Faculty Opinions recommendation of A novel approach to preventing the hemolysis of paroxysmal nocturnal hemoglobinuria: both complement-mediated cytolysis and C3 deposition are blocked by a monoclonal antibody specific for the alternative pathway of complement.

2010 ◽  
Author(s):  
Antonio Risitano ◽  
Fabiana Perna
Keyword(s):  
Monoclonal Antibody ◽  
Paroxysmal Nocturnal Hemoglobinuria ◽  
Alternative Pathway ◽  
Novel Approach ◽  
Alternative Pathway Of Complement

A novel approach to preventing the hemolysis of paroxysmal nocturnal hemoglobinuria: both complement-mediated cytolysis and C3 deposition are blocked by a monoclonal antibody specific for the alternative pathway of complement

Blood ◽  
2010 ◽  
Vol 115 (11) ◽  
pp. 2283-2291 ◽  
Author(s):  
Margaret A. Lindorfer ◽  
Andrew W. Pawluczkowycz ◽  
Elizabeth M. Peek ◽  
Kimberly Hickman ◽  
Ronald P. Taylor ◽  
...  
Keyword(s):  
Monoclonal Antibody ◽  
Paroxysmal Nocturnal Hemoglobinuria ◽  
Alternative Pathway ◽  
Significant Proportion ◽  
Complement C3 ◽  
Classical Pathway ◽  
Immune Functions ◽  
Intravascular Hemolysis ◽  
Alternative Pathway Of Complement

Abstract The clinical hallmark of paroxysmal nocturnal hemoglobinuria (PNH) is chronic intravascular hemolysis that is a consequence of unregulated activation of the alternative pathway of complement (APC). Intravascular hemolysis can be inhibited in patients by treatment with eculizumab, a monoclonal antibody that binds complement C5 thereby preventing formation of the cytolytic membrane attack complex of complement. However, in essentially all patients treated with eculizumab, persistent anemia, reticulocytosis, and biochemical evidence of hemolysis are observed; and in a significant proportion, their PNH erythrocytes become opsonized with complement C3. These observations suggest that PNH patients treated with eculizumab are left with clinically significant immune-mediated hemolytic anemia because the antibody does not block APC activation. With a goal of improving PNH therapy, we characterized the activity of anti-C3b/iC3b monoclonal antibody 3E7 in an in vitro model of APC-mediated hemolysis. We show that 3E7 and its chimeric-deimmunized derivative H17 block both hemolysis and C3 deposition on PNH erythrocytes. The antibody is specific for the APC C3/C5 convertase because classical pathway–mediated hemolysis is unaffected by 3E7/H17. These findings suggest an approach to PNH treatment in which both intravascular and extravascular hemolysis can be inhibited while preserving important immune functions of the classical pathway of complement.

Hematin Promotes Complement Alternative Pathway-Mediated Deposition of C3 Activation Fragments on Human Erythrocytes: Potential Implications for the Pathogenesis of Anemia in Malaria.

Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 839-839
Author(s):  
Ronald P. Taylor ◽  
Andrew W. Pawluczkowycz ◽  
Margaret A. Lindorfer ◽  
John W. Waitumbi
Keyword(s):  
Monoclonal Antibody ◽  
B Cells ◽  
Alternative Pathway ◽  
Complement Alternative Pathway ◽  
Western Blots ◽  
Marginal Zone B Cells ◽  
Immune Adherence ◽  
Alternative Pathway Of Complement ◽  
Childhood Malaria ◽  
Covalently Bound

Abstract Childhood malaria caused by Plasmodium falciparum (pf) is often characterized by severe anemia at low parasite burdens; the mechanism(s) responsible for this pathology remain to be defined. We have reported that erythrocyte (E) CR1, the immune adherence receptor specific for C3b, is reduced during anemia in childhood malaria, suggesting a possible role for complement in E destruction. Intravascular lysis of infected E by pf leads to release of E breakdown products hemoglobin and hematin, which have inflammatory properties. Free hematin can bind to E, and we find that in serum and in whole blood anti-coagulated with lepirudin, moderate concentrations of hematin activate the alternative pathway of complement and promote deposition of C3 activation and breakdown products on E. We documented C3 deposition by flow cytometry, and additional fluorescence microscopy studies revealed that most of the deposited C3 fragments are located in close juxtaposition to CR1. Western blots confirmed that the C3 fragments are indeed covalently bound to the E, and immunoprecipitation experiments indicated that a fraction of the deposited C3 is covalently bound to CR1. The degree of C3 fragment deposition is directly correlated with E CR1 levels, both within a given donor’s E population and when E from different donors are compared. E opsonized with complement in the presence of hematin form rosettes with Raji cells, through interaction with CR2, the C3dg receptor expressed on several types of B cells including splenic marginal zone B cells. Thus, hematin-mediated complement activation and C3 fragment deposition on E may promote accelerated splenic (or liver) clearance of the youngest E, which have the most CR1, leading to sudden onset of anemia along with reduction of mean CR1 on surviving E. A monoclonal antibody specific for C3b, mAb 3E7, previously demonstrated to inhibit the alternative pathway of complement, completely blocks the C3 fragment deposition reaction. Use of this monoclonal antibody in non-human primate models of malaria may provide insight into mechanisms of erythrocyte destruction and thus aid in the development of therapies based on inhibiting the alternative pathway of complement.

