scholarly journals Update on the diagnosis and management of paroxysmal nocturnal hemoglobinuria

Hematology ◽  
2016 ◽  
Vol 2016 (1) ◽  
pp. 208-216 ◽  
Author(s):  
Charles J. Parker
Keyword(s):  
Bone Marrow ◽  
Paroxysmal Nocturnal Hemoglobinuria ◽  
Cell Clone ◽  
Bone Marrow Failure ◽  
Flow Cytometric Analysis ◽  
Disease Process ◽  
Hematopoietic Stem ◽  
Glycosyl Phosphatidylinositol ◽  
Flow Cytometric ◽  
Immune Mediated

Abstract Once suspected, the diagnosis of paroxysmal nocturnal hemoglobinuria (PNH) is straightforward when flow cytometric analysis of the peripheral blood reveals a population of glycosyl phosphatidylinositol anchor protein-deficient cells. But PNH is clinically heterogeneous, with some patients having a disease process characterized by florid intravascular, complement-mediated hemolysis, whereas in others, bone marrow failure dominates the clinical picture with modest or even no evidence of hemolysis observed. The clinical heterogeneity is due to the close, though incompletely understood, relationship between PNH and immune-mediated bone marrow failure, and that PNH is an acquired, nonmalignant clonal disease of the hematopoietic stem cells. Bone marrow failure complicates management of PNH because compromised erythropoiesis contributes, to a greater or lesser degree, to the anemia; in addition, the extent to which the mutant stem cell clone expands in an individual patient determines the magnitude of the hemolytic component of the disease. An understanding of the unique pathobiology of PNH in relationship both to complement physiology and immune-mediated bone marrow failure provides the basis for a systematic approach to management.

scholarly journals Paroxysmal Nocturnal Hemoglobinuria: An Underestimated Cause of Pediatric Thromboembolism

TH Open ◽  
2020 ◽  
Vol 04 (01) ◽  
pp. e36-e39
Author(s):  
Christina Griesser ◽  
Michael Myskiw ◽  
Werner Streif
Keyword(s):  
Paroxysmal Nocturnal Hemoglobinuria ◽  
Clinical Symptoms ◽  
Bone Marrow Failure ◽  
Flow Cytometric Analysis ◽  
Routine Diagnostics ◽  
Glycosyl Phosphatidylinositol ◽  
Vein Thrombosis ◽  
Flow Cytometric ◽  
Appropriate Treatment

AbstractParoxysmal nocturnal hemoglobinuria (PNH) is a chronic disease caused by complement-mediated hemolysis. Clinical symptoms include intravascular hemolysis, nocturnal hemoglobinuria, thromboses, cytopenia, fatigue, abdominal pain, and a strong tendency toward bone marrow failure. It is a rare disease, especially in children, with high mortality rates without appropriate treatment.We here present the case of a 17-year-old girl with unprovoked muscle vein thrombosis. Flow cytometric analysis showed deficiency of glycosyl-phosphatidylinositol-anchored membrane proteins on all three hematopoietic cell lines and confirmed the diagnosis of PNH. Treatment with the monoclonal antibody eculizumab achieved long-term remission.As flow cytometry is normally not part of the routine diagnostics for pediatric thrombosis, awareness is crucial and PNH is important to consider in all children with thrombosis at atypical sites and abnormalities in blood counts with regard to hemolysis and cytopenia.

Chronic RPS19 Deficiency Leads to Bone Marrow Failure In a Mouse Model for Diamond-Blackfan Anemia

Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 193-193
Author(s):  
Pekka Jaako ◽  
Johan Flygare ◽  
Karin Olsson ◽  
Ronan Quere ◽  
Jonas Larsson ◽  
...  
Keyword(s):  
Stem Cells ◽  
Bone Marrow ◽  
Bone Marrow Cells ◽  
Bone Marrow Failure ◽  
Flow Cytometric Analysis ◽  
Wild Type ◽  
Erythroid Progenitors ◽  
Hematopoietic Stem ◽  
Flow Cytometric

