tumor necrosis factor-alpha (TNF-alpha) was markedly elevated, erythropoietin (EPO) was slightly elevated, interferon-gamma (IFN-gamma) was normal, and flow cytometric analysis for paroxysmal nocturnal hemoglobinuria (PNH)-type cells was negative. These results suggested that the cause of impaired hematopoiesis in the present patient might have been due to elevated TNF-alpha in overwhelming infection, although the pathogen was not identified.

Detection of paroxysmal nocturnal hemoglobinuria clones in patients with myelodysplastic syndromes and related bone marrow diseases, with emphasis on diagnostic pitfalls and caveats

BACKGROUND

The presence of paroxysmal nocturnal hemoglobinuria clones in the setting of aplastic anemia or myelodysplastic syndrome has been shown to have prognostic and therapeutic implications. However, the status of paroxysmal nocturnal hemoglobinuria clones in various categories of myelodysplastic syndrome and in other bone marrow disorders is not well-studied.

DESIGN AND METHODS

By using multiparameter flow cytometry immunophenotypic analysis with antibodies specific for four glycosylphosphatidylinositol-anchored proteins (CD55, CD59, CD16, CD66b) and performing an aerolysin lysis confirmatory test in representative cases, we assessed the paroxysmal nocturnal hemoglobinuria-phenotype granulocytes in 110 patients with myelodysplastic syndrome, 15 with myelodysplastic/myeloproliferative disease, 5 with idiopathic myelofibrosis and 6 with acute myeloid leukemia.

RESULTS

Paroxysmal nocturnal hemoglobinuria-phenotype granulocytes were detected in nine patients with low grade myelodysplastic syndrome who showed clinicopathological features of bone marrow failure, similar to aplastic anemia. All paroxysmal nocturnal hemoglobinuria-positive cases demonstrated loss of the four glycosylphosphatidylinositol-anchored proteins, with CD16(-)CD66b(-) clones being larger than those of CD55(-)CD59(-) (p<0.05). Altered glycosylphosphatidylinositol-anchored protein expression secondary to granulocytic hypogranulation, immaturity, and/or immunophenotypic abnormalities was present in a substantial number of cases and diagnostically challenging.

CONCLUSIONS

These results show that routine screening for paroxysmal nocturnal hemoglobinuria clones in patients with an intrinsic bone marrow disease who show no clinical evidence of hemolysis has an appreciable yield in patients with low grade myelodysplastic syndromes. The recognition of diagnostic caveats and pitfalls associated with the underlying intrinsic bone marrow disease is essential in interpreting paroxysmal nocturnal hemoglobinuria testing correctly. In our experience, the CD16/CD66b antibody combination is superior to CD55/CD59 in screening for subclinical paroxysmal nocturnal hemoglobinuria because it detects a large clone size and is less subject to analytical interference.

Allogeneic stem cell transplantation for aplastic anemia

Aplastic anemia encompasses a heterogeneous group of diseases with distinct pathophysiologies and a common clinical endpoint of marrow failure. Patients with severe aplastic anemia can be treated with immunosuppressive therapy (IST) or hematopoietic stem cell transplantation (HSCT). Over the last 30 years, advances in both treatment modalities have significantly improved the prognosis for this disease; yet this evolution complicates the central therapeutic question in aplastic anemia: which patients should receive IST and which ones should receive HSCT as front-line therapy? In this review, we describe the major improvements that have occurred in transplantation for aplastic anemia in the last 3 decades. We then outline a framework for deciding which patients should be considered for upfront transplantation.