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Historically, a principal reason Western medicine has progressed to the degree it has is the epistemology used to define disease. Diseases are distinguished by two main methods: (1) assembly of defining characteristics (symptoms, physical descriptions both direct and derived from imaging techniques, and laboratory findings and clinical course) that recur so as to form a clinical template and (2) assessment of cause and effects of the clinically defined disease. The method was first clearly established in the nineteenth century with the definition of microbial diseases and received its second great impetus with the development of molecular genetics. Although the pattern has been altered in more recent times with the development of science leading to the definition of disease, a study of the classical methodology has a clear place in the study of disease.

Eculizumab reduces intravascular haemolysis and improves disease symptoms in patients with paroxysmal nocturnal haemoglobinuria (PNH).To characterise, in a real-world setting, the effect of eculizumab in patients with haemolytic PNH (lactase dehydrogenase (LDH) ≥ 1.5 upper limit of normal) and no history of red blood cell transfusion, including those with high disease activity (HDA).Three populations from the International PNH Registry were studied: (i) non-transfused, untreated; (ii) non-transfused, eculizumab-treated and (iii) transfused, eculizumab-treated (≥1 transfusions in 6 months prior to eculizumab initiation). Using multivariate linear regression, the primary outcome was mean absolute change from baseline to 6 months in LDH (U/L) in non-transfused patients who were treated with eculizumab versus those who remained untreated. Secondary outcomes were mean changes in functional assessment of chronic illness therapy (FACIT)-Fatigue and European Organisation for Research and Treatment of Cancer Quality of Life Questionnaire (EORTC-QLQ)-C30 Fatigue scores from baseline to last available assessment.The study population included (i) 144 non-transfused, untreated patients; (ii) 45 non-transfused, eculizumab-treated patients and (iii) 105 transfused, eculizumab-treated patients. Of these, 136/144, 43/45 and 99/105 had HDA respectively. Compared with untreated patients, non-transfused, treated patients had greater absolute reduction in LDH (-1318.8 vs -39.4; P 0.001) and greater percentage reduction in LDH (-69.9 vs -1.6%; P 0.001). Clinically meaningful improvements in FACIT-Fatigue (73.7 vs 24.6%, respectively) and in EORTC-QLQ-C30 (84.2 vs 33.3%, respectively) were observed. Non-transfused, treated patients with HDA had significantly reduced LDH levels (P 0.001) and clinically meaningful improvements in FACIT-Fatigue (P = 0.003) and EORTC-QLQ-C30 (P = 0.020) versus untreated patients.Significant LDH reduction and clinically meaningful improvement in fatigue were observed in patients with PNH and HDA treated with eculizumab versus untreated patients, irrespective of transfusion history.

Paroxysmal nocturnal hemoglobinuria (PNH) is a debilitating and life-threatening disease in which lysis of PNH red blood cells frequently manifests with chronic hemolysis, anemia, and thrombosis. Renal damage in PNH is associated with chronic hemosiderosis and/or microvascular thrombosis. We determined the incidence of renal dysfunction or damage, defined by stages of chronic kidney disease (CKD), in a large cohort of PNH patients and evaluated the safety and efficacy of the complement inhibitor eculizumab in altering its progression. Renal dysfunction or damage was observed in 65% of the study population at baseline with 21% of patients with later stage CKD or kidney failure (glomerular filtration rate [GFR] ≤60 ml/min/1.73 m2; Stage 3, 4, or 5). Eculizumab treatment was safe and well-tolerated in patients with renal dysfunction or damage and resulted in the likelihood of improvement as defined as categorical reduction in CKD stage (P < 0.001) compared with baseline and to placebo (P = 0.04). Improvement in renal function was more commonly seen in patients with baseline CKD Stages 1–2 (67.1% improvement, P < 0.001) although improvement was also observed in patients with CKD Stages 3–4 (P = 0.05). Improvements occurred quickly and were sustained for at least 18 months of treatment. Patients categorized at CKD Stages 3–5 did not worsen during treatment with eculizumab. Overall, 40 (21%) of 195 patients who demonstrated renal dysfunction or damage at baseline were no longer classified as such after 18 months of treatment. Administration of eculizumab to patients with renal dysfunction or damage was well tolerated and was usually associated with clinical improvement. Am. J. Hematol. 85:553–559, 2010. © 2010 Wiley-Liss, Inc.

The primary clinical manifestations of paroxysmal nocturnal hemoglobinuria (PNH) are hemolytic anemia, marrow failure, and thrombophilia. However, PNH is not a simple binary diagnosis and both flow cytometric characterization of glycosyl phosphatidylinositol–anchored protein expression on peripheral blood cells and marrow analysis are required for comprehensive disease classification. For optimum management, the contribution of both hemolysis and marrow failure to the complex anemia of PNH should be determined. Complement inhibition by eculizumab is a promising new approach to treating the hemolytic anemia. Stem cell transplantation is potentially curative, but the decision on use is best made on a case-by-case basis because of the heterogeneous natural history of the disease. PNH clone size and ethnic/geographic factors appear to influence thrombophilic propensity, but a consensus on prophylactic anticoagulation has not been reached. Involvement of unusual sites (hepatic, mesenteric, cerebral, dermal veins) is characteristic of the thrombophilia of PNH. Indefinite anticoagulation is recommended following a thromboembolic event and thrombolytic therapy should be considered for acute hepatic vein thrombosis (Budd-Chiari syndrome). Pregnancy in a patient with PNH is complicated and requires careful management including prophylactic anticoagulation. To obtain a broad overview of the natural history, approaches to management, and outcome, the International PNH Registry was recently established.

ABSTRACT Although paroxysmal nocturnal hemoglobinuria (PNH) is often associated with aplastic anemia (AA), the nature of the pathogenetic link between PNH and AA remains unclear. Moreover, the PIG-A mutation appears to be necessary but not sufficient for the development of PNH, suggesting other factors are involved. The ability of PNH marrow cells to form in vitro hematopoietic colonies and the ability of PNH marrow to generate stroma that could support hematopoiesis of normal or PNH marrow in cross culture were investigated. PNH marrow from both post-Ficoll and post-lineage depleted hematopoietic progenitor cells grew similarly significantly fewer colonies than normal marrow. Sorting of CD59 + and CD59 − CD34 + CD38 − cells from patients with PNH showed similarly impaired clonogenic efficiency, indicating that the hematopoietic defect in PNH does not directly relate to GPI-anchored protein expression. PNH marrow readily grew stroma similar to marrow from normal donors. Cross culture experiments revealed that PNH stroma appears to function normally in vitro; it can support growth of normal marrow cells as well as normal stroma does, but neither PNH nor normal stroma could support the growth of PNH marrow cells. The hematopoietic defect in PNH is not due to defective stroma, but is due to defective progenitor cell growth related to additional unknown factors.

