The polymorphisms C807T and G873A of the platelet integrin 2β1 (collagen receptor glycoprotein [GP] Ia-IIa) are linked to the expression density of this receptor. The GPIa T807/A873 allele causes a higher receptor expression, enhancing... more
The polymorphisms C807T and G873A of the platelet integrin 2β1 (collagen receptor glycoprotein [GP] Ia-IIa) are linked to the expression density of this receptor. The GPIa T807/A873 allele causes a higher receptor expression, enhancing platelet binding to collagen. This might present a genetic predisposition for the development of thromboembolic complications. In this case-control study, the genotypes of the GPIa C807T polymorphism and presence of conventional risk factors (hypertension, diabetes mellitus, and smoking) were compared in stroke patients and patients without cerebrovascular disease (non-CVD patients) ≤50 years of age (n = 45 and 41, respectively) and in stroke patients and non-CVD patients more than 50 years of age (n = 182 and 129, respectively. In patients ≤50 years of age, the T807 allele was the only overrepresented variable (P = .023; odds ratio, 3.02; 95% confidence interval, 1.20 to 7.61) and an independent risk factor, whereas the presence of conventional risk...
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Research Interests: Immunology, Evidence Based Medicine, Clinical Trial, Medicine, Platelet, and 11 moreHumans, Consensus, Thrombocytopenia, Monoclonal Antibodies, Haemostasis and Thrombosis, Clinical Sciences, Autoantibodies, Immune thrombocytopenia, Clinical Trials as Topic, Blood platelets, and Cardiovascular medicine and haematology
The CD11b/CD18 integrin plays a crucial role in cell-cell adhesion processes. Recently, we described a case of severe neonatal alloimmune neutropenia (NAIN) caused by an alloantibody against a variant of the CD11b subunit (Mart... more
The CD11b/CD18 integrin plays a crucial role in cell-cell adhesion processes. Recently, we described a case of severe neonatal alloimmune neutropenia (NAIN) caused by an alloantibody against a variant of the CD11b subunit (Mart alloantigen). Allele-specific transfected cells allowed us to demonstrate that an H61R point mutation is directly responsible for the formation of Mart epitopes. No difference in the adhesion capability between H61 and R61 homozygous neutrophils was observed. Functional analysis showed that anti-Mart inhibited Mac-1–dependent adhesion of neutrophils and monocytic U937 cells to fibrinogen, intercellular adhesion molecule-1 (ICAM-1), receptor for advanced glycation end product (RAGE), and glycoprotein Ibα but not to junctional adhesion molecule-C or urokinase plasminogen activator receptor (uPAR). Accordingly, anti-Mart blocked neutrophil and U937 cell adhesion to endothelial cells and platelet-leukocyte aggregate formation in whole blood under high shear. Othe...
Research Interests: Chemistry, Flow Cytometry, Cell Adhesion, Medicine, Cercopithecus aethiops, and 15 moreHumans, Animals, Blood, Polymerase Chain Reaction, CD, Clinical Sciences, Neutrophils, Genotype, Transfection, Base Sequence, Integrin, Blood platelets, Gene frequency, Cardiovascular medicine and haematology, and Paediatrics and reproductive medicine
Research Interests: Biochemistry, Chemistry, Molecular Biology, Biological Chemistry, Medicine, and 15 moreBiological Sciences, DNA, Platelet, Humans, Animals, Biological, Glycosylation, CHEMICAL SCIENCES, Cysteine, Amino Acid Sequence, Base Sequence, Molecular Sequence Data, Blood platelets, Gene frequency, and Medical and Health Sciences
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While interleukin (IL)-1β is a potent pro-inflammatory cytokine involved in host defense, high levels can cause life-threatening sterile inflammation including systemic inflammatory response syndrome. Hence, the control of IL-1β secretion... more
While interleukin (IL)-1β is a potent pro-inflammatory cytokine involved in host defense, high levels can cause life-threatening sterile inflammation including systemic inflammatory response syndrome. Hence, the control of IL-1β secretion is of outstanding biomedical importance. In response to a first inflammatory stimulus such as lipopolysaccharide, pro-IL-1β is synthesized as a cytoplasmic inactive pro-form. Extracellular ATP originating from injured cells is a prototypical second signal for inflammasome-dependent maturation and release of IL-1β. The human anti-protease alpha-1 antitrypsin (AAT) and IL-1β regulate each other mechanisms that are only partially understood. Here, we demonstrate that physiological concentrations of AAT efficiently inhibit ATP-induced release of IL-1β from primary human blood mononuclear cells, monocytic U937 cells, and rat lung tissue, whereas ATP-independent IL-1β release is not impaired. Both, native and oxidized AAT are active, suggesting that the ...