Abstract Abstract 193 Diamond-Blackfan anemia (DBA) is a congenital erythroid hypoplasia associated with physical malformations and predisposition to cancer. Of the many different DBA disease genes known, all encode for ribosomal proteins, suggesting that DBA is a disorder relating to ribosomal biogenesis or function. Among these genes, ribosomal protein S19 (RPS19) is the most frequently mutated (25 % of the patients). The generation of animal models for DBA is pivotal in order to understand the disease mechanisms and to evaluate novel therapies. We have generated two mouse models for RPS19-deficient DBA by taking advantage of RNA interference (Jaako et al, 2009 ASH meeting abstract). These models contain RPS19-targeting shRNAs expressed by a doxycycline-responsive promoter downstream of the Collagen A1 locus allowing an inducible and dose-dependent regulation of shRNA. As we have previously reported, the induction of RPS19 deficiency results in a reduction in the number of erythrocytes, platelets and white blood cells, and flow cytometric analysis of bone marrow after a short-term induction reveals increased frequencies of hematopoietic stem and progenitor cells reflecting the onset of stress hematopoiesis. In the current study we have analyzed the long-term effect of RPS19 deficiency in bone marrow. In contrast to a short-term induction, flow cytometric analysis of bone marrow after 51 days revealed decreased frequencies of hematopoietic stem and progenitor cells that correlate with a severe peripheral blood phenotype. In addition, we observed a 3–6 fold increase in apoptosis in RPS19-deficient bone marrow compared to controls based on TUNEL assay. Furthermore, transplantation of whole bone marrow cells from transgenic donors into wild type lethally irradiated recipients confirms that the observed phenotype is autonomous to the blood system. To study whether long-term RPS19 deficiency functionally impairs hematopoietic stem cells, we pre-induced mice for 30 days followed by 15 days without doxycycline to restore the RPS19 expression. Mice were sacrificed and total bone marrow cells were transplanted together with wild-type competitor cells (1:1) into wild type lethally irradiated recipients without doxycycline. This experimental setting allows us to assess the functionality of pre-induced hematopoietic stem cells in absence of ribosomal stress. Flow cytometric analysis of peripheral blood one month after transplantation clearly demonstrates decreased reconstitution from pre-induced donors compared to the wild-type competitor. While this time point reflects mainly the function of transplanted progenitors, long-term analysis of hematopoietic stem cell function in these recipients is ongoing. To study the molecular mechanisms underlying the hematopoietic defect we performed comparative microarray analysis. We chose to analyze preCFU-E/CFU-E erythroid progenitors since we have previously located the erythroid defect at the CFU-E – proerythroblast transition based on flow cytometry and clonogenic proliferation cultures of prospectively isolated erythroid progenitors. Microarray analysis of preCFU-E/CFU-E progenitors reveals deregulation of several genetic pathways, including a robust upregulation of p53 pathway genes, and these targets have been confirmed by real-time PCR. Furthermore, many of p53 target genes are also upregulated in the Lineage− Sca-1+ c-Kit+ (LSK) population that contains immature hematopoietic progenitors and stem cells suggesting that the activation of p53 is not restricted to the erythroid lineage. To ask whether increased activity of p53 can solely explain the hematopoietic phenotype, we have crossed our mouse model into a p53-null background. In summary, our data suggest that RPS19-deficient mice fail to uphold stress hematopoiesis for extended periods of time, with chronic RPS19 deficiency causing bone marrow failure. Disclosures: No relevant conflicts of interest to declare.

Characteristics of Laboratory Screening Suggest That Paroxysmal Nocturnal Hemoglobinuria (PNH) Is Perceived Primarily as a Bone Marrow Failure Syndrome Rather Than as a Hemolytic Anemia

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 4107-4107
Author(s):  
Hwee Yong Lim ◽  
Marjorie Farley ◽  
Carl Wittwer ◽  
Charles Parker
Keyword(s):  
Bone Marrow ◽  
Flow Cytometry ◽  
Cell Surface ◽  
Peripheral Blood ◽  
Bone Marrow Failure ◽  
Flow Cytometric Analysis ◽  
Small Populations ◽  
Hematopoietic Stem ◽  
Flow Cytometric ◽  
Bone Marrow Failure Syndromes

