Paroxysmal Nocturnal Hemoglobinuria Screening Research Articles

Diagnostic landscape of first-time cytometric screening for paroxysmal nocturnal hemoglobinuria in Poland in 2013–2022

BackgroundParoxysmal nocturnal hemoglobinuria (PNH) is an acquired hematopoietic stem cell disorder characterized by PIG-A mutations, leading to glycophosphatidylinositol (GPI)-anchored proteins deficiency that triggers hemolysis – a hallmark of the disease. PNH diagnostics is based on high-sensitivity multicolor flow cytometry (MFC), enabling to detect even small populations of PNH cells. In this single-center, retrospective study, we aimed to characterize a cohort of PNH clone-positive patients first time screened from January 1st, 2013 until December 31st, 2022 with MFC according to International Clinical Cytometry Society PNH Consensus Guidelines.ResultsOut of 2790 first-time screened individuals, the presence of PNH clone in neutrophils was detected in 322 patients, including 49 children and 273 adults. Annual incidence was stable at a median of 31 patients (14 and 19 with clone sizes ≤ 1% and > 1%, respectively), with a decline in number of patients with clone sizes > 1% observed in 2020, potentially influenced by the COVID-19 pandemic. The most common screening indications were aplastic anemia and other cytopenias.ConclusionsA significant underrepresentation of hemolytic patients was observed as compared to the published cohorts suggesting that these patients are missed in diagnostic process and classic PNH remains underdiagnosed in Poland.

CD16-56/SSC plot in routine flow: A resource for screening of paroxysmal nocturnal Hemoglobinuria?

CD16-56/SSC plot in routine flow: A resource for screening of paroxysmal nocturnal Hemoglobinuria?

Expert consensus on clonal screening and monitoring of complement inhibitor therapy in paroxysmal nocturnal hemoglobinuria (2024)

Paroxysmal nocturnal hemoglobinuria (PNH) is a rare clonal disease with abnormal hematopoietic stem cells that causes intravascular hemolytic anemia, thrombosis, and peripheral blood cytopenia. It has a chronic progressive course and can be fatal in severe cases if not treated aggressively. Complement inhibitors are the first-line recommended treatment for hemolysis-related symptoms of PNH. With the rapid development of new complement inhibitors, it is critical to quickly screen and confirm the diagnosis, identify patients with complement inhibitor indications, and monitor breakthrough hemolysis and extravascular hemolysis during complement inhibitor therapy. Drawing on the most recent guidelines, works of literature, and meta-reviews from around the world, as well as combining with experience from the experts, this consensus focused on PNH screening principles, the significance of PNH cloning detection, and post-treatment monitoring of terminal complement inhibitors, which may contribute to a better understanding of diagnosis and treatment monitoring in the era of complement inhibitors.

Frequency of Paroxysmal Nocturnal Hemoglobinuria in Patients with Lymphoma

Objective: To investigate the frequency of paroxysmal nocturnal hemoglobinuria (PNH), an acquired clonal hematopoietic stem cell disease resulting in complement-mediated hemolysis, in patients with lymphoma by flow cytometry.Methods: Fifty patients with lymphoma who were admitted to the hematology clinic, newly diagnosed and not yet treated were included in this study conducted in 2014. The presence of PNH clones was checked by FLAER flow cytometry method in peripheral blood samples. FLAER is a non-hemolytic fluorescently labeled inactive toxin aerolysin method that can detect up to 0.5% of PNH cells instead of bacterial toxin aerolysin, which binds to RBCs via the GPI anchor and initiates hemolysis for PNH screening or PNH clone detection. With this technique, PNH clones in all hematopoietic cell lines can be detected in an assay.Results: PNH clone was observed over 10% in two patients, one male and the other female. However, no hemolysis was found in patients with PNH clones. The lymphoma subtypes of the patients with positive PNH clone were B-cell small-cell lymphocytic lymphoma in the male patient and primary splenic lymphoma in the female patient.Conclusion: PNH or PNH-like disorders accompanying hematological malignancies, especially lymphomas, are not very common in the literature. There is a need to elucidate the relationship between hematological malignancies and PNH with the help of more advanced molecular techniques.