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The Fcγ receptor IIIb (FcγRIIIb) for the Fc domain of IgG is expressed exclusively on neutrophils. The FcγRIIIb bears allotypic polymorphisms referred to as NA1, NA2, and SH, which are known for their frequent involvement in alloimmune... more
The Fcγ receptor IIIb (FcγRIIIb) for the Fc domain of IgG is expressed exclusively on neutrophils. The FcγRIIIb bears allotypic polymorphisms referred to as NA1, NA2, and SH, which are known for their frequent involvement in alloimmune and autoimmune neutropenias as well as in transfusion reactions. The bactericidal capacity of isolated neutrophils is easily activatable, and activation results in self-desintegration, thus preventing storage of neutrophils. As a result, only freshly isolated granulocytes can be used for antibody screening, often making it impossible to use typed panel cells. To provide a readily available source of typed panel cells, we therefore established stable mammalian cells expressing recombinant NA1, NA2, and SH antigens. We isolated mRNA from typed neutrophils and then transcribed it in cDNA. The cDNA that codes for the different forms of the FcγRIIIb was amplified by polymerase chain reaction and was subsequently subcloned into the mammalian expression vect...
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Fetal/neonatal alloimmune thrombocytopenia is a severe bleeding disorder, which can result in intracranial hemorrhage (ICH), leading to death or neurological sequelae. In whites, maternal anti-human platelet antigen-1a (HPA-1a) antibodies... more
Fetal/neonatal alloimmune thrombocytopenia is a severe bleeding disorder, which can result in intracranial hemorrhage (ICH), leading to death or neurological sequelae. In whites, maternal anti-human platelet antigen-1a (HPA-1a) antibodies are responsible for the majority of cases. No predictive factors for ICH are available to guide prophylactic treatment during pregnancy. In this study, we investigated antibodies from mothers with ICH-positive fetal/neonatal alloimmune thrombocytopenia and with ICH-negative fetal/neonatal alloimmune thrombocytopenia to identify serological and functional differences between the groups. In an antigen capture assay, we observed a stronger binding of +ICH antibodies to endothelial cell (EC)-derived αvβ3. By absorption experiments, we subsequently identified anti-HPA-1a antibodies of anti-αvβ3 specificity in the +ICH but not in the -ICH cohort. Only the anti-αvβ3 subtype, but not the anti-β3 subtype, induced EC apoptosis of HPA-1a-positive ECs by caspa...
Research Interests: Immunology, Cell Adhesion, Apoptosis, Humans, Endothelial Cells, and 15 moreFemale, Animals, Male, Clinical Sciences, Caspase, Antibody, Fetus, Gestational Age, Antigen, Autoantibodies, Case Control Studies, CHO cells, Cardiovascular medicine and haematology, Human Umbilical Vein Endothelial Cells, and Intracranial hemorrhages
Objective— In contrast to other antibodies involved in transfusion-related acute lung injury, anti–HNA-3a antibodies are incapable of inducing direct neutrophil activation and seem to interact with endothelial cells (ECs) primarily. In... more
Objective— In contrast to other antibodies involved in transfusion-related acute lung injury, anti–HNA-3a antibodies are incapable of inducing direct neutrophil activation and seem to interact with endothelial cells (ECs) primarily. In animal studies, anti–HNA-3a-mediated transfusion-related acute lung injury could be precipitated in the absence of neutrophils, but was stronger when neutrophils were present. In a different context the target protein of these antibodies, choline transporter-like protein-2 (CTL-2), was reported to interact with a protein of the inner ear carrying 2 von Willebrand factor (VWF) A-domains. These observations prompted us to investigate whether VWF might be involved in anti–HNA-3a-mediated neutrophil activation, and whether signaling via CD11b/CD18 is involved, as in various other experimental settings. Approach and Results— Cell adhesion demonstrated specific binding of CTL-2 to VWF. Immunoprecipitation analysis of CTL-2/CD11b/CD18 coexpressing cells indi...