Abstract PNH is a hematopoietic stem cell disorder in which the predominant clinical manifestations are hemolysis, bone marrow failure and thrombophilia. PNH arises as a result of somatic mutation of PIGA, an X-linked gene required for synthesis of the glycosyl phosphatidylinositol (GPI) moiety that anchors some proteins to the cell surface; and consequently, progeny of affected stem cells are deficient in all GPI-anchored proteins (GPI-APs). The hemolysis of PNH is the result of deficiency of CD55 and CD59, GPI-APs that normally inhibit complement activation on the red cell surface, but the relationship between GPI-AP deficiency and the bone marrow failure and thrombophilia of PNH are enigmatic. The peripheral blood of patients with PNH is a mosaic of normal and abnormal cells, and the degree of mosaicism varies greatly among patients. By using fluorescently labeled antibodies, GPI-AP deficient cells (GPI-AP−) can be distinguished form GPI-AP sufficient cells (GPI-AP+) cells by flow cytometric analysis, allowing quantitation of mosaicism. Flow cytometry has been used diagnostically for more than a decade, and technical modifications have improved resolution so that very small populations of GPI-AP− peripheral blood cells can be accurately detected. The purpose of these studies was to generate insights into how PNH is perceived in the community by analyzing the results of a commercially available screening assay using data from a national clinical diagnostic laboratory (ARUP Laboratories, Salt Lake City, UT). The flow cytometric method used in these studies is a modification of the high-resolution two-color assay of Sugimori and colleagues (Blood2006, 107:1308–1314). Clients are given the choice of testing for PNH by analyzing peripheral blood RBCs or PMNs (or both). The acidified serum test (Ham’s test) and the sucrose lysis test (sugar water test) are also available for screening for PNH. For flow cytometric analysis of RBCs, a value of ≥0.005% GPI-AP− cells is considered abnormal, while for PMNs ≥0.003% is abnormal. From January 1, 2008 to June 30, 2008, 1,113 RBC assays and 133 PMN assays were performed. An abnormally large population of GPI-AP− RBCs was identified in 55 cases (5%). The percentage of GPI-AP− RBC ranged from 0.009–69.603% with a median of 1.405%. Twenty-two cases (40%) had >5% GPI-AP− RBCs, while 18 cases (33%) had >10% GPI-AP− RBCs. Of the 133 PMN assays performed, 15 (11%) were abnormal. The range of GPI-AP− PMNs was 0.004–97.727% with a median of 18.327 %. Eight samples (53%) had >10% GPI-AP− PMNs. During the 1-year period from July 1, 2007-June 30, 2008 the acidified serum lysis test (Ham’s test) was performed on 212 samples while the sucrose lysis test was performed on 148 samples. These studies suggest that screening for PNH is common (~43 RBC assays/week compared to 44 assays/week for flow cytometric screening of peripheral blood for lymphoproliferative disorders and leukemia), but the vast majority of samples tested show normal expression of GPI-APs. That so many of the test samples are negative, and that the median for abnormal RBC samples is ~1.5 % GPI-AP− cells, suggest that most of the screening is done because of the association of PNH with bone marrow failure syndromes rather than because of evidence of intravascular hemolysis. These studies underscore the need to understand the pathophysiological basis and clinical implications of small populations of GPI-AP deficient cells in patients with bone marrow failure syndromes. Nonetheless, 18 cases with >10% GPI-AP− RBCs were detected during the 6 months of observation, indicating that the prevalence of classic PNH in the US is substantial. That PNH clone size is best determined by analysis of GPI-AP expression on PMNs does not appear to be widely appreciated in the community as the PMN assays is requested 12% as often as the RBC assay. Flow cytometry has largely, but not completely, replaced Ham’s test and the sucrose lysis test as screening assays for PNH.

scholarly journals Syngeneic bone marrow transplantation without conditioning in a patient with paroxysmal nocturnal hemoglobinuria: in vivo evidence that the mutant stem cells have a survival advantage

Blood ◽  
1996 ◽  
Vol 88 (2) ◽  
pp. 742-750 ◽  
Author(s):  
M Endo ◽  
PG Beatty ◽  
TM Vreeke ◽  
CT Wittwer ◽  
SP Singh ◽  
...  
Keyword(s):  
Stem Cells ◽  
Bone Marrow ◽  
Paroxysmal Nocturnal Hemoglobinuria ◽  
Pathological Process ◽  
Survival Advantage ◽  
Hematopoietic Stem ◽  
Glycosyl Phosphatidylinositol ◽  
Normal Expression ◽  
Marrow Infusion