FLAER‐negative CD15+ neutrophils can be used for the simplified screening of suspected PNH cases

The flow cytometry analysis of GPI-linked proteins on red blood cells and leukocytes is crucial for paroxysmal nocturnal hemoglobinuria (PNH) diagnostics. However, the commonly used multicolor panels cannot be implemented in low-resourced hematology laboratories. In order to develop a simple prediagnostic test for PNH screening, we analyzed the diagnostic accuracy of the two-color (FLAER/CD15) detection of GPI-deficient neutrophils. We reanalyzed multicolor data set of 1594 peripheral blood samples of patients screened for PNH applying only two markers (FLAER/CD15). The quantitative positivity/negativity was reported. Then, these results were compared in a blinded manner with previously obtained multicolor data from the same samples. Among the 1594 samples included in the study, 507 samples were PNH-positive by the multicolor assay. The two-color method revealed 510 PNH-positive samples. The detailed examination of this discrepancy revealed 12 false-positives and 9 false-negatives. Therefore, FLAER/CD15 screening method displayed 98.90% of the diagnostic specificity and 98.22% of the sensitivity. This simple two-color evaluation of FLAER-negative neutrophils is a highly effective screening test for PNH. Although this approach is not intended to replace the multicolor diagnostic procedure, it could minimize the number of patients requiring a conventional multicolor flow cytometric assay.

Study for the Diagnostic Screening of Paroxysmal Nocturnal Hemoglobinuria in Older Patients with Unexplained Anemia and/or Cytopenia.

Paroxysmal nocturnal hemoglobinuria (PNH) is a rare acquired hematopoietic stem cell disease that may lead to weakness and death of patients, if unrecognized and untreated. Although consensus guidelines were reviewed recently for the diagnostic screening of PNH with multi-parameter flow cytometry (FCM), until now, no study has investigated the efficiency of such clinical indications in older patients. Overall, 20 centers participated in the study and a total of 1,689 patients were included, 313 of whom were at geriatric age and 1,376 were aged 18 - 64 years. We evaluated the efficiency of consensus clinical indications for PNH testing using FCM in peripheral blood samples and compared the results of older patients and patients aged 18 - 64 years. PNH clones were detected positive in 7/313 (2.2%) of the older patients. Five (74.4%) of the patients with PNH clones had aplastic anemia, 1 had unexplained cytopenia, and 1 patient had myelodysplastic syndrome (MDS) with refractory anemia. PNH clones were not detected in any older patients who were screened for unexplained thrombosis, Coombs (-) hemolytic anemia, hemoglobinuria, and others (e.g., elevated lactate dehydrogenase (LDH), splenomegaly). We detected PNH clones in 55/1376 (4%) samples of the patients aged under 65 years. Forty-two (76.4%) patients with PNH clones had aplastic anemia, 2 patients had Coombs (-) hemolytic anemia, 3 patients had unexplained cytopenia, 1 patient had MDS with refractory anemia, 1 patient had hemoglobinuria, and 6 (10.9%) had others (e.g., elevated LDH, splenomegaly). PNH clones were not detected in any patients who were screened for unexplained thrombosis. There was no statistical difference between the geriatric population and patients aged 18 - 64 years in terms of clinical indications for PNH screening with FCM (p = 0.49). Our results showed that the current clinical indications for PNH screening with FCM were also efficient in older patients. We suggest that older patients with unexplained anemia, myelodysplastic syndrome with refractory anemia, and unexplained cytopenia should be screened for PNH with FCM to identify patients who would benefit from treatment.

Screening for paroxysmal nocturnal hemoglobinuria (PNH) in patients presenting with cerebral sinovenous thrombosis (CSVT): Results of a FLAER based flowcytometry study in Indian patients.