scholarly journals Molecular basis of the enhanced susceptibility of the erythrocytes of paroxysmal nocturnal hemoglobinuria to hemolysis in acidified serum

Blood ◽  
1991 ◽  
Vol 78 (3) ◽  
pp. 820-829 ◽  
Author(s):  
LA Wilcox ◽  
JL Ezzell ◽  
NJ Bernshaw ◽  
CJ Parker
Keyword(s):  
Paroxysmal Nocturnal Hemoglobinuria ◽  
Alternative Pathway ◽  
Regulatory Protein ◽  
Membrane Attack Complex ◽  
Factor H ◽  
Alternative Pathways ◽  
Complement Control Protein ◽  
Alternative Pathway Of Complement ◽  
Regulatory Effects ◽  
And Control

Abstract When incubated in acidified serum, the erythrocytes of paroxysmal nocturnal hemoglobinuria (PNH) are hemolyzed through activation of the alternative pathway of complement (APC), but normal erythrocytes are resistant to this process. PNH cells are deficient in decay- accelerating factor (DAF), a complement regulatory protein that inhibits the activity of both the classical and the alternative pathways. However, deficiency of DAF alone does not account entirely for the aberrant effects of acidified serum on PNH cells. Recently, we have shown that PNH erythrocytes are also deficient in another complement control protein called membrane inhibitor of reactive lysis (MIRL) that restricts complement-mediated lysis by blocking formation of the membrane attack complex (MAC). To determine the effects of the DAF and MIRL on susceptibility to acidified serum lysis, PNH cells were repleted with the purified proteins. DAF partially inhibited acidified serum lysis by blocking the activity of the amplification C3 convertase. MIRL inhibited acidified serum lysis both by blocking the activity of the MAC and by inhibiting the activity the C3 convertase. When DAF function was blocked with antibody, normal erythrocytes became partially susceptible to acidified serum lysis. By blocking MIRL, cells were made completely susceptible to lysis, and control of C3 convertase activity was partially lost. When both DAF and MIRL were blocked, the capacity of normal erythrocytes to control the activity of the APC and the MAC was destroyed, and the cells hemolyzed even in unacidified serum. These studies demonstrate that DAF and MIRL act in concert to control susceptibility to acidified serum lysis; of the two proteins, MIRL is the more important. In addition to its regulatory effects on the MAC, MIRL also influences the activity of the C3 convertase of the APC. Further, in the absence of DAF and MIRL, the plasma regulators (factor H and factor I) lack the capacity to control membrane- associated activation of the APC.

scholarly journals Complement in hemolytic anemia

Blood ◽  
2015 ◽  
Vol 126 (22) ◽  
pp. 2459-2465 ◽  
Author(s):  
Robert A. Brodsky
Keyword(s):  
Paroxysmal Nocturnal Hemoglobinuria ◽  
Alternative Pathway ◽  
Atypical Hemolytic Uremic Syndrome ◽  
Reticuloendothelial System ◽  
Immunoglobulin M ◽  
Regulatory Proteins ◽  
Cold Agglutinin Disease ◽  
Complement Regulatory Proteins ◽  
Uremic Syndrome ◽  
Alternative Pathway Of Complement

Abstract Complement is increasingly being recognized as an important driver of human disease, including many hemolytic anemias. Paroxysmal nocturnal hemoglobinuria (PNH) cells are susceptible to hemolysis because of a loss of the complement regulatory proteins CD59 and CD55. Patients with atypical hemolytic uremic syndrome (aHUS) develop a thrombotic microangiopathy (TMA) that in most cases is attributable to mutations that lead to activation of the alternative pathway of complement. For optimal therapy, it is critical, but often difficult, to distinguish aHUS from other TMAs, such as thrombotic thrombocytopenic purpura; however, novel bioassays are being developed. In cold agglutinin disease (CAD), immunoglobulin M autoantibodies fix complement on the surface of red cells, resulting in extravascular hemolysis by the reticuloendothelial system. Drugs that inhibit complement activation are increasingly being used to treat these diseases. This article discusses the pathophysiology, diagnosis, and therapy for PNH, aHUS, and CAD.