A 10-year-old girl with paroxysmal nocturnal hemoglobinuria (PNH) received an infusion of syngeneic bone marrow without preparative marrow ablation or immunosuppression. Following transplant, the patient became asymptomatic in concordance with an increase in the percentage of peripheral blood cells with normal expression of glycosyl phosphatidylinositol-anchored proteins (GPI-AP). However, molecular analysis suggested engraftment of a relatively small number of donor stem cells and persistence of an abnormal stem cell with mutant PIG-A. During 17 months of observation, the percentage of cells with normal GPI-AP expression gradually decreased, while intravascular hemolysis progressively increased. Approximately 16.5 months post-transplant, the patient once again became symptomatic. Together, these results indicate that syngeneic marrow infusion provided a clinical benefit by increasing the proportion of erythrocytes with normal expression of GPI- anchored complement regulatory proteins without supplanting the abnormal stem cells. However, evidence of insidious disease progression following the marrow infusion implies that the abnormal stem cells have a survival advantage relative to the transplanted stem cells. Thus, these studies contribute in vivo data in support of the hypothesis that PNH arises as a consequence of a pathological process that selects for hematopoietic stem cells that are GPI-AP-deficient.

Characteristics of De Novo Acute Leukemia Patients with Glycosylphosphatidylinositol (GPI) Protein-Negative Population of Leukemic Cells.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 4462-4462
Author(s):  
Hideyoshi Noji ◽  
Tsutomu Shichishima ◽  
Masatoshi Okamoto ◽  
Kazuhiko Ikeda ◽  
Akiko Nakamura ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Acute Leukemia ◽  
De Novo ◽  
Bone Marrow Failure ◽  
Flow Cytometric Analysis ◽  
Leukemic Cells ◽  
Remission Induction ◽  
Color Flow ◽  
Flow Cytometric ◽  
Number Of Patients

Abstract Paroxysmal nocturnal hemoglobinuria (PNH) is considered to be an acquired stem cell disorder affecting all hematopoietic lineages, which lack GPI-anchored membrane proteins, such as CD59, because of abnormalities in the phosphatidylinositol glycan-class A (PIG-A) gene. Also, PNH is one disorder of bone marrow failure syndromes, including aplastic anemia and myelodysplastic syndrome, which are considered as pre-leukemic states. In this study, to know some characteristics of patients with de novo acute leukemia, we investigated expression of CD59 in leukemic cells from 25 patients (female: male=8: 17; mean age ± standard deviation, 57.8 ± 19.5 years) with de novo acute leukemia by single-color flow cytometric analysis. In addition, the PIG-A gene from CD59− leukemic cells sorted by FACS Vantage in 3 patients with acute leukemia was examined by sequence analysis. All the patients had no past history of PNH. Based on the French-American-British criteria, the diagnosis and subtypes of acute leukemia were determined. The number of patients with subtypes M1, M2, M3, M4, M5, and M7 was 1, 14, 2, 4, 2, and 2, respectively. Two of the patients were classified into acute myeloid leukemia with trilineage myelodysplasia from morphological findings in bone marrow. Chromosomal analyses presented abnormal karyotypes in 14 of 25 patients. Flow cytometric analyses showed that leukemic cells from 16 of 25 patients (64%) had negative populations of CD59 expression and the proportion of the populations was 63.3 ± 25.7%, suggesting the possibility that CD59− leukemic cells from patients with de novo acute leukemia might be derived from PNH clones. In fact, the PIG-A gene analyses showed that monoclonal or oligoclonal PIG-A mutations in coding region were found in leukemic cells from 3 patients with CD59− leukemic cells and all of the clones with the PIG-A mutations were minor. Then, various clinical parameters, including rate of complete remission for remission-induction chemotherapy, peripheral blood, bone marrow blood, and laboratory findings, and results of chromosomal analyses were statistically compared between 2 groups of patients with (n=16) and without (n=9) CD59− leukemic cells. The reticulocyte counts (10.5 ± 13.0 x 104/μl) and proportions of bone marrow erythroblasts (17.5 ± 13.9%) in patients with only CD59+ leukemic cells were significantly higher than those (2.5 ± 1.7 x 104/μl, p<0.05; and 5.6 ± 6.2%, p<0.01, respectively) in patients with CD59− leukemic cells. The proportions of bone marrow blasts (69.3 ± 21.1%) in patients with CD59− leukemic cells were significantly higher than those (45.5 ± 19.3%, p<0.02) in patients with only CD59+ leukemic cells. In conclusion, our findings indicate that leukemic cells derived from PNH clones may be common in de novo acute leukemia patients, suggesting that bone marrow failure may have already occurred in localized bone marrow even in de novo acute leukemia.