Patients with paroxysmal nocturnal hemoglobinuria (PNH) may present with thrombosis at unusual sites, of which cerebral sinovenous thrombosis (CSVT) is one and screening for PNH is recommended in this condition. Though many patients diagnosed with PNH develop CSVT, it is unclear how many patients with PNH would present for the first time with thrombosis. We analysed the results of screening for PNH by flowcytometry in our patients with CSVT. The laboratory data of patients referred for thrombophilia and PNH testing in CSVT was examined to assess the frequency of PNH at presentation in these patients. FLAER and CD24 on granulocytes and FLAER and CD14 on monocytes respectively were used to screen the leucocytes for PNH by flowcytometry. The data for Protein C, S and Antithrombin deficiency, antiphospholipid antibodies and the Factor V Leiden mutation was examined and circumstantial risk factors were also assessed. Of the 180 cases of CSVT screened by flowcytometry for PNH, not a single case tested positive. Positivity for anti-phospholipid antibodies was the most common thrombophilic risk factor (5%). Pregnancy was the most common circumstantial risk factor. Our data on FLAER based flowcytometry in the North Indian population with CSVT suggests that PNH is not a common risk factor in our patients with thrombosis at this unusual site.

Screening and diagnostic clinical algorithm for paroxysmal nocturnal hemoglobinuria: Expert consensus.

Paroxysmal nocturnal hemoglobinuria (PNH) is a severe, life-threatening disorder for which early diagnosis is essential. However, given the rarity of the disease and non-specificity of symptoms, correct diagnosis may be delayed or missed. While various hematologic guidelines note common signs and symptoms associated with PNH, international expert consensus based on real-world clinical experience and an actionable algorithm for non-specialists to facilitate screening and diagnosis are lacking. The objective of the study is to develop a clinically relevant, consensus-driven screening and diagnostic algorithm on PNH for non-specialist clinicians. An expert advisory committee of PNH experts from North America, Europe, and Japan was convened, and a modified Delphi methodology was employed to develop an algorithm to assist non-specialist clinicians in identifying signs/symptoms of PNH and conducting appropriate differential diagnosis. Twelve globally representative Delphi panelists with clinical expertise in PNH were identified and recruited. Panelists provided their differential diagnosis for 5 blinded case studies via 2 rounds of online questionnaires. Responses mentioned by >50% of panelists in the first round were included in the second-round questionnaire, at which point consensus was attained if >80% of panelists agreed on an approach. Consensus was reached for 95% of screening and diagnostic decision points and 90% of tests required at decision points. These results facilitated development of a consensus-based, clinically relevant algorithm, providing non-specialist clinicians with actionable guidance on PNH screening and diagnosis.

Hemolytic anemia, iron deficiency and personal history of deep vein thrombosis: consider paroxysmal nocturnal hemoglobinuria

Paroxysmal nocturnal hemoglobinuria (PNH) is a rare acquired hematopoietic stem cell disorder that must be correctly diagnose because it is a chronic disease with a real impact on the quality of life and the survival of the patients. PNH screening of all patients with anemia or thrombosis is not recommended. We report the case of a 71-year-old male patient referred for chronic anemia. Anemia work-up revealed a misunderstood association of a hemolytic anemia with a negative direct antiglobulin test and iron deficiency. The patient exhibits biological signs of intravascular hemolysis, as well as a recent history of two episodes of deep vein thrombosis. Screening for PNH by flow cytometry shown a PNH clone with a size of approximately 33% of the granulocytes and 11% of the red blood cells. An interstitial deletion of the chromosome 13 was found in the medullar karyotype. PNH through chronic intravascular hemolysis induces an urinary iron loss. This is the only cause of hemolytic anemia inducing iron deficiency.