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SummaryNeonatal alloimmune thrombocytopenia (NAIT) is caused by fetomaternal platelet incompatibility with maternal antibodies crossing the placenta and destroying fetal platelets. Antibodies against human platelet antigen-1a (HPA-1a) and... more
SummaryNeonatal alloimmune thrombocytopenia (NAIT) is caused by fetomaternal platelet incompatibility with maternal antibodies crossing the placenta and destroying fetal platelets. Antibodies against human platelet antigen-1a (HPA-1a) and HPA-5b are responsible for the majority of NAIT cases. We observed a suspected NAIT in a newborn with a platelet count of 25 G/l and petechial haemorrhages. Serological analysis of maternal serum revealed an immunisation against αIIbβ3 on paternal platelets only, indicating the presence of an antibody against a new rare alloantigen (Seca) residing on αIIbβ3. The location of Seca on αIIbβ3 was confirmed by immunoprecipitation. Nucleotide sequence analysis of paternal β3 revealed a single nucleotide exchange (G1818T) in exon 11 of the β3 gene (ITGB3), changing Lys580 (wild-type) to Asn580 (Seca). Two additional members of the family Sec were typed Seca positive, but none of 300 blood donors. Chinese hamster ovary cells expressing Asn580, but not Lys5...
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Junctional adhesion molecule (JAM)-C is an Ig superfamily protein, which is involved in the regulation of various inflammatory and vascular events such as transendothelial leukocyte migration. JAM-C is expressed highly on the surface of... more
Junctional adhesion molecule (JAM)-C is an Ig superfamily protein, which is involved in the regulation of various inflammatory and vascular events such as transendothelial leukocyte migration. JAM-C is expressed highly on the surface of endothelial cells and platelets, whereas expression in T lymphocytes is not well studied. To investigate the specific gene regulation of JAM-C in T lymphocytes, we determined JAM-C expression in quiescent and activated human T cells. Treatment with the polyclonal T cell activator PHA increased surface and total JAM-C expression in T cells time- and dose-dependently, as determined by flow cytometry and immunoblot analysis. In contrast, no up-regulation of JAM-A in activated T cells was detectable. The highest level of JAM-C up-regulation by PHA was observed in CD3+forkhead box P3+ and CD4+CD25high T cells. Moreover, TCR activation with combined anti-CD3 and anti-CD28 stimulation induced JAM-C expression in T cells. JAM-C induction occurred at the mRNA...
Research Interests: Immunology, Molecular Biology, Gene regulation, Biology, Cell Biology, and 15 moreMedicine, Gene expression, Signal Transduction, Humans, T Cell, CD, T lymphocytes, Molecular cloning, Calcineurin, NFAT, Base Sequence, Junctional adhesion molecule, Gene Expression Regulation, Cell Adhesion Molecules, and Molecular Sequence Data
Research Interests: Immunology, Cell Trafficking, Inflammation, Membrane Proteins, Medicine, and 15 moreAntibodies, Animals, Clinical Sciences, In Vivo, Contact Dermatitis, Endothelial cell, Enzyme activity, INVESTIGATIVE, Junctional adhesion molecule, Leukocytes, Immunoglobulins, Cell Adhesion Molecules, Allergic Contact Dermatitis, Extravasation, and hematoxylin and eosin
The human neutrophil-specific adhesion molecule CD177 (also known as the NB1 alloantigen) becomes upregulated on the cell surface in a number of inflammatory settings. We recently showed that CD177 functions as a novel heterophilic... more
The human neutrophil-specific adhesion molecule CD177 (also known as the NB1 alloantigen) becomes upregulated on the cell surface in a number of inflammatory settings. We recently showed that CD177 functions as a novel heterophilic counterreceptor for the endothelial junctional protein PECAM-1 (CD31), an interaction that is mediated by membrane-proximal PECAM-1 IgD 6, which is known to harbor an S536N single nucleotide polymorphism of two major isoforms V98N536G643 and L98S536R643 and a yet-to-be-determined region on CD177. In vitro transendothelial migration experiments revealed that CD177+ neutrophils migrated significantly faster through HUVECs expressing the LSR, compared with the VNG, allelic variant of PECAM-1 and that this correlated with the decreased ability of anti-PECAM-1 Ab of ITIM tyrosine phosphorylation in HUVECs expressing the LSR allelic variant relative to the VNG allelic variant. Moreover, engagement of PECAM-1 with rCD177-Fc (to mimic heterophilic CD177 binding) ...