Paroxysmal Nocturnal Hemoglobinuria: An Historical Overview

Hematology ◽  
2008 ◽  
Vol 2008 (1) ◽  
pp. 93-103 ◽  
Author(s):  
Charles J. Parker
Keyword(s):  
Paroxysmal Nocturnal Hemoglobinuria ◽  
Genetic Basis ◽  
Alternative Pathway ◽  
History Of ◽  
Alternative Pathway Of Complement ◽  
The Times ◽  
The 19Th Century ◽  
German Physician ◽  
Paroxysmal Cold Hemoglobinuria ◽  
Scientific Achievements

Abstract The clinical hallmark of paroxysmal nocturnal hemoglobinuria (PNH) is episodic hemoglobinuria, and it was this feature that captured the attention of European physicians in the latter half of the 19th century, resulting in careful observational studies that established PNH as an entity distinct from paroxysmal cold hemoglobinuria and march hemoglobinuria. Curiosity about the etiology of the nocturnal aspects of the hemoglobinuria led the German physician Paul Strübing to develop the prescient hypothesis that the erythrocytes of PNH are abnormally sensitive to hemolysis when the plasma is acidified during sleep because of accumulation of carbon dioxide and lactic acid as a result of slowing of the circulation. Investigation of the intricate pathophysiology that underlies the abnormal sensitivity of PNH erythrocytes to hemolysis in acidified serum produced a number of remarkable scientific achievements that involved discovery of the alternative pathway of complement, identification of the membrane proteins that regulate complement, discovery of a novel mechanism for attachment of proteins to the cell surface, and identification of the genetic basis of the disease. These discoveries were made steadily over a period of more than 100 years, and each generation of physicians and scientists made important contributions to the field. The mysteries of PNH have been solved in a particularly satisfying way because the precision and orderliness of the solutions made clearly understandable what had seemed at the times prior to resolution to be problems of nearly insurmountable complexity. The history of PNH is an inspirational reminder of the elegant complexity of nature, the rewards of curiosity and the power and beauty of science.

scholarly journals Complement in hemolytic anemia

Hematology ◽  
2015 ◽  
Vol 2015 (1) ◽  
pp. 385-391 ◽  
Author(s):  
Robert A. Brodsky
Keyword(s):  
Paroxysmal Nocturnal Hemoglobinuria ◽  
Alternative Pathway ◽  
Atypical Hemolytic Uremic Syndrome ◽  
Reticuloendothelial System ◽  
Immunoglobulin M ◽  
Regulatory Proteins ◽  
Cold Agglutinin Disease ◽  
Complement Regulatory Proteins ◽  
Uremic Syndrome ◽  
Alternative Pathway Of Complement

Abstract Complement is increasingly being recognized as an important driver of human disease, including many hemolytic anemias. Paroxysmal nocturnal hemoglobinuria (PNH) cells are susceptible to hemolysis because of a loss of the complement regulatory proteins CD59 and CD55. Patients with atypical hemolytic uremic syndrome (aHUS) develop a thrombotic microangiopathy (TMA) that in most cases is attributable to mutations that lead to activation of the alternative pathway of complement. For optimal therapy, it is critical, but often difficult, to distinguish aHUS from other TMAs, such as thrombotic thrombocytopenic purpura; however, novel bioassays are being developed. In cold agglutinin disease (CAD), immunoglobulin M autoantibodies fix complement on the surface of red cells, resulting in extravascular hemolysis by the reticuloendothelial system. Drugs that inhibit complement activation are increasingly being used to treat these diseases. This article discusses the pathophysiology, diagnosis, and therapy for PNH, aHUS, and CAD.

Complement in hemolytic anemia

Hematology ◽  
2015 ◽  
Vol 2015 (1) ◽  
pp. 385-391 ◽  
Author(s):  
Robert A. Brodsky
Keyword(s):  
Paroxysmal Nocturnal Hemoglobinuria ◽  
Alternative Pathway ◽  
Atypical Hemolytic Uremic Syndrome ◽  
Reticuloendothelial System ◽  
Immunoglobulin M ◽  
Regulatory Proteins ◽  
Cold Agglutinin Disease ◽  
Complement Regulatory Proteins ◽  
Uremic Syndrome ◽  
Alternative Pathway Of Complement

Complement is increasingly being recognized as an important driver of human disease, including many hemolytic anemias. Paroxysmal nocturnal hemoglobinuria (PNH) cells are susceptible to hemolysis because of a loss of the complement regulatory proteins CD59 and CD55. Patients with atypical hemolytic uremic syndrome (aHUS) develop a thrombotic microangiopathy (TMA) that in most cases is attributable to mutations that lead to activation of the alternative pathway of complement. For optimal therapy, it is critical, but often difficult, to distinguish aHUS from other TMAs, such as thrombotic thrombocytopenic purpura; however, novel bioassays are being developed. In cold agglutinin disease (CAD), immunoglobulin M autoantibodies fix complement on the surface of red cells, resulting in extravascular hemolysis by the reticuloendothelial system. Drugs that inhibit complement activation are increasingly being used to treat these diseases. This article discusses the pathophysiology, diagnosis, and therapy for PNH, aHUS, and CAD.