Utility of CD157 as a Common Leukocytes Marker for Paroxysmal Nocturnal Hemoglobinuria Screening in a Single Tube Five Color Combination

To study the utility and advantage of CD157 in the paroxysmal nocturnal hemoglobinuria (PNH) screening along with its ability to replace CD24 and CD14. This was a confirmatory study to analyse the role and advantage of CD157 in a single tube five color combination to identify the PNH clones. A serial tenfold dilution experiments was carried out for sensitivity assessment. Reproducibility was checked in the intra-assay and inter-assay experiments. The results obtained with CD157 based assay were compared with the routinely used single tube six color CD24/CD14 based assay. CD157 showed a high degree of sensitivity at the level of 10-4. PNH positive clone sizes were precise with CVs of inter-assay and intra-assay precision analysis for polymorphs/monocytes ranging from 2.94 to 4.31/2.52 to 8.93, and 0.91 to 3.23/1.65 to 5.33%; respectively. The results were similar to those obtained from CD24/CD14 based assay (R2>0.993). There was no false positive or false negative result. CD157 was found better in delineating the type II clones. CD157 can be used as a common PNH leucocyte marker with high degree of sensitivity and precision. It can replace CD24 and CD14 from the currently used assays and thus bring down the cost of PNH screening.

Multicenter validation of a simplified method for paroxysmal nocturnal hemoglobinuria screening.

Paroxysmal nocturnal hemoglobinuria (PNH) diagnostic guidelines recommend single-tube five- to six-color or two-tube four-color assays. PNH clones are detectable in only a fraction of patients at risk, and screening for new PNH cases can be complex and expensive. In this multicenter study, we have validated a simplified, one-tube two-color FLAER-based assay suitable for PNH screening. Six laboratories received samples containing spiked PNH leukocyte clones to be analyzed in parallel with a common six-color cocktail (FLAER/CD24/CD45/CD64/CD15/CD14) and a simplified two-color mixture (FLAER/CD15), a shared calibration procedure, and a common analysis protocol. Replicate precision and sensitivity tests were performed on PNH patients, from undiluted to 1:10000. Specificity tests were performed on normal donors to identify the possible sources of artifacts. The performance comparison between six-color and two-color assays showed an excellent agreement for granulocyte PNH clones. Dilution experiments showed an accurate detectability down to 0.01% sensitivity level for granulocyte PNH clones and to 1% for monocytes. Specificity experiments disclosed that basophils and platelets can contaminate the monocyte gate and generate false PNH events. A simplified two-color (FLAER/CD15) PNH screening test has been validated in a highly standardized multicenter study and proved feasible and effective in ongoing regional programs. Precision, sensitivity, and specificity of the simplified test for granulocytes were comparable to the more complex and expensive six-color assay and applicable for screening also in peripheral laboratories. The diagnostic confirmation of PNH should be always performed by a reference center using the established technique on all cell lineages.

A retrospective study of paroxysmal nocturnal hemoglobinuria in pediatric and adolescent patients

Paroxysmal nocturnal hemoglobinuria (PNH) is a rare disease, especially in children, characterized by intravascular hemolysis, thrombotic events, serious infections and bone marrow failure. We describe 16 patients who were diagnosed with PNH in childhood or adolescence. The time interval between the onset of symptoms and the PNH diagnosis and its treatment were compared in patients with classic PNH versus PNH associated with bone marrow disorder (PNH/BMD). A greater delay in diagnosis was observed in classic PNH compared to PNH/BMD patients. The first group of patients had higher levels of LDH, total bilirubin and absolute reticulocyte count and a bigger PNH clone size compared to PNH/BMD patients; also thrombotic events were observed only in the classic form of PNH. Conversely, PNH/BMD patients showed lower median levels of platelets. Apart from standard supportive measures, four patients with classic PNH received eculizumab whereas four patients with PNH/BMD underwent hematopoietic stem cell transplantation. Our series confirm that the most frequent presentation of PNH in the pediatric-adolescent age is PNH/BMD. The delay between the onset of symptoms and PNH diagnosis is relevant principally in the classic form. Moreover, our study showed that any case of unexpected thrombosis represents a criterium to perform a PNH screening.

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

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. 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. 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%). 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.