Contains fulltext : 136926.pdf (Publisher’s version ) (Open Access) Paroxysmal nocturnal hemoglobinuria is a rare, acquired disease associated with hemolytic anemia, bone marrow failure, thrombosis, and, frequently, poor quality of life. The International PNH Registry is a worldwide, observational, non-interventional study collecting safety, effectiveness, and quality-of-life data from patients with a confirmed paroxysmal nocturnal hemoglobinuria diagnosis or detectable paroxysmal nocturnal hemoglobinuria clone, irrespective of treatment. In addition to evaluating the long-term safety and effectiveness of eculizumab in a global population, the registry aims to improve diagnosis, optimize patient management and outcomes, and enhance the understanding of the natural history of paroxysmal nocturnal hemoglobinuria. Here we report the characteristics of the first 1610 patients enrolled. Median disease duration was 4.6 years. Median granulocyte paroxysmal nocturnal hemoglobinuria clone size was 68.1% (range 0.01-100%). Overall, 16% of patients had a history of thrombotic events and 14% a history of impaired renal function. Therapies included anticoagulation (31%), immunosuppression (19%), and eculizumab (25%). Frequently reported symptoms included fatigue (80%), dyspnea (64%), hemoglobinuria (62%), abdominal pain (44%), and chest pain (33%). Patients suffered from poor quality of life; 23% of patients had been hospitalized due to paroxysmal nocturnal hemoglobinuria-related complications and 17% stated that paroxysmal nocturnal hemoglobinuria was the reason they were not working or were working less. This international registry will provide an ongoing, valuable resource to further the clinical understanding of paroxysmal nocturnal hemoglobinuria.

Paroxysmal nocturnal hemoglobinuria (PNH) is a clonal hematopoietic stem cell disorder characterized by complement-mediated hemolysis due to deficiencies of glycosylphosphatidylinositol-anchored proteins (GPI-APs) in subpopulations of blood cells. Acquired mutations in the X-linked phosphatidylinositol glycan–class A (PIG-A) gene appear to be the characteristic and pathogenetic cause of PNH. To develop a gene therapy approach for PNH, a retroviral vector construct, termed MPIN, was made containing the PIG-A complementary DNA along with an internal ribosome entry site and the nerve growth factor receptor (NGFR) as a selectable marker. MPIN transduction led to efficient and stable PIG-A and NGFR gene expression in a PIG-A–deficient B-cell line (JY5), a PIG-A–deficient K562 cell line, an Epstein-Barr virus–transformed B-cell line (TK-14−) established from a patient with PNH, as well as peripheral blood (PB) mononuclear cells from a patient with PNH. PIG-A expression in these cell lines stably restored GPI-AP expression. MPIN was transduced into bone marrow mononuclear cells from a patient with PNH, and myeloid/erythroid colonies and erythroid cells were derived. These transduced erythroid cells restored surface expression of GPI-APs and resistance to hemolysis. These results indicate that MPIN is capable of efficient and stable functional restoration of GPI-APs in a variety of PIG-A–deficient hematopoietic cell types. Furthermore, MPIN also transduced into PB CD34+ cells from a normal donor, indicating that MPIN can transduce primitive human progenitors. These findings set the stage for determining whether MPIN can restore PIG-A function in multipotential stem cells, thereby providing a potential new therapeutic option in PNH.

The characteristic, defining defect in paroxysmal nocturnal hemoglobinuria is the somatic mutation of the PIG-A gene (essential to the biosynthesis of the glycosylphosphatidylinositol moiety that affixes a number of proteins to the cellular surface) in hematopoietic cells. These cells thus lack the proteins usually held in place by this anchor. The absence of these proteins is the most reliable diagnostic criterion of the disease and is responsible for many of the clinical manifestations of PNH. The current hypothesis explaining the disorder suggests that there are two components: (1) hematopoietic stem cells with the characteristic defect are present in the marrow of many if not all normal individuals in very small numbers; (2) some aplastogenic influence suppresses the normal stem cells but does not suppress the defective stem cells, thus allowing the proportion of these cells to increase. Current research attempts to substantiate this hypothesis and design therapy consistent with the hypothesis. Paroxysmal nocturnal hemoglobinuria (PNH) is an acquired stem cell disorder characterized by intravascular hemolysis, hypercoagulability, and relative bone marrow failure [1]. It is characterized by a somatic mutation in the gene encoding the alpha1-6-N-acetylglucosaminyltransferase necessary for the formation of the glycosylphosphatidylinositol (GPI) anchor that binds certain proteins to the membrane surface (Fig. 1) [2,3*]. Whereas many of the manifestations can be accounted for by the absence of these proteins on the cells of the hematopoietic system, it is not entirely clear whether this defect is sufficient to make the disease manifest. In this paper, the author reviews recent clinical observations and relates them to the underlying pathophysiology of the disease.

Thrombosis may be important in the pathophysiology of certain complications of sickle cell anemia (SCA), including cerebrovascular accident (CVA, stroke) and avascular necrosis (AVN). No single laboratory or clinical parameter can accurately identify patients who will develop these thrombotic complications. We hypothesized that a subset of patients with SCA have genetic thrombophilic mutations that increase the risk of stroke or AVN. We examined nine known thrombophilic DNA polymorphisms in α-fibrinogen, β-fibrinogen, platelet glycoprotein IIIa, Factor VII, methylenetetra-hydrofolate reductase, plasminogen activator inhibitor-1, prothrombin, and Factor V genes in 101 African-American patients with SCA (27 CVA, 16 AVN). The allele frequency of thrombophilic mutations ranged from 0.0 (Prothrombin, Factor V) to 0.33 (α-fibrinogen). No mutation was significantly more common in patients with CVA or AVN than in patients without these complications. These nine thrombophilic mutations do not appear to be significant risk factors for the development of clinically overt CVA or AVN in SCA.

Hydroxyurea (HU) is an effective therapeutic agent for patients with myeloproliferative disorders (MPDs) or sickle cell disease (SCD). Short-term HU toxicities primarily include transient myelosuppression, but long-term HU risks have not been defined. The mutagenic and carcinogenic potential of HU is not established, although HU has been associated with an increased risk of leukemia in some patients with MPD. In this study, 2 assays were used to quantitate acquired somatic DNA mutations in peripheral blood mononuclear cells (PBMCs) after in vivo HU exposure. The HPRT assay measures hypoxanthine phosphoribosyl transferase (hprt) mutations, while the VDJ assay identifies “illegitimate” T-cell receptor Vγ-Jβ interlocus recombination events. PBMCs were analyzed from patients with MPD, adults and children with SCD, and normal controls. MPD patients with prolonged HU exposure had numbers of DNA mutations equivalent to patients with low HU exposure or controls. Similarly, adults with SCD had equivalent numbers of DNA mutations regardless of HU exposure. Children with SCD and 30-month HU exposure had equivalenthprt− mutations but significantly more VDJ mutations (1.82 ± 1.20 events per μg DNA) than children with 7-month HU exposure (1.58 ± 0.87 events) or no HU exposure (1.06 ± 0.45 events), P = .04 by analysis of variance. Taken together, these data suggest that the mutagenic and carcinogenic potential of in vivo HU therapy is low. Although increased numbers of illegitimate VDJ recombination events do not directly portend leukemia, young patients with SCD and HU exposure should be monitored serially for increases in DNA mutations.