Prostaglandin E2 (PGE2) Treatment Rapidly Increases the Fraction of Non-Dividing Hematopoietic Stem Cells (HSCs)

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 73-73
Author(s):  
Rebecca L Porter ◽  
Benjamin J Frisch ◽  
Regis J O’Keefe ◽  
Laura M Calvi
Keyword(s):  
Cell Cycle ◽  
Bone Marrow ◽  
Prostaglandin E2 ◽  
Flow Cytometric Analysis ◽  
Brdu Incorporation ◽  
Hematopoietic Stem ◽  
Hematopoietic System ◽  
Cell Fate Decisions ◽  
Flow Cytometric ◽  
Incorporated Brdu

Abstract HSCs are pluripotent cells responsible for the establishment and renewal of the entire hematopoietic system. Our group and others have established that osteoblastic cells in the bone marrow microenvironment regulate HSC cell fate decisions. Specifically, Parathyroid hormone (PTH) expands HSCs by activating osteoblasts in the HSC niche. However, the molecular mechanisms for this increase are unknown. PTH increases local production of prostaglandin E2 (PGE2) in osteoblasts by stimulating cyclo-oxygenase 2 (Cox-2). We also recently found that treatment of osteoblastic MC3T3 cells with PTH (10−7 M) rapidly induces PGE2 Synthase expression. Therefore, we hypothesized that PGE2 may act as a mediator of the PTH effect on HSCs. We have shown that in vivo PGE2 treatment caused a 2.75-fold increase in lineage− Sca-1+ c-kit+ (LSK) cells within the bone marrow compared with vehicle treated mice (p=0.0061, n=8/group). Bone marrow mononuclear cells (BMMC) from mice treated with PGE2 also demonstrated superior lymphomyeloid reconstitution in competitive repopulation analyses, suggesting that HSCs are being expanded or modulated to more efficiently reconstitute the hematopoietic system in the recipients. It is known that HSCs that reside in the G0 phase of the cell cycle have increased ability to reconstitute myeloablated recipient mice. Since PGE2 treatment resulted in superior reconstitution, we hypothesized that PGE2 may increase the percentage of HSCs residing in G0. To test this hypothesis, we treated BMMC from male C57b/6 mice with 10−6 M PGE2 or vehicle for 90 minutes. The percentage of cells in G0 vs. G1 was determined by flow-cytometric analysis using the RNA and DNA dyes, Pyronin-Y and Hoechst 33342 respectively. As we predicted, PGE2 treatment increased the percentage of wild-type LSK cells in G0 1.85 fold over vehicle-treated LSK cells (23.63% in vehicle-treated, n=4 vs. 43.7% in PGE2-treated, n=6). Since the PTH-dependent increase in HSCs is Protein Kinase A (PKA) mediated and the PGE2 receptors EP2 and EP4 signal via PKA, we assayed the effect of PGE2 on the percentage of cells in G0 in mice lacking the EP2 receptor (EP2−/− mice). Interestingly, there was no enrichment for HSC in G0 when BMMC from EP2−/− mice were treated with PGE2 (55.25% in vehicle-treated, n=4 vs. 56.06% in PGE2-treated, n=5). These findings suggest that PGE2-dependent regulation of HSC activity may involve increasing the percentage of HSCs that reside in G0 by activation of EP2, thereby augmenting their ability to reconstitute the hematopoietic system of a myeloablated recipient. 5-bromo-2-deoxyuridine (BrdU) incorporation was also used to investigate the effect of PGE2 on cell cycling of HSCs. Male 6–8 week old C57b/6 mice were injected intraperitoneally with 1 mg BrdU and PGE2 (6 mg/kg) or vehicle. After 30, 60, 90 or 120 minutes, mice were sacrificed and BMMC were subjected to flow cytometric analysis for incorporation of BrdU and DNA content in HSCs. As expected for the highly quiescent HSC population, only a small fraction of HSCs incorporated BrdU. After 30 and 60 minutes of treatment, there was no difference in the percentage of cells that incorporated BrdU between vehicle and PGE2-treated mice. However, at the 90 and 120 minute time points, there were significantly less HSCs cycling in the bone marrow from the PGE2 treated mice (12.1% vs. 5.3% at 90 min, n=2 per group; 11.1% vs. 1.8% at 120 min, n=5 per group, p=0.0060), suggesting that fewer PGE2-treated cells were synthesizing DNA. Taken together, the increase in the percentage of HSCs in G0 and the decrease in cycling HSCs after PGE2 treatment indicate that PGE2 could improve engraftment and reconstitution of the hematopoietic system by enriching for HSCs in G0. These results suggest that PGE2 may exert its beneficial effect on bone marrow reconstitution by altering cell cycle dynamics in HSCs. Identification of the molecular events mediating this novel PGE2 action on HSC could provide additional targets for HSC manipulation in clinical situations requiring rapid and efficient bone marrow reconstitution, such as recovery from iatrogenic or pathologic myeloablative injury.