Flow cytometry screening for paroxysmal nocturnal hemoglobinuria: A single-center experience in Saudi Arabia.

Paroxysmal nocturnal hemoglobinuria (PNH) is a rare acquired clonal hematopoietic stem cell disorder, characterized by the deficiency of glycosylphosphatidylinositol (GPI) that anchors proteins in cell membranes. PNH is manifest variously with hemoglobinuria, thrombosis, or bone marrow failure. This retrospective study was aimed at assessing the incidence and characteristics of patients diagnosed with PNH in the King Fisal Specialist Hospital and research center. Patients referred for PNH diagnosis at King Faisal Specialist Hospital and Research Centre, Riyadh, during the 2-year period (2012-2013) were included in the analysis. Peripheral blood samples were used for multi-parametric flow cytometry analysis based on fluorescent inactive aerolysin (FLAER), and the markers, CD235a and CD59 on red blood cells (RBCs), and CD14, CD45, CD64, CD24, and CD15 on white blood cells (WBCs) exclusively monocytes and granulocytes. Univariate analysis of the disease characteristics was performed. Of the 366 samples submitted for PNH screening, 14 were positive (4%) and 11 were evaluable. Of the 11 patients analyzed, 8 patients (73%) presented with aplastic anemia, 1 patient (9%) each with pancytopenia, Budd-Chiari syndrome, and immune thrombocytopenia purpura. All samples showed type II and III GPI-deficient clones with a median clone size of 15% (range, 0.7%-56%) in the RBCs, and 63% (range, 3.8%-100%) in WBCs (monocytes and granulocytes). This study confirms the rarity of PNH and its predominant presentation as aplastic anemia or thrombosis in a Saudi Arabian population, similar to the worldwide incidence.

Frequency of Paroxysmal Nocturnal Hemoglobinuria Clones by Multiparametric Flow Cytometry in Pediatric Aplastic Anemia Patients of Indian Ethnic Origin.

The literature on paroxysmal nocturnal hemoglobinuria (PNH) in aplastic anemia (AA) is largely focused on adults with few studies in children. Moreover, large studies are conspicuously absent from developing countries. Knowledge of the prevalence and utility of their detection is required before widespread use of PNH screening in pediatric AA in resource-limited settings. We performed a retrospective audit over a period of 9 years to study the prevalence of PNH clones by flow cytometry (FCM) in children ≤12 years of age presenting with AA, and analyzed their response to immunosuppressant therapy. Nine (12.9%) out of 70 patients had PNH clones comprising >1% of the target cell population, including five patients (7.14%) with PNH clone size >10%. The clone size in monocytes ranged from 3.7% to 95.2% (median 21.1%) and in neutrophils from 1.6% to 87.6% (median 19.5%). Fluorescent aerolysin (FLAER)-based FCM screening significantly improved the detection of PNH clones compared to non-FLAER based screening techniques (18.4% vs. 6.25%). One child showed chronic intravascular hemolysis and another developed arterial stroke during the course of illness. None of our PNH-positive AA patients tested for chromosome breakage studies (n = 8) showed increased clastrogen-induced breakage. A lower frequency but moderate/large-sized PNH clones were seen in our pediatric AA population, compared to western data. FLAER-based FCM screening significantly improved the detection of PNH clones. We recommend routine FLAER-based screening of PNH in pediatric AA patients.

A novel marker for screening paroxysmal nocturnal hemoglobinuria using routine complete blood count and cell population data.