The Multicenter Study of Hydroxyurea in Sickle Cell Anemia (MSH) demonstrated the efficacy of hydroxyurea in reducing the rate of painful crises compared to placebo. We used resource utilization data collected in the MSH to determine the cost-effectiveness of hydroxyurea. The MSH was a randomized, placebo-controlled double-blind clinical trial involving 299 patients at 21 sites. The primary outcome, visit to a medical facility, was one of the criteria to define occurrence of painful crisis. Cost estimates were applied to all outpatient and emergency department visits and inpatient hospital stays that were classified as a crisis. Other resources for which cost estimates were applied included hospitalization for chest syndrome, analgesics received, hydroxyurea dosing, laboratory testing, and clinic visits for management of patient care. Annualized differential costs were calculated between hydroxyurea- and placebo-receiving patients. Hospitalization for painful crisis accounted for the majority of costs in both arms of the study, with an annual mean of $12,160 (95% CI: $9,440, $14,880) for hydroxyurea and $17,290 (95% CI: $13,010, $21,570) for placebo. The difference in means was $5,130 (95% CI: $60, $10,200; P = 0.048). Chest syndrome was the next largest cost with a mean difference of $830 (95% CI: $−340, $2,000; P = 0.16). The hydroxyurea arm was also associated with lower costs for emergency department visits, transfusion, and use of opiate analgesics. In total, the annual average cost per patient receiving hydroxyurea was $16,810 (95% CI: $13,350, $20,270) and the annual average costs per patient receiving placebo was $22,020 (95% CI: $17,340, $26,710). The difference in means was $5,210 (95% CI: $−610, $11,030; P = 0.21). The cost of hydroxyurea with the more intensive monitoring required when using this drug appears to be more than offset by decreased costs for medical care of painful crisis and analgesic use. Although the total cost difference was not significant statistically, these results suggest that hydroxyurea therapy is cost-effective compared to placebo in the management of adult patients with sickle cell anemia. If hydroxyurea can prevent development of chronic organ damage, long-term savings may be even greater. Am. J. Hematol. 64:26–31, 2000. © 2000 Wiley-Liss, Inc.

This review addresses several areas of concern in the care of patients with sickle cell disease. In Sections I and II, the fundamental pathogenetic mechanisms of sickle cell disease and their clinical consequences are discussed. Dr. Narla presents the evidence for abnormal cell adhesiveness by SS cells and Dr. Rosse examines the role of the increased whole blood viscosity. In Section III, Dr. Petz reviews common and uncommon alloimmune consequences of transfusion in sickle cell disease and discusses the diagnosis and management of sickle cell patients with hyperhemolysis after transfusion. In Section IV, Dr. Steinberg gives an update on the use of hydroxyurea in the treatment of sickle cell disease, including the SC and S-β thalassemia variants.

Hemoglobin S/O(Arab) (Hb S/O(Arab)) is a rare compound heterozygous hemoglobinopathy characterized by the presence of two variant beta-globin chains: beta6Glu --> Val (Hb S) and beta121Glu --> Lys (Hb O(Arab)). The diagnosis of Hb S/O(Arab) requires electrophoresis on both cellulose acetate and citrate agar, since Hb O(Arab) co-migrates with Hb C at alkaline pH and close to Hb S at acidic pH. To date only case reports and small series of patients with Hb S/O(Arab) have been described. To better characterize the clinical and laboratory aspects of this unusual disorder, we reviewed the Duke University Medical Center experience. We identified 13 African-American children and adults with Hb S/O(Arab) ranging in age from 2.7 to 62.5 years. All patients had hemolytic anemia with a median Hb of 8.7 gm/dL (range 6.1-9.9 gm/dL), and a median reticulocyte count of 5.8% (range 1.2-10.3%). The peripheral blood smear typically showed sickled erythrocytes, target cells, polychromasia, and nucleated red blood cells. All 13 patients have had significant clinical sickling events including acute chest syndrome (11), recurrent vasoocclusive painful events (10), dactylitis (7), gallstones (5), nephropathy (4), aplastic crises (2), avascular necrosis (2), leg ulcers (2), cerebrovascular accident (CVA) (1), osteomyelitis (1), and retinopathy (1). Four patients have died, including two from pneumococcal sepsis/meningitis at ages 5 and 10 years, one of acute chest syndrome at age 14 years, and one of multiorgan failure at age 35 years. We conclude that Hb S/O(Arab) disease is a severe sickling hemoglobinopathy with laboratory and clinical manifestations similar to those of homozygous sickle cell anemia.

ABSTRACT: Paroxysmal nocturnal hemoglobinuria (PNH) is a hematologic disorder characterized by acquired PIG-A gene mutations that lead to defective bioassembly of glycosylphosphatidylinositol (GPI) anchors and the absence of GPI-linked surface proteins. As the etiology of these acquired PIG-A gene mutations is unknown, we hypothesized that patients with PNH have overall genetic instability and acquire somatic mutations throughout their genome. We first analyzed microsatellite sequences and found equivalent size variation using DNA from GPI-negative granulocytes compared with the DNA of paired GPI-positive B cell lines or normal granulocytes. We next quantitated the frequency of mutations at the hypoxanthine-guanine phosphoribosyl transferase ( hprt ) gene locus, and found 1 PNH patient with a large increase in hprt - mutant frequency (256.7 x 10 -6 vs. 27.8 ± 19.9 x 10 -6 for normal adults) that was confirmed on 4 independent blood samples. We also quantitated “illegitimate” VDJ genetic recombination events between the T cell receptor Vγ and J β gene loci, and found a second PNH patient with a large increase (43.5 events per μg of DNA vs. 1.3 ± 0.8 events per μg of DNA for normal adults), confirmed on 4 independent DNA samples. Both of these PNH patients are young females with no history of aplastic anemia. Our data show that PNH patients can have increased numbers of acquired somatic mutations in gene loci distinct from PIG-A. These data suggest that genetic instability may be associated with the development of PIG-A mutations that lead to the clinical picture of PNH.

Secreted IgM is predominantly found as pentameric molecules, but IgM can also be secreted as hexamers by B cell lines. Murine hexamers activate the complement cascade more efficiently than pentamers, but the physiologic significance of hexameric IgM remains unknown. Here, we report that IgM hexamers and pentamers are cleared from the circulation with similar kinetics, suggesting that the predominance of pentameric IgM in vivo reflects the regulation of polymer assembly and secretion in responding B cells. Normal IgM-secreting B cells, particularly those from the peritoneal cavity, are capable of secreting abundant hexameric IgM in vitro. The disparity between the ability of B cells to secrete IgM hexamers in vitro and the paucity of this polymer in vivo suggest that IgM hexamers might be deleterious. In support of this, we demonstrate that the autoantibodies from a number of patients with cold agglutinin (CA) disease include both IgM hexamers and pentamers. The CA IgM hexamers lyse human erythrocytes in the presence of human complement more efficiently than CA IgM pentamers, suggesting a potential role for hexameric IgM in the pathogenesis of this autoimmune syndrome.