Research Interests: Immunology, Flow Cytometry, Biology, Cell Biology, Immunology of the Gut, and 15 moreMedicine, Cell separation, Humans, Endothelial Cells, Surface plasmon resonance, Phosphorylation, CD, Neutrophils, Single Nucleotide Polymorphism, Protein isoforms, Base Sequence, Tyrosine Phosphorylation, Immunoblotting, Molecular Sequence Data, and reverse transcriptase polymerase chain reaction
The recently described junctional adhesion molecules (JAMs) in man and mice are involved in homotypic and heterotypic intercellular interactions. Here, a third member of this family, human JAM-3, was identified and described as a novel... more
The recently described junctional adhesion molecules (JAMs) in man and mice are involved in homotypic and heterotypic intercellular interactions. Here, a third member of this family, human JAM-3, was identified and described as a novel counterreceptor on platelets for the leukocyte β2-integrin Mac-1 (αMβ2, CD11b/CD18). With the help of two monoclonal antibodies, Gi11 and Gi13, against a 43-kD surface glycoprotein on human platelets, a full-length cDNA encoding JAM-3 was identified. JAM-3 is a type I transmembrane glycoprotein containing two Ig-like domains. Although JAM-3 did not undergo homophilic interactions, myelo-monocytic cells adhered to immobilized JAM-3 or to JAM-3–transfected cells. This heterophilic interaction was specifically attributed to a direct interaction of JAM-3 with the β2-integrin Mac-1 and to a lower extent with p150.95 (αXβ2, CD11c/CD18) but not with LFA-1 (αLβ2, CD11a/CD18) or with β1-integrins. These results were corroborated by analysis of K562 erythroleuk...
Research Interests: Cell Adhesion, Cell Biology, Humans, Mice, Animals, and 15 moreArticle, CD, Experimental Medicine, Amino Acid Sequence, Base Sequence, Junctional adhesion molecule, Leukocytes, Integrin, Cell Adhesion Molecules, Molecular Sequence Data, CHO cells, Blood platelets, Cricetinae, Medical and Health Sciences, and In Vitro Techniques
Research Interests: Molecular Biology, Polymorphism, Biology, Cell Adhesion, Medicine, and 14 morePlatelet, Humans, Polymerase Chain Reaction, P-glycoprotein, Genetic Polymorphism, Amino Acid Profile, Sialic Acid, Base Sequence, Clinical Investigation, Integrin, Molecular Sequence Data, Blood platelets, epitope, and Medical and Health Sciences
Research Interests: Chemistry, Biology, Biological Chemistry, Medicine, Biological Sciences, and 13 moreCell line, Humans, Animals, Biological, Membrane, CHEMICAL SCIENCES, Protein Secondary Structure Prediction, Hylobates, Receptor, Species Specificity, Protein Binding, Granulomatosis with polyangiitis, and Medical and Health Sciences
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Research Interests: Chemistry, Flow Cytometry, Cell Adhesion, Cell Biology, Biological Chemistry, and 15 moreMedicine, Biological Sciences, Humans, Animals, Monoclonal Antibodies, CHEMICAL SCIENCES, Cell communication, Epitopes, Leukocytes, Enzyme Linked Immunosorbent Assay, binding sites, CHO cells, Blood platelets, Cricetinae, and Medical and Health Sciences
Research Interests: Chemistry, Flow Cytometry, Biology, Inflammation, Cell Adhesion, and 15 moreCell Biology, Biological Chemistry, Adhesion, Biological Sciences, In Vitro, Humans, Endothelial Cells, Animals, Biological, CHEMICAL SCIENCES, In Vivo, Immunoglobulins, Cell Adhesion Molecules, Immunoblotting, and In Vitro Techniques
Research Interests: Chemistry, Immunology, Cell Adhesion, Medicine, Adhesion, and 15 moreEndothelial Cells, Mice, Animals, Male, Vascular endothelium, T lymphocytes, ENDOTHELIUM, Immune Tolerance, Junctional adhesion molecule, Immunoglobulins, Intravital Microscopy, Integrin, Cell Adhesion Molecules, Adoptive Transfer, and Paediatrics and reproductive medicine
Hematogenous dissemination of melanoma is a life-threatening complication of this malignant tumor. Here, we identified junctional adhesion molecule-C (JAM-C) as a novel player in melanoma metastasis to the lung. JAM-C expression was... more
Hematogenous dissemination of melanoma is a life-threatening complication of this malignant tumor. Here, we identified junctional adhesion molecule-C (JAM-C) as a novel player in melanoma metastasis to the lung. JAM-C expression was identified in human and murine melanoma cell lines, in human malignant melanoma, as well as in metastatic melanoma including melanoma lung metastasis. JAM-C expressed on both murine B16 melanoma cells as well as on endothelial cells promoted the transendothelial migration of the melanoma cells. We generated mice with inactivation of JAM-C. JAM-C−/− mice as well as endothelial-specific JAM-C–deficient mice displayed significantly decreased B16 melanoma cell metastasis to the lung, whereas treatment of mice with soluble JAM-C prevented melanoma lung metastasis. Together, JAM-C represents a novel therapeutic target for melanoma metastasis. Cancer Res; 71(12); 4096–105. ©2011 AACR.