BackgroundFinal diagnosis of paroxysmal nocturnal hemoglobinuria (PNH) may take years demanding a quick diagnosis measure. We used the facts that PNH cells are damaged in acid, and reagents for measuring reticulocytes in Coulter DxH800 (Beckman Coulter, USA) are weakly acidic and hypotonic, to create a new PNH screening marker.MethodsWe analyzed 979 complete blood counts (CBC) data from 963 patients including 57 data from 44 PNH patients. Standard criteria for PNH assay for population selection were followed: flow cytometry for CD55 and CD59 on red blood cells (RBCs) to a detection level of 1%; and fluorescent aerolysin, CD24 and CD15 in granulocytes to 0.1%. Twenty-four PNH minor clone-positive samples (minor-PNH+) were taken, in which the clone population was <5% of RBCs and/or granulocytes. Excluding PNH and minor-PNH+ patients, the population was divided into anemia, malignancy, infection, and normal groups. Parameters exhibiting a distinct demarcation between PNH and non-PNH groups were identified, and each parameter cutoff value was sought that includes the maximum [minimum] number of PNH [non-PNH] patients.ResultsCutoff values for 5 selected CBC parameters (MRV, RDWR, MSCV, MN-AL2-NRET, and IRF) were determined. Positive rates were: PNH (86.0%), minor-PNH+ (33.3%), others (5.0%), anemia (13.4%), malignancy (5.3%), infection (3.7%), normal (0.0%); within anemia group, aplastic anemia (40.0%), immune hemolytic anemia (11.1%), iron deficiency anemia (1.6%). Sensitivity (86.0%), specificity (95.0%), PPV (52.1%), and NPV (99.1%) were achieved in PNH screening.ConclusionA new PNH screening marker is proposed with 95% specificity and 86% sensitivity. The flag identifies PNH patients, reducing time to final diagnosis by flow cytometry.

Usefulness of Screening for Paroxismal Nocturnal Hemoglobinuria in Patients with Undefined Anemia

Background: Paroxysmal nocturnal hemoglobinuria (PNH) is a rare life-threatening blood disease that is characterized by intravascular hemolytic anemia and thrombosis. It may be primary or secondary to other bone marrow diseases. It results from clonal expansion of a multipotent hematolopoietic stem cell harboring a PIG-A mutation. The PIG-A gene product is required for the biosynthesis of glycophosphatidylinositol anchors, a glycolipid moiety that tethers proteins to lipid bilayer of cell membranes. Consequently, the PNH stem cell and its progeny have a reduction or absence of all GPI-anchored proteins. Two of these proteins, CD55 and CD59, are complement regulatory proteins and are fundamental to the pathophysiology of paroxysmal nocturnal hemoglobinuria. CD55 inhibits C3 convertase and CD59 blocks the formation of the membrane attack complex (MAC). The loss of complement regulatory proteins renders PNH erythrocytes susceptible to both intravascular (due to CD59 deficiency) and extravascular (due to CD55 deficiency) hemolysis, but it is the intravascular hemolysis that contributes to much of the morbidity and mortality from the disease. Eculizumab is a humanized monoclonal antibody that is a terminal complement inhibitor and the first therapy approved for the treatment of PNH. In clinical trials in patients with PNH, eculizumab was associated with reductions in chronic hemolysis, thromboembolic events, and transfusion requirements, as well as improvements in PNH symptoms, quality of life, and survival. Methods: In a national observational study, 3162 patients with aplastic anemia, hemoglobinuria, myelodysplastic syndromes, undefined anemia, and atypical thrombosis have been evaluated for the PNH III clone. In a single center study in Reggio Calabria, Italy, 103 of the national registry patients were screened. Diagnostic flow cytometry for CD55 and CD59 on white and red blood cells was performed. Based on the levels of these cell proteins, cells may be classified as type I, II, or III PNH cells. Type I cells have normal levels of CD55 and CD59; type II have reduced levels; and type III have absent levels. Results: Of the national registry, 428 (13,5%) had GPI-linked defects. In the single center registry from Reggio Calabria, 3 cases (3%) with undefined anemia were identified as harboring the PNH III clone. Of the latter, at diagnosis, 2 patients had myelodysplastic syndromes and were red blood cell transfusion-dependent with high serum LDH levels (> 10 times upper normal limits) and one patient presented with cerebral venous thrombosis. They received Eculizumab according to international guidelines. The 2 patients with transfusion requirement obtained an erythroid response with transfusion independence with a significant decrease in serum LDH and the patient with cerebral thrombosis experienced complete recovery. Conclusions: PNH screening is useful among high risk populations. The identification of the PNH clone allows for targeted therapy to obtain clinically meaningful responses. DisclosuresOliva:Celgene: Consultancy, Honoraria; Novartis: Consultancy, Speakers Bureau.