Paroxysmal nocturnal hemoglobinuria (PNH) is a clonal stem cell disorder characterized by complement-mediated hemolysis and deficient hematopoiesis. The development of PNH involves an acquired mutation in the X-linked PIG-A gene, which leads to incomplete bioassembly of glycosylphosphatidylinositol (GPI) anchors and absent or reduced surface expression of GPI-linked proteins. The origin and mechanisms by which the PNH clone becomes dominant are not well understood, but recently resistance to apoptosis has been postulated. To test the hypothesis that the PIG-A mutation and absence of GPI-linked surface proteins directly confer resistance to apoptosis, we isolated peripheral granulocytes from 26 patients with PNH and 20 normal controls and measured apoptosis induced by serum starvation. Granulocytes from patients with PNH were relatively resistant to apoptosis (38.8% ± 14.1%) as compared with granulocytes from controls (55.0% ± 12.0%, P < .001). However, this resistance to apoptosis was not related to the dominance of the PNH clone because patients with a low percentage of GPI-deficient granulocytes had a similar rate of apoptosis as those with a high percentage of GPI-deficient granulocytes. Similarly, the resistance to granulocyte apoptosis was not influenced by the degree of neutropenia or a prior history of aplastic anemia. To investigate formally the importance of GPI-linked surface proteins in apoptosis, we introduced the PIG-A cDNA sequence into the JY5 GPI-negative B-lymphoblastoid cell line using two different methods: (1) stable transfection of a plasmid containing PIG-A, and (2) stable transduction of a retroviral vector containing PIG-A. We then measured rates of apoptosis induced either by Fas antibody, serum starvation, or γ-irradiation. With each stimulus, apoptosis of JY5 with stable surface expression of GPI-linked proteins was not statistically different from the parent JY5 cell line or the JY25 (GPI-positive) cell line. Our data confirm that granulocytes from patients with PNH have a relative resistance to apoptosis as compared with normal granulocytes. However, this resistance does not vary with the level of expression of GPI-linked proteins, and stable introduction of PIG-A cDNA with correction of GPI-linked surface expression does not change the rate of apoptosis. Taken together, our data do not support the hypothesis that the PIG-A mutation and absence of GPI-linked surface proteins directly confer resistance to apoptosis in PNH. We conclude that the resistance to apoptosis in PNH is not related to the PIG-A mutation, indicating that other factors must be important in the origin of this phenomenon and the clonal dominance observed in PNH.

CD59 (membrane inhibitor of reactive lysis, protectin) is a membrane protein whose functions include the inhibition of the insertion of the ninth component of complement into the target membrane. It belongs to a superfamily of proteins including Ly-6, elapid snake venom toxins, and urokinase receptor (UPAR); the members of the superfamily have a similar structure that includes four (in mammals five) disulfide bridges that maintain a three-dimensional conformation consisting of a central core, three finger-like "loops" extending from it and a small loop near the coboxyl end. We have used site directed mutagenesis to explore three aspects of the structure of CD59: 1) the role of the disulfide bridges in expression and function of the molecule; 2) the location of epitopes reacting with monoclonal antibodies to the molecule; and 3) the parts of the molecule that are critical to its function in inhibiting complement lysis. Mutant molecules in which the disulfides maintaining the finger-like loops (Cys3-Cys26, Cys19-Cys39, and Cys45-Cys63) were removed were not expressed on the cell surface. The mutation of the disulfide (Cys6-Cys13) resulted in no change in expression or function. The mutation of Cys64-Cys69 maintaining the small loop resulted in an expressed molecule with increased functional activity. The major epitope for 6 of 7 monoclonal antibodies was centered on Arg53 as the mutation 53Arg-->Ser resulted in a loss of interaction with these antibodies, as did the deletion of four nearby residues (Leu54-Asn57). The alteration 55Arg-->Ser resulted in loss of reactivity for some but not other antibodies. The reactivity with one monoclonal antibody, H19, was abrogated by the mutations 61Tyr-->Gly and 61Tyr-->Ala. Functional activity of the molecule was not adversely altered by mutations in the first and second loops; however, the 61Tyr-->Gly mutation was non-functional. The mutation of 61Tyr-->His diminished function but changes 61Tyr-->Ala and 61Tyr-->Phe had no effect on function. We conclude that the functional site of CD59 is located in this region of the molecule.

Recognizing that skilled history-taking is in danger of becoming a lost art, the American Board of Internal Medicine calls attention to the urgent need for internal medicine residency programs to ensure that these skills are taught and assessed. Although the Board's certification examination contains standardized items that test the physician's ability to use information from a patient's medical history, the written examination cannot assess the physician's ability to elicit that history. The Board believes that history-taking skills will become even more crucial as health care delivery changes, requiring more cost efficiency without sacrificing quality. By highlighting the skills of effective history-taking and strategies for assessment, the Board offers specific recommendations for its promotion as a key element of quality patient care.

We have characterized the erythrocytes, granulocytes, and platelets of 54 patients with paroxysmal nocturnal hemoglobinuria (PNH) with antibodies to glycosylphosphatidylinositol-anchored proteins (anti- CD55, anti-CD59, and anti-CD16) and flow cytometry to establish the usefulness of this technique in the diagnosis of this disorder. All patients demonstrated either completely (PNH III) or partially (PNH II) deficient red cells and granulocytes. Anti-CD59 best demonstrated PNH II red cells, which were present in 50% of the patients. The proportion of abnormal granulocytes was usually greater than the proportion of abnormal red cells; 37% of the patients had >80% abnormal granulocytes. Anti-CD55 did not delineate the erythrocyte populations as well as did anti-CD59. Either anti-CD55 or anti-CD59 could be used equally well to analyze granulocytes; anti-CD16 did not demonstrate cells of partial deficiency. Platelets could not be used for detailed analysis as the normal and abnormal populations were not well distinguished. Flow cytometry of erythrocytes using anti-CD59 or of granulocytes using either anti-CD55 or anti-CD59 provides the most accurate technique for the diagnosis of paroxysmal nocturnal hemoglobinuria; it is clearly more specific, more quantitative, and more sensitive than the tests for PNH that depend upon hemolysis by complement (the acidified serum lysis [Ham] test, the sucrose lysis test, and the complement lysis sensitivity [CLS] test).

The hematologic disorder paroxysmal nocturnal hemoglobinuria (PNH) occurs following an acquired somatic mutation in the Piga gene within a bone marrow stem cell. The progeny of this mutated cell cannot synthesize glycosylphosphatidylinositol (GPI) anchors, with a resultant deficiency in surface expression of all GPI-linked proteins. The protean clinical manifestations of PNH presumably result from the deficiency of these GPI-linked surface proteins. To explain the observation that neutrophils are affected at a significantly higher percentage than circulating erythrocytes and to analyze the proliferative rates of erythroid production in PNH, we studied 25 patients using flow cytometry. The fluorescent dye thiazole orange was used to detect reticulocytes, and CD59 monoclonal antibody was used to identify GPI-deficient cells. In contrast to the mature circulating erythrocytes, the percentage of abnormal reticulocytes was similar to the percentage of affected neutrophils. However, the vast majority of reticulocytes was completely GPI-deficient, ie, were type III cells, even in patients with only modest numbers of circulating type III erythrocytes. In addition, greater than 5% type II reticulocytes were identified in only 3 patients, although greater than 5% type II mature erythrocytes were identified in 10 of 25 patients. The results show that the erythroid and neutrophil bone marrow precursors have an equivalent proliferative advantage in PNH. The data also have important implications for the origin of type-II erythrocytes in PNH.