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Transfusion-related acute lung injury (TRALI) is the leading cause of transfusion-associated mortality in the United States and other countries. In most TRALI cases, human leukocyte antigen (HLA) class II antibodies are detected in... more
Transfusion-related acute lung injury (TRALI) is the leading cause of transfusion-associated mortality in the United States and other countries. In most TRALI cases, human leukocyte antigen (HLA) class II antibodies are detected in implicated donors. However, the corresponding antigens are not present on the cellular key players in TRALI: neutrophils and endothelium. In this study, we identify monocytes as a primary target in HLA class II–induced TRALI. Monocytes become activated when incubated with matched HLA class II antibodies and are capable of activating neutrophils, which, in turn, can induce disturbance of an endothelial barrier. In an ex vivo rodent model, HLA class II antibody–dependent monocyte activation leads to severe pulmonary edema in a relevant period of time, whenever neutrophils are present and the endothelium is preactivated. Our data suggest that in most TRALI cases, monocytes are cellular key players, because HLA class II antibodies induce TRALI by a reaction c...
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Key PointsThe study describes a potential novel treatment of fetal alloimmune thrombocytopenia by dissecting the effector activities of an epitope-specific IgG antibody. Neither the in vivo transplacental transport nor the inhibiting... more
Key PointsThe study describes a potential novel treatment of fetal alloimmune thrombocytopenia by dissecting the effector activities of an epitope-specific IgG antibody. Neither the in vivo transplacental transport nor the inhibiting properties of the blocking antibody are impaired by the N-glycan modification.
Research Interests: Chemistry, Biology, Medicine, Humans, Placenta, and 15 moreMice, Female, Animals, Blood, Monoclonal Antibodies, Glycosylation, Clinical Sciences, Antibody, Phagocytosis, Monoclonal Antibody, Molecular Targeted Therapy, Blood platelets, epitope, Cardiovascular medicine and haematology, and Paediatrics and reproductive medicine
Objective— Antibodies against human neutrophil antigen-3a (HNA-3a) located on choline transporter-like protein 2 induce severe transfusion-related acute lung injury (TRALI). This study aims to identify the mechanism implicated in... more
Objective— Antibodies against human neutrophil antigen-3a (HNA-3a) located on choline transporter-like protein 2 induce severe transfusion-related acute lung injury (TRALI). This study aims to identify the mechanism implicated in anti–HNA-3a-mediated TRALI. Approach and Results— Our analysis shows that anti–HNA-3a recognizes 2 choline transporter-like protein 2 isoforms (P1 and P2) on human microvascular endothelial cells from lung blood vessels but reacts only with the P1 isoform on neutrophils. Direct treatment of HNA-3a–positive endothelial cells with anti–HNA-3a, but not with anti–HNA-3b, leads to reactive oxygen species production, increased albumin influx, and decreased endothelial resistance associated with the formation of actin stress filaments and loosening of junctional vascular endothelium-cadherin. In a novel in vivo mouse model, TRALI was documented by significant increase in lung water content, albumin concentration, and neutrophil numbers in the bronchoalveolar lavag...
Research Interests: Biology, Medicine, Antibodies, Humans, Mice, and