Bone Marrow Histology in Patients with Paroxysmal Nocturnal Hemoglobinuria.

Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. 4215-4215
Author(s):  
Sandra van Bijnen ◽  
Konnie Hebeda ◽  
Petra Muus
Keyword(s):  
Bone Marrow ◽  
Mast Cells ◽  
Aplastic Anemia ◽  
Paroxysmal Nocturnal Hemoglobinuria ◽  
Plasma Cells ◽  
Bone Marrow Failure ◽  
Clone Size ◽  
Immune Mediated ◽  
Lymphoid Nodules ◽  
Pnh Clone

Abstract Abstract 4215 Introduction Paroxysmal Nocturnal Hemoglobinuria (PNH) is a disease of the hematopoietic stem cell (HSC) resulting in a clone of hematopoietic cells deficient in glycosyl phosphatidyl inositol anchored proteins. The clinical spectrum of PNH is highly variable with classical hemolytic PNH at one end, and PNH in association with aplastic anemia (AA/PNH) or other bone marrow failure states at the other end. It is still largely unknown what is causing these highly variable clinical presentations. Immune-mediated marrow failure has been suggested to contribute to the development of a PNH clone by selective damage to normal HSC. However, in classic PNH patients with no or only mild cytopenias, a role for immune mediated marrow failure is less obvious. No series of trephine biopsies has been previously documented of patients with PNH and AA/PNH to investigate the similarities and differences in these patients. Methods We have reviewed a series of trephine biopsies of 41 PNH patients at the time the PNH clone was first detected. The histology was compared of 27 patients with aplastic anemia and a PNH clone was compared to that of 14 patients with classic PNH. Age related cellularity, the ratio between myeloid and erythroid cells (ME ratio), and the presence of inflammatory cells (mast cells, lymphoid nodules and plasma cells) were evaluated. The relation with clinical and other laboratory parameters of PNH was established. Results Classic PNH patients showed a normal or hypercellular marrow in 79% of patients, whereas all AA/PNH patients showed a hypocellular marrow. Interestingly, a decreased myelopoiesis was observed not only in AA/PNH patients but also in 93% of classic PNH patients, despite normal absolute neutrophil counts (ANC ≥ 1,5 × 109/l) in 79% of these patients. The number of megakaryocytes was decreased in 29% of classic PNH patients although thrombocytopenia (< 150 × 109/l) was only present in 14% of the patients. Median PNH granulocyte clone size was 70% (range 8-95%) in classic PNH patients, whereas in AA/PNH patients this was only 10% (range 0.5-90%). PNH clones below 5% were exclusively detected in the AA/PNH group. Clinical or laboratory evidence of hemolysis was present in all classical PNH patients and in 52% of AA/PNH patients and correlated with PNH granulocyte clone size. Bone marrow iron stores were decreased in 71% of classic PNH patients. In contrast, increased iron stores were present in 63% of AA/PNH patients, probably reflecting their transfusion history. AA/PNH patients showed increased plasma cells in 15% of patients and lymphoid nodules in 37%, versus 0% and 11% in classic PNH. Increased mast cells (>2/high power field) were three times more frequent in AA/PNH (67%) than in PNH (21%). Conclusion Classic PNH patients were characterized by a more cellular bone marrow, increased erythropoiesis, larger PNH clones and clinically by less pronounced or absent peripheral cytopenias and more overt hemolysis. Decreased myelopoiesis and/or megakaryopoiesis was observed in both AA/PNH and classic PNH patients, even in the presence of normal peripheral blood counts, suggesting a role for bone marrow failure in classic PNH as well. More prominent inflammatory infiltrates were observed in AA/PNH patients compared to classical PNH patients. Disclosures: No relevant conflicts of interest to declare.