Introduction: Studies in patients with paroxysmal nocturnal hemoglobinuria (PNH) have shown that eculizumab reduces intravascular hemolysis, improves disease symptoms, and increases life expectancy. The objective of this analysis was to characterize, in a real-world setting, the benefit of eculizumab therapy in patients with PNH with no history of red blood cell (RBC) transfusion, with a special focus on high disease activity (HDA). Methods: The International PNH Registry is a prospective, observational study of patients with a PNH clone of 0.01-100%. Three patient populations were studied: 1) non-transfused untreated patients, 2) non-transfused eculizumab-treated patients, 3) eculizumab-treated patients who received ≥1 RBC transfusions in the 6 months prior to initiation of eculizumab. Transfused treated patients served as an additional comparison group. The primary outcome, assessed using multivariate linear regression, was mean absolute change from baseline to 6 months in LDH (U/L) in non-transfused treated and non-transfused untreated patients. Secondary outcomes were mean changes in patient-reported FACIT-Fatigue and EORTC-QLQ-C30 Fatigue scores from baseline to last available assessment. Results: A total of 1,547 patients were enrolled on or before April 30, 2012. The total study population (N=294) consisted of 1) 144 non-transfused untreated patients, 2) 45 non-transfused eculizumab-treated patients, and 3) 105 transfused eculizumab-treated patients. Of these, 136/144, 43/45, and 99/105 had HDA, respectively (Figure). At baseline, non-transfused untreated patients had the highest mean hemoglobin and lowest clone size (Table 1). Mean absolute reticulocytes were highest in the transfused treated group. Non-transfused untreated patients had the least mean absolute change in LDH from baseline to 6 months (-39.4 U/L) compared to non-transfused treated patients (-1318.8 U/L) and transfused treated patients (-1722.2 U/L) (Table 2). Non-transfused treated patients had a clinically meaningful mean percentage change in LDH compared with untreated patients (-69.9% versus -1.6%; p Conclusions: Data from the International PNH Registry demonstrate that patients with PNH carry a heavy disease burden. Findings show statistically significant and clinically meaningful differences in LDH reduction and improvement in fatigue in patients treated with eculizumab, irrespective of transfusion history, and in patients with HDA. Table 1. Baseline Patient Clinical Characteristics Non-transfused Transfused Untreated(N=144) Eculizumab Treated(N=45) Eculizumab Treated(N=105) Hemoglobin (g/L)Mean (SD) 114.1 (24.0) 103.3 (20.6) 101.3 (88.2) Absolute reticulocytes (x109 /L)Mean (SD) 128.7 (95.02) 124.4 (68.9) 157.4 (79.0) %GPI-deficient granulocytesMean (SD) 61.7 (28.0) 68.0 (24.2) 82.1 (18.4) History of TE, n (%) 16 (11.1) 13 (28.9) 23 (21.9) GPI, glycosylphosphatidylinositol; RBC, red blood cell; SD, standard deviation; TE, thrombotic event Table 2. Change in LDH and FACIT-Fatigue and EORTC Scores Non-transfused Transfused Untreated(N=144) Eculizumab Treated(N=45) Eculizumab Treated(N=105) LDH, U/LMean (SD) change from baseline to 6 months -39.4 (357.5) -1318.8 (1065.3) -1722.2 (1152.7) FACIT-Fatigue Absolute change nMean (SD) change from baseline to last available assessment 69 0.1 (9.6) 19 10.5 (11.6)* 29 5.5 (12.3) Clinically meaningful improvement, % (n) 24.6 (17) 73.7 (14) 55.2 (16) EORTC-Fatigue Absolute change n Mean (SD) change from baseline to last available assessment 69 −1.5 (26.9) 19 −22.8 (22.1)† 30 -11.9 (29.3) Clinically meaningful improvement, % (n) 33.3 (23) 84.2 (16) 46.7 (14) LDH, lactate dehydrogenase; SD, standard deviation *p Disclosures Almeida: Celgene: Consultancy; Novartis: Consultancy; Bristol Meyer Squibb: Speakers Bureau; Shire: Speakers Bureau. Bedrosian:Alexion Pharmaceutials: Employment, Equity Ownership, Patents & Royalties. Cole:Alexion Pharmaceuticals: Employment, Equity Ownership. Muus:Alexion Pharmaceuticals: Honoraria. Schrezenmeier:Alexion Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau. Szer:Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Shire Australia: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Pfizer Australia: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Alexion Pharmaceuticals Australasia Pty Ltd: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Sanofi: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Rosse:Alexion Pharmaceuticals: Consultancy.

The cellular receptor for urokinase-type plasminogen activator (uPAR) is a glycosylphosphatidylinositol (GPI)-anchored membrane protein that plays a central role in pericellular plasminogen activation. It contains 313 amino acid residues, including 28 cysteine residues in a pattern of three homologous repeats. The cysteine residue pattern suggests that uPAR belongs to a superfamily of proteins including CD59, murine Ly-6, and a variety of elapid snake venom toxins. A novel 1.7-kb uPAR cDNA was isolated that is missing exon 5 and that contains 380 bp not previously reported at the 5′ end. This cDNA was used to probe a human genomic library from which three clones were isolated and analyzed. The uPAR gene consists of 7 exons spread over 23 kb of genomic DNA. Exons 2, 4, and 6 code for homologous domains within the mature protein, as do exons 3, 5, and 7; CD59-like homologous pairs are encoded by exons 2–3, 4–5, and 6–7, respectively. The structure of the gene for uPAR further confirms the relationship of this molecule to the superfamily containing CD59, Ly-6, and the elapid snake venom toxins.

Information on life expectancy and risk factors for early death among patients with sickle cell disease (sickle cell anemia, sickle cell-hemoglobin C disease, and the sickle cell-beta-thalassemias) is needed to counsel patients, target therapy, and design clinical trials.We followed 3764 patients who ranged from birth to 66 years of age at enrollment to determine the life expectancy and calculate the median age at death. In addition, we investigated the circumstances of death for all 209 adult patients who died during the study, and used proportional-hazards regression analysis to identify risk factors for early death among 964 adults with sickle cell anemia who were followed for at least two years.Among children and adults with sickle cell anemia (homozygous for sickle hemoglobin), the median age at death was 42 years for males and 48 years for females. Among those with sickle cell-hemoglobin C disease, the median age at death was 60 years for males and 68 years for females. Among adults with sickle cell disease, 18 percent of the deaths occurred in patients with overt organ failure, predominantly renal. Thirty-three percent were clinically free of organ failure but died during an acute sickle crisis (78 percent had pain, the chest syndrome, or both; 22 percent had stroke). Modeling revealed that in patients with sickle cell anemia, the acute chest syndrome, renal failure, seizures, a base-line white-cell count above 15,000 cells per cubic millimeter, and a low level of fetal hemoglobin were associated with an increased risk of early death.Fifty percent of patients with sickle cell anemia survived beyond the fifth decade. A large proportion of those who died had no overt chronic organ failure but died during an acute episode of pain, chest syndrome, or stroke. Early mortality was highest among patients whose disease was symptomatic. A high level of fetal hemoglobin predicted improved survival and is probably a reliable childhood forecaster of adult life expectancy.

Paroxysmal nocturnal hemoglobinuria (PNH) is an acquired clonal hematologic disorder with multiple and varied clinical manifestations. The biochemical defect in PNH resides in the incomplete enzymatic assembly of glycosylphosphatidylinositol (GPI) anchors used for surface protein attachment. In all patients tested thus far, the defect is at the level of N-acetylglucosamine attachment to phosphatidylinositol (complementation class A defect). A human cDNA, Piga, that repairs cell lines with the class A defect has been recently cloned, making Piga a candidate gene for PNH. In the current study, using highly purified GPI- deficient granulocytes, we have performed Northern blot and reverse transcriptase polymerase chain reaction (RT-PCR) analysis of Piga in four patients with PNH. In each case, we have identified a mutation in the Piga coding sequence: three frameshift mutations were found, and a single nucleotide substitution (missense) mutation was identified. Our results provide convincing evidence that alterations in the Piga gene are responsible for PNH.