Screening for Paroxysmal Nocturnal Hemoglobinurea with Cytodiff Analysis

Introduction. Paroxysmal nocturnal hemoglobinuria (PNH) is a rare hematopoietic stem cell disorder resulting from the somatic mutation of the X-linked phosphatidylinositolglycan complementation Class A (PIG-A) gene. PIGA mutations in PNH patients lead to a glycosylphosphatidylinositol (GPI)-linked membrane proteins expression deficiency.In PNH, there is a partial or absolute inability to make GPI-anchored proteins including complement-defense structures such as CD55 and CD59 on RBCs and WBCs. Clinical features of PNH include intravascular hemolysis, bone marrow failure, and thrombosis, all major causes of morbidity and mortality. Flow cytometry (FCM) plays a key role in the laboratory investigation of PNH, and rapid diagnosis of this condition is highly desirable. A definitive diagnosis of PNH can be established by demonstrating the absence of cell membraneGPI-anchored proteins from granulocytes or red blood cells (RBC) according to ICCS Guidelines for the diagnosis and monitoring of PNH by flow cytometry. It has been also described that the expression of CD16 can be decreased on PNH-affected granulocytes.Recently new method for extended flow WBC differential was introduced by Beckman Coulter. This method uses flow cytometric analysis with CytoDiff™** reagents which is a 5-color/6-marker reagent that provides a 10-part cytometric differential from whole blood specimens and comprises CD36-FITC, (CD2+CD294)-PE, CD19-ECD, CD16-PC5, and CD45-PC7 (Beckman Coulter).The protocol allows detection of mature neutrophils, total lymphocytes, total monocytes, eosinophils, basophils, immature granulocytes, B lymphocytes, CD16-negative T/NK lymphocytes, CD16-positive T/NK lymphocytes, CD16 positive and CD16 negative monocytes, and blasts cells with lineage orientation. This method also allows the detection of the abnormal antigen expression on WBC, for example low CD16 expression on neutrophils. In case of abnormal low CD16 expression on segmented neutrophils they will be classified as Immature Granulocytes (Imm Gran). The aim of the study was to evaluate the efficacy of CytoDiff** analysis of peripheral blood for PNH screening detecting low CD16 expression on neutrophils.Methods: EDTA-anticoagulated blood samples from 53 patients with PHN suspicion were prospectively included in the study. Analysis of the PNH clones was conducted in according with international protocol, using CD235a for RBC gating, CD15-PE/CD45-PC7 for granulocyte gating, CD64-PC5/CD45-PC7 for monocyte gating and GPI-anchored proteins CD59-PE, FLAER-FITC/CD24-PC5 and FLAER-FITC/CD14-PE for RBCs, granulocytes and monocytes accordingly.For extended flow WBC differential analysis the blood samples were stained with the CytoDiff** panel, lyzed with Versalyse (Beckman Coulter) and 20 000 leucocytes were analyzed on a FC500 Flow Cytometer (Beckman Coulter) using CytoDiff** CXP software.Results:Totally 53 patients with PHN suspicion were prospectively included in the study. All these patients were characterized by anemia, thrombocytopenia and/or leucopenia. PNH diagnosis was confirmed in 6 patients and in other 7 patients the final diagnosis was aplastic anemia with PNH clone.For all 13 patients (4 males, 9 females, with median age of 41.5 years) with confirmed presence of PNH clone CytoDiff** reported increased number of Imm Gran (range 3-45%). Microscopy analysis did not detect the presence of Imm Grans in the slide, so we concluded that falsely reported increased Imm Gran count was due to the decreased expression of CD16 on Neutrophils. Good correlation (r=0.9257) was observed between Imm Gran count and the size of granulocytic PNH clone.Conclusion: Our data demonstrate that CytoDiff** analysis, which is able to detect a wide spectrum of normal and pathological cells in peripheral blood allows determination of CD16-low expression on neutrophils and thus provide efficient screening for suspicious of PNH in patients with anemic syndrome.** Not available in the United States and other geographies. DisclosuresLugovskaya:Beckman Coulter: Research Funding.