Screening Patients with Myelodysplastic Syndrome and Aplastic Anemia for Paroxysmal Nocturnal Hemoglobinuria Clones: A Retrospective Study,

Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 3426-3426 ◽  
Author(s):  
Andrew Shih ◽  
Ian H. Chin-Yee ◽  
Ben Hedley ◽  
Mike Keeney ◽  
Richard A. Wells ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Retrospective Study ◽  
Aplastic Anemia ◽  
Board Of Directors ◽  
Paroxysmal Nocturnal Hemoglobinuria ◽  
Bone Marrow Failure ◽  
Cell Surface Expression ◽  
Advisory Committees ◽  
Hematopoietic Stem ◽  
Pnh Clone

Abstract Abstract 3426 Introduction: Paroxysmal Nocturnal Hemoglobinuria (PNH) is a rare disorder due to a somatic mutation in the hematopoietic stem cell. The introduction of highly sensitive flow cytometric and aerolysin testing have shown the presence of PNH clones in patients with a variety of other hematological disorders such as aplastic anemia (AA) and myelodysplasic syndrome (MDS). It is hypothesized that patients with these disorders and PNH clones may share an immunologic basis for marrow failure with relative protection of the PNH clone, due to their lack of cell surface expression of immune accessory proteins. This is supported by the literature showing responsiveness in AA and MDS to immunosuppressive treatments. Preliminary results from a recent multicenter trial, EXPLORE, notes that PNH clones can be seen in 70% of AA and 55% of MDS patients, and therefore there may be utility in the general screening of all patients with bone marrow failure (BMF) syndromes. Furthermore, it has been suggested that the presence of PNH cells in MDS is a predictive biomarker that is clinically important for response to immunosuppressive therapy. Methods: Our retrospective cohort study in a tertiary care center used a high sensitivity RBC and FLAER assay to detect PNH clones as small as 0.01%. Of all patients screened with this method, those with bone marrow biopsy and aspirate proven MDS, AA, or other BMF syndromes (defined as unexplained cytopenias) were analysed. Results from PNH assays were compared to other clinical and laboratory parameters such as LDH. Results: Overall, 102 patients were initially screened over a 12 month period at our center. 30 patients were excluded as they did not have biopsy or aspirate proven MDS, AA, or other BMF syndromes. Of the remaining 72 patients, four patients were found to have PNH clones, where 2/51 had MDS (both RCMD, IPSS 0) [3.92%] and 2/4 had AA [50%]. The PNH clone sizes of these four patients were 0.01%, 0.01%, 0.02%, and 1.7%. None of the MDS patients with known recurrent karyotypic abnormalities had PNH clones present. Only one of the four patients had a markedly increased serum LDH level. Conclusions: Our retrospective study indicates much lower incidence of PNH clones in MDS patients or any patients with BMF syndromes when compared to the preliminary data from the EXPLORE trial. There is also significant disagreement in other smaller cohorts in regards to the incidence of PNH in AA and MDS. Screening for PNH clones in patients with bone marrow failure needs further study before adoption of widespread use. Disclosures: Keeney: Alexion Pharmaceuticals Canada Inc.: Consultancy, Membership on an entity's Board of Directors or advisory committees. Wells:Alexion Pharmaceuticals Canada Inc: Honoraria. Sutherland:Alexion Pharmaceuticals Canada Inc.: Consultancy, Membership on an entity's Board of Directors or advisory committees.

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