The defect in the biosynthesis of the glycosyl-phosphatidyl inositol (GPI) anchor in paroxysmal nocturnal hemoglobinuria (PNH) appears to be in the initial steps. In biosynthetic studies using [3H]mannose, abnormal granulocytes of eight patients, and B lymphocytes transformed by Epstein-Barr virus of six different patients synthesized dolichyl phosphoryl mannose, but little or no later mannosylated intermediates. When fused with murine cell lines known to be deficient at different biosynthetic steps of the GPI anchor, the GPI-anchor-deficient granulocytes of 21/21 patients and lymphocytes from 6/6 patients complemented all murine cell lines except those of class A; cells of this class are not able to add N-acetylglucosamine to phosphatidylinositol. These studies indicate that the defect in GPI- anchor synthesis in PNH is early in the pathway, and is the same as that of class A mutants, but may be partial in some patients, resulting in the production of small amounts of mannosylated intermediates.

In recounting the history of the development of knowledge about PNH, the roles of the clinician, the basic scientist, and the clinician-investigator are apparent. Without the observations of the clinicians, the problem could not be posed. Without the contributions from basic science (the biochemistry of complement, the biology of glycosyl-phosphatidylinositol anchors, etc), the information necessary to the solution of the problem would not be available. Without the synthesis of the clinician-investigator, the two elements would not be fused to result in knowledge about the disease.

Background: Paroxysmal nocturnal hemoglobinuria (PNH) is a rare hematopoietic stem cell disorder characterized by a somatic mutation in the PIGA gene, leading to a deficiency of proteins linked to the cell membrane via glycophosphatidylinositol (GPI) anchors. While flow cytometry is the method of choice for identifying cells deficient in GPI-linked proteins and is, therefore, necessary for the diagnosis of PNH, to date there has not been an attempt to standardize the methodology used to identify these cells. Methods: In this document, we present a consensus effort that describes flow cytometric procedures for detecting PNH cells. Results: We discuss clinical indications and offer recommendations on data interpretation and reporting but mostly focus on analytical procedures important for analysis. We distinguish between routine analysis (defined as identifying an abnormal population of 1% or more) and high-sensitivity analysis (in which as few as 0.01% PNH cells are detected). Antibody panels and gating strategies necessary for both procedures are presented in detail. We discuss methods for assessing PNH populations in both white blood cells and red blood cells and the relative advantages of measuring each. We present steps needed to validate the more elaborate high-sensitivity techniques, including the need for careful titration of reagents and determination of background rates in normal populations, and discuss technical pitfalls that might affect interpretation. Conclusions: This document should both enable laboratories interested in beginning PNH testing to establish a valid procedure and allow experienced laboratories to improve their techniques. © 2010 Clinical Cytometry Society

During the past decade a large body of experimental and clinical studies has focused on the hypothesis that nitric oxide (NO) depletion by plasma hemoglobin in the microcirculation plays a central role in the pathogenesis of many manifestations of sickle cell disease (SCD), particularly pulmonary hypertension. We have carefully examined those studies and believe that the conclusions drawn from them are not adequately supported by the data. We agree that NO depletion may well play a role in the pathophysiology of other hemolytic states such as paroxysmal nocturnal hemoglobinuria, in which plasma hemoglobin concentrations are often at least an order of magnitude greater than in SCD. Accordingly, we conclude that clinical trials in SCD designed to increase the bioavailability of NO or association studies in which SCD clinical manifestations are related to plasma hemoglobin via its surrogates should be viewed with caution.

A randomized, controlled clinical trial established the efficacy and safety of short-term use of hydroxyurea in adult sickle cell anemia. To examine the risks and benefits of long-term hydroxyurea usage, patients in this trial were followed for 17.5 years during which they could start or stop hydroxyurea. The purpose of this follow-up was to search for adverse outcomes and estimate mortality. For each outcome and for mortality, exact 95% confidence intervals were calculated, or tests were conducted at alpha = 0.05 level (P-value

The gene for CD59 [membrane inhibitor of reactive lysis (MIRL), protectin], a phosphatidylinositol-linked surface glycoprotein that regulates the formation of the polymeric C9 complex of complement and that is deficient on the abnormal hematopoietic cells of patients with paroxysmal nocturnal hemoglobinuria, consists of four exons spanning 20 kilobases. The untranslated first exon is preceded by a G+C-rich promoter region that lacks a consensus TATA or CAAT motif. The second exon encodes the hydrophobic leader sequence of the protein, and the third exon encodes the amino-terminal portion of the mature protein. The fourth exon encodes the remainder of the mature protein, including the hydrophobic sequence necessary for glycosyl-phosphatidylinositol anchor attachment. The structure of the CD59 gene is very similar to that encoding Ly-6, a murine glycoprotein with which CD59 has some structural similarity. The striking similarity in gene structure is further evidence that the two proteins belong to a superfamily of proteins that may also include the urokinase plasminogen-activator receptor and a squid glycoprotein of unknown function.

To investigate the biosynthesis of the glycosylphosphatidylinositol (GPI) anchor in the granulocytes of paroxysmal nocturnal hemoglobinuria (PNH), the glycolipids of granulocytes from PNH patients and normal volunteers were biosynthetically labeled with [3H]mannose in the presence of tunicamycin. Extracted glycolipids were examined by thin- layer chromatography and compared with known biosynthetic intermediates. Normal granulocytes consistently showed [3H]mannose incorporation into the complete GPI core, several GPI biosynthetic intermediates, and dolichol phosphate mannose (DPM). The granulocytes of 10 patients with PNH that had no expression of CD55 and CD59 on greater than 95% of the cells were able to incorporate [3H]mannose into DPM, but were not able to incorporate detectable amounts into the complete GPI core. THus, PNH granulocytes do not synthesize detectable amounts of the complete GPI core and this defect likely accounts for the absence of GPI-linked membrane proteins on hematopoietic cells in this syndrome.

The human erythrocyte bears a number of proteins anchored to the outer membrane surface via a phosphatidylinositol-glycan linkage. This class of proteins includes several complement regulatory proteins (including decay-accelerating factor, CD59 antigen (protectin), and C8 binding protein) as well as several enzymes and at least one protein important in cell-cell interaction. In addition, a number of blood group antigens have been identified to reside on proteins with phosphatidylinositol anchors. One blood group (Cromer) resides on DAF. Study of variants in this blood group system has led to interesting information about the function and expression of this protein. Several other blood groups, such as JMH and Holley/Gregory, appear to reside on as yet unidentified phosphatidylinositol-linked proteins. In paroxysmal nocturnal haemoglobinuria, a variable proportion of red cells fail to express or express weakly all phosphatidylinositol-linked proteins. The origin of this deficiency is now being worked out. In addition, individuals with inherited deficiency of DAF or CD59 (protectin) have been identified. Only the latter deficiency leads to a PNH-like syndrome.