Multiparameter FLAER-based flow cytometry for screening of paroxysmal nocturnal hemoglobinuria enhances detection rates in patients with aplastic anemia.

Flow cytometry is the gold standard methodology for screening of paroxysmal nocturnal hemoglobinuria. In the last few years, proaerolysin conjugated with fluorescein (FLAER) has become an important component of antibody panel used for the detection of paroxysmal nocturnal hemoglobinuria (PNH) clone. This study aimed to compare PNH clone detection by flow cytometry in the pre-FLAER era versus the FLAER era. This was a retrospective analysis of 4 years and included 1004 individuals screened for PNH clone, either presenting as hemolytic anemia or as aplastic anemia. In the pre-FLAER time period, the RBCs and neutrophils were screened with antibodies against CD55 and CD59. With the introduction of FLAER, neutrophils were screened with FLAER/CD24/CD15 and monocytes with FLAER/CD14/CD33 combination. A comparative analysis was done for detection of PNH clone in aplastic anemia patients versus non-aplastic anemia patients, as well as between pre-FLAER and FLAER era. Out of a total of 1004 individuals, 59 (5.8%) were detected to have PNH clone positivity. The frequency of PNH clone detected in aplastic anemia and non-aplastic anemia groups was 12.02 and 3.36%, respectively. The detection rate of PNH clone increased from 4.5% (32/711) in the pre-FLAER era to 9.2% (27/293) with the introduction of FLAER. However, this increase could be attributed to increased detection of PNH clone in the aplastic anemia group, which showed a significant increase from 8.3 to 18.2% after use of FLAER. In the non-aplastic group, PNH clone was detected with similar frequencies before and after use of FLAER (3.2 versus 3.8%, respectively). Mean PNH clone size was lower in the aplastic anemia group when compared with the non-aplastic group. RBCs always showed a lower clone size than neutrophils. PNH clone on neutrophils and monocytes was however similar. Inclusion of FLAER increases the sensitivity of the test which is especially useful in picking up small PNH clones in patients of aplastic anemia.

Prevalence of paroxysmal nocturnal hemoglobinuria in Chinese patients with Budd‐Chiari syndrome or portal vein thrombosis

Routine screening for paroxysmal nocturnal hemoglobinuria (PNH) in patients with Budd-Chiari syndrome (BCS) or portal vein thrombosis (PVT) has been recommended in Western countries. However, little is known about whether the routine screening test should be necessary in Chinese patients with BCS or PVT. We conducted a prospective observational study to examine the prevalence of PNH in these patients. Patients with primary BCS or non-malignant PVT who were consecutively admitted to our department or regularly followed up between September 2009 and December 2011 were eligible for the study and detected the expression of CD55 and CD59 on erythrocytes and granulocytes. The CD55 or CD59 deficiency was considered as the proportion of erythrocytes or granulocytes with normal expression of CD55 or CD59 was less than 90%. PNH was diagnosed by both CD55 and CD59 deficient clone at flow cytometry of peripheral blood cells. CD55 and/or CD59 deficiencies were found in 1.6% (2/127) of patients with primary BCS, 1.0% (1/100) of non-malignant and non-cirrhotic patients with PVT, and 4.7% (4/85) of cirrhotic patients with PVT. Only one patient had both CD55 and CD59 deficiencies on granulocytes. But he had been diagnosed with PNH before BCS. Paroxysmal nocturnal hemoglobinuria was very rare in Chinese patients with BCS or PVT, suggesting that routine screening for PNH should not be indiscriminately performed in such patients.