scholarly journals Immunological and Therapeutic Strategies against Salmonid Cryptobiosis

2010 ◽  
Vol 2010 ◽  
pp. 1-9 ◽  
Author(s):  
Patrick T. K. Woo
Keyword(s):  
Monoclonal Antibody ◽  
Single Dose ◽  
Salvelinus Fontinalis ◽  
Alternative Pathway ◽  
Clinical Signs ◽  
Abdominal Distension ◽  
Therapeutic Strategies ◽  
Brook Charr ◽  
Alternative Pathway Of Complement ◽  
High Parasitaemias

Salmonid cryptobiosis is caused by the haemoflagellate,Cryptobia salmositica. Clinical signs of the disease in salmon (Oncorhynchusspp.) include exophthalmia, general oedema, abdominal distension with ascites, anaemia, and anorexia. The disease-causing factor is a metalloprotease and the monoclonal antibody (mAb-001) against it is therapeutic. MAb-001 does not fix complement but agglutinates the parasite. Some brook charr,Salvelinus fontinaliscannot be infected (Cryptobia-resistant); this resistance is controlled by a dominant Mendelian locus and is inherited. InCryptobia-resistant charr the pathogen is lysed via the Alternative Pathway of Complement Activation. However, some charr can be infected and they have high parasitaemias with no disease (Cryptobia-tolerant). In infectedCryptobia-tolerant charr the metalloprotease is neutralized by a natural antiprotease,α2 macroglobulin. Two vaccines have been developed. A single dose of the attenuated vaccine protects 100% of salmonids (juveniles and adults) for at least 24 months. Complement fixing antibody production and cell-mediated response in vaccinated fish rise significantly after challenge. Fish injected with the DNA vaccine initially have slight anaemias but they recover and have agglutinating antibodies. On challenge, DNA-vaccinated fish have lower parasitaemias, delayed peak parasitaemias and faster recoveries. Isometamidium chloride is therapeutic against the pathogen and its effectiveness is increased after conjugation to antibodies.

scholarly journals Molecular basis of the enhanced susceptibility of the erythrocytes of paroxysmal nocturnal hemoglobinuria to hemolysis in acidified serum

Blood ◽  
1991 ◽  
Vol 78 (3) ◽  
pp. 820-829 ◽  
Author(s):  
LA Wilcox ◽  
JL Ezzell ◽  
NJ Bernshaw ◽  
CJ Parker
Keyword(s):  
Paroxysmal Nocturnal Hemoglobinuria ◽  
Alternative Pathway ◽  
Regulatory Protein ◽  
Membrane Attack Complex ◽  
Factor H ◽  
Alternative Pathways ◽  
Complement Control Protein ◽  
Alternative Pathway Of Complement ◽  
Regulatory Effects ◽  
And Control

When incubated in acidified serum, the erythrocytes of paroxysmal nocturnal hemoglobinuria (PNH) are hemolyzed through activation of the alternative pathway of complement (APC), but normal erythrocytes are resistant to this process. PNH cells are deficient in decay- accelerating factor (DAF), a complement regulatory protein that inhibits the activity of both the classical and the alternative pathways. However, deficiency of DAF alone does not account entirely for the aberrant effects of acidified serum on PNH cells. Recently, we have shown that PNH erythrocytes are also deficient in another complement control protein called membrane inhibitor of reactive lysis (MIRL) that restricts complement-mediated lysis by blocking formation of the membrane attack complex (MAC). To determine the effects of the DAF and MIRL on susceptibility to acidified serum lysis, PNH cells were repleted with the purified proteins. DAF partially inhibited acidified serum lysis by blocking the activity of the amplification C3 convertase. MIRL inhibited acidified serum lysis both by blocking the activity of the MAC and by inhibiting the activity the C3 convertase. When DAF function was blocked with antibody, normal erythrocytes became partially susceptible to acidified serum lysis. By blocking MIRL, cells were made completely susceptible to lysis, and control of C3 convertase activity was partially lost. When both DAF and MIRL were blocked, the capacity of normal erythrocytes to control the activity of the APC and the MAC was destroyed, and the cells hemolyzed even in unacidified serum. These studies demonstrate that DAF and MIRL act in concert to control susceptibility to acidified serum lysis; of the two proteins, MIRL is the more important. In addition to its regulatory effects on the MAC, MIRL also influences the activity of the C3 convertase of the APC. Further, in the absence of DAF and MIRL, the plasma regulators (factor H and factor I) lack the capacity to control membrane- associated activation of the APC.

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