Acute episodes of pain are the principal symptom of sickle cell disease, but little is known about the epidemiologic features of these episodes or risk factors for them, nor is it known whether patients with high rates of such episodes die prematurely. We prospectively studied the natural history of sickle cell disease in 3578 patients ranging from newborns to persons up to 66 years old who were followed at clinical centers across the United States.There were 12,290 episodes of pain in 18,356 patient-years. The average rate was 0.8 episode per patient-year in sickle cell anemia, 1.0 episode per patient-year in sickle beta 0-thalassemia, and 0.4 episode per patient-year in hemoglobin SC disease and sickle beta(+)-thalassemia. The rate varied widely within each of these four groups--e.g., 39 percent of patients with sickle cell anemia had no episodes of pain, and 1 percent had more than six episodes per year. The 5.2 percent of patients with 3 to 10 episodes per year had 32.9 percent of all episodes. Among patients with sickle cell anemia who were more than 20 years old, those with high rates of pain episodes tended to die earlier than those with low rates. High rates were associated with a high hematocrit and low fetal hemoglobin levels. alpha-Thalassemia had no effect on pain apart from its association with an increased hematocrit.The "pain rate" (episodes per year) is a measure of clinical severity and correlates with early death in patients with sickle cell anemia over the age of 20. Even when the fetal hemoglobin level is low, one can predict that small increments in the level may have an ameliorating effect on the pain rate and may ultimately improve survival. This outcome is particularly encouraging to investigators studying hydroxyurea and other treatments designed to increase the fetal hemoglobin level.

In 1,814 patients with sickle cell disease who had been transfused, the overall rate of alloimmunization to erythrocyte antigens was 18.6%. The rate of alloimmunization in this group appears to be an explicit function of the number of transfusions received because it increases exponentially with increasing numbers of transfusions. Alloimmunization usually occurred with less than 15 transfusions, although the rate of alloimmunization continued to increase when more transfusions were given. The rate of alloimmunization was less in patients with hemoglobin SC disease and sickle-beta+ thalassemia because these patients had received fewer transfusions. Children less than 10 years old had a slightly lower rate of alloimmunization than patients in other age groups even after correction for the number of transfusions given. Women were more frequently alloimmunized than men; this was largely due to the fact that women received more transfusions than men, but in the age group 16 to 20 years the increase may have been due in part to alloimmunization owing to pregnancy. Forty-five percent of those alloimmunized made antibodies of only one specificity; 17% made four or more antibodies reacting with different antigens. Antibodies to the C and E antigens of the Rh group, the Kell antigen, and the Lewis antigens were most commonly made. These findings may be important in formulating a rational transfusion policy in sickle cell disease.

Paroxysmal nocturnal hemoglobinuria (PNH) is an acquired disorder associated with absence of expression of phosphatidylinositol (PI)- linked membrane proteins from circulating hematopoietic cells of multiple lineages. Recent work demonstrated that decay accelerating factor, one such PI-linked protein, bears the Cromer-related blood group antigens. This study demonstrated that other high incidence antigens, including Cartwright (Yta/Ytb), Holley-Gregory (Hy/Gya), John Milton Hagen (JMH), and Dombrock (Doa/Dob), are absent from the complement-sensitive (PNH III) erythrocytes of patients with PNH. The relatively normal, complement-insensitive erythrocytes from the same patients express these antigens normally. Therefore, these antigens most likely reside on PI-linked proteins absent from PNH III, but not PNH I, erythrocytes.

The blood cells in paroxysmal nocturnal hemoglobinuria (PNH) lack several proteins, including some that regulate the activation of complement on the cell surface. Decay-accelerating factor (DAF), the first such protein to be identified, is, like all the missing proteins, affixed to the membrane by a glycolipid anchor containing phosphotidylinositol, hexoses, and ethanolamine. The defect in PNH appears to be an inability to place or maintain proteins linked in this way on the cell surface.

The 65 kDa C8-binding protein or homologous restriction factor ( C8bp HRF ) protects cells from complement (C)-mediated lysis by binding to C8 and abrogating lytic channel formation. Human C8bp HRF is shown here to be immunologically related to human C8 and C9 and to murine lymphocyte poreforming protein (PFP, perforin). Polyclonal antibodies raised against purified C8, C9 and perforin react with C8bp HRF . The antigenic epitopes shared by these four proteins are limited to cysteine-rich or disulfide bridge-masked domains. Only complement proteins or perforin that have been disulfide-reduced elicit the production of cross-reactive antibodies when used as immunogens. Analogously, only C8bp HRF that has been disulfide-reduced reacts with these antibodies. These results suggest that C8bp HRF may belong to the complement/perforin supergene family. The function of homologous domains shared by these four proteins remains to be elucidated.

A 21-year-old white worn was referred for evaluation of hemolytic anemia after a 9-day history of marked hemoglobinuria, jaundice, and weakness. The patient’s hematocrit was 18&, despite at least eight transfusions over the previous week, and the reticulocyte count was < 1%. Serologic evaluation revealed a weakly positive direct antiglobulin test with antic-C3 only The serum contained coldand warm-reactinga nti-N Dithiothreitol had no effect on either the cold- or the warm-reacting anti-N activity, and radoimmunoassay with monoclonal anti-IgG was strongly positive, indicating that both the cold- and the warm-reacting anti-N reactivity resided in the IgG fraction. The patient was treated with N – ‘N’ + red cell transfusions, prednisone, and azathioprine and gradually became transfusioni ndependent. Postrecovery typing revealed her red cells to be M+N+S+s+. This constitutes the third case of autoimmune hemolytic anemia associated with IgG autoanti-N. The marked hemoglobinuria and reticulocytopenia are unique features of this case.

Hemolytic anemia due to immune function is one of the major causes of acquired hemolytic anemia. In recent years, as more is known about the immune system, these entities have become better understood and their treatment improved. In this section, we will discuss three areas in which this progress has been apparent.In Section I, Dr. Peter Hillmen outlines the recent findings in the pathogenesis of paroxysmal nocturnal hemoglobinuria (PNH), relating the biochemical defect (the lack of glycosylphosphatidylinositol [GPI]-linked proteins on the cell surface) to the clinical manifestations, particularly hemolysis (and its effects) and thrombosis. He discusses the pathogenesis of the disorder in the face of marrow dysfunction insofar as it is known. His major emphasis is on innovative therapies that are designed to decrease the effectiveness of complement activation, since the lack of cellular modulation of this system is the primary cause of the pathology of the disease. He recounts his considerable experience with a humanized monoclonal antibody against C5, which has a remarkable effect in controlling the manifestations of the disease. Other means of controlling the action of complement include replacing the missing modulatory proteins on the cell surface; these studies are not as developed as the former agent.In Section II, Dr. Alan Schreiber describes the biochemistry, genetics, and function of the Fcγ receptors and their role in the pathobiology of autoimmune hemolytic anemia and idiopathic thrombocytopenic purpura due to IgG antibodies. He outlines the complex varieties of these molecules, showing how they vary in genetic origin and in function. These variations can be related to three-dimensional topography, which is known in some detail. Liganding IgG results in the transduction of a signal through the tyrosine-based activation motif and Syk signaling. The role of these receptors in the pathogenesis of hematological diseases due to IgG antibodies is outlined and the potential of therapy of these diseases by regulation of these receptors is discussed.In Section III, Dr. Wendell Rosse discusses the forms of autoimmune hemolytic anemia characterized by antibodies that react preferentially in the cold–cold agglutinin disease and paroxysmal cold hemoglobinuria (PCH). The former is due to IgM antibodies with a common but particular structure that reacts primarily with carbohydrate or carbohydrate-containing antigens, an interaction that is diminished at body temperature. PCH is a less common but probably underdiagnosed illness due to an IgG antibody reacting with a carbohydrate antigen; improved techniques for the diagnosis of PCH are described. Therapy for the two disorders differs somewhat because of the differences in isotype of the antibody. Since the hemolysis in both is primarily due to complement activation, the potential role of its control, as by the monoclonal antibody described by Dr. Hillmen, is discussed.

To determine and directly compare the clinical course of white and Asian patients with paroxysmal nocturnal hemoglobinuria (PNH), data were collected for epidemiologic analysis on 176 patients from Duke University and 209 patients from Japan. White patients were younger with significantly more classical symptoms of PNH including thrombosis, hemoglobinuria, and infection, while Asian patients were older with more marrow aplasia. The mean fraction of CD59-negative polymorphonuclear cells (PMN) at initial analysis was higher among Duke patients than Japanese patients. In both cohorts, however, a larger PNH clone was associated with classical PNH symptoms, while a smaller PNH clone was associated with marrow aplasia. Thrombosis was significantly more prevalent in white patients than Asian patients, and was associated with a significantly higher proportion of CD59-negative PMN. For individual patients, CD59-negative populations varied considerably over time, but a decreasing PNH clone portended hematopoietic failure. Survival analysis revealed a similar death rate in each group, although causes of death were different and significantly more Duke patients died from thrombosis. Japanese patients had a longer mean survival time (32.1 yr vs. 19.4 yr), although Kaplan-Meier survival curves were not significantly different. Poor survival in both groups was associated with age over 50 years, severe leukopenia/neutropenia at diagnosis, and severe infection as a complication; additionally, thrombosis at diagnosis or follow-up for Duke patients and renal failure for Japanese patients were poor prognostic factors. These data identify important differences between white and Asian patients with PNH. Identification of prognostic factors will help the design of prospective clinical trials for PNH.

The clinical pathology of paroxysmal nocturnal hemoglobinuria (PNH) involves 3 complications: hemolytic anemia, thrombosis, and hematopoietic deficiency. The first 2 are clearly the result of the cellular defect in PNH, the lack of proteins anchored to the membrane by the glycosylphosphatidylinositol anchor. The hemolytic anemia results in syndromes primarily related to the fact that the hemolysis is extracellular. Thrombosis is most significant in veins within the abdomen, although a number of other thrombotic syndromes have been described. The hematopoietic deficiency may be the same as that in aplastic anemia, a closely related disorder, and may not be due to the primary biochemical defect. The relationship to aplastic anemia suggests a nomenclature that emphasizes the predominant clinical manifestations in a patient. This relationship does not explain cases that appear to be related to myelodysplastic syndromes or the transition of some cases of PNH to leukemia. Treatment, except for bone marrow transplantation, remains noncurative and in need of improvement.

Paroxysmal nocturnal hemoglobinuria (PNH) is an acquired clonal hematopoietic stem cell disorder caused by PIG-A mutations. To assess clonal expansion in PNH over time, patients with serial testing by flow cytometry (interval of at least one year) were analyzed. This study involved 164 patients with PNH from Duke (DP) and 151 patients from Japan (JP). The mean fraction of PMNs deficient in CD59 (mean±SE) was 75.2±4.2% in DP and 40.0 + 8.3% (n=21) in JP at the initial analysis, and were 74.1 ±4.7% and 50.7 + 8.6% at the latest analysis (P=NS). However, in individual cases, the proportion of affected PMNs varied considerably from -84% to +98%. Some DP and JP pts, however, had a diminution in their CD59-deficient PMNs over time, which was associated with the development of overall hematopoietic failure (P=.04 for DP, P=.05 for JP). These data illustrate the complexity of clonal expansion in PNH, and the marked variability over time. GPI-deficient populations vary considerably over time for individual patients, but a decreasing PNH clone indicates impending hematopoietic failure. Correlation between clonal expansion or diminution and the development or recovery from aplasia will help our understanding of the natural history of PNH.

The history of the development of the understanding of the natural history of paroxysmal nocturnal hemoglobinuria (PNH) illustrates the interaction between basic science and clinical problems. Through application of the knowledge obtained in the laboratory, a better understanding of the clinical problems has been achieved.

PNH, which is characterized by intravascular hemolysis and venous thrombosis, is an uncommon disorder of hematopoietic stem cells with an acquired somatic mutation of PIG-A. An understanding of the natural history of PNH is essential to improve therapy. To determine and to directly compare the clinical courses of PNH patients from the USA and Japan, data were collected for 385 patients with PNH. There were 176 patients from Duke (DP) and 209 patients from Japan (JP). The mean age at diagnosis (mean ± SE) was 32.8 ±1.2 years (4-80) in DP, and 45.1 ±1.3 years (10-86) in JP. The incidence of various chnical events was analyzed. These analyses provide important diagnostic and long-term data on two large cohorts of PNH patients, and identify important differences between Caucasian and Asian patients with PNH. Caucasians tend to be younger and have classical symptoms of PNH including thrombosis, while Asians tend to be older and have symptoms of aplasia. Multivariate analysis of factors influencing survival was also undertaken. By this study, estimates of PNH prognostic factors may provide a better understanding of the complications of the disease so that therapeutic interventions may be sought. Further, by noting differences in the two populations, possible genetic modifiers of the course of the disease may be identified for further investigation.

Human erythrocytes are terminally differentiated, nonendocytic cells that lack all intracellular organelles. Here we show that their plasma membranes contain detergent-resistant membrane rafts that constitute a small fraction (4%) of the total membrane protein, with a complex mixture of proteins that differentially associate with rafts. Depletion of raft-cholesterol abrogates association of all proteins with no significant effect on cholesterol:protein ratios in the rest of the membrane, lipid asymmetry, deformability, or transport properties of the bilayer, indicating that cholesterol is critical for protein assembly into rafts and suggesting that rafts have little influence on several erythrocyte functions. Erythrocytes from patients with paroxysmal nocturnal hemoglobinuria, which lack glycosylphosphatidylinositol-anchored proteins, show significant elevation in raft-cholesterol but no increase in raft protein association, suggesting that raft assembly does not require glycosylphosphatidylinositol-anchored proteins, raft proteins do not bind directly to cholesterol, and only threshold levels of raft-cholesterol are critical for protein recruitment. Loss of glycosylphosphatidylinositol-anchored proteins had no effect on erythrocytic infection by malarial parasite or movement of raft markers into the parasite's vacuole. However, infection is blocked following raft-cholesterol disruption, suggesting that erythrocyte rafts can be functionally exploited and providing the first evidence for the involvement of host rafts in an apicomplexan infection.

Publisher Summary The history of paroxysmal nocturnal hemoglobinuria (PNH) shows many examples of the role of careful clinical observation and the application of the methods of science available at the time in unraveling this complex disorder. It was one of the first discrete hematological entities to be described, undoubtedly due to the dramatic content of its primary symptom—hemoglobinuria. The passage of red, dark brown, purple, or black urine is readily noted by the patient and induces a distinct impression on the physician. As with all science, it is characterized by a series of platforms, which solidify understanding and are built upon, as more observations are made and better methods become available. PNH seems to be the result of interaction between an acquired somatic defect in the hematopoietic precursors and an alteration in hematopoiesis by a presumably unrelated process. As in the past, the investigation of these factors will provide information not only about this disease, but about human biology in general and other diseases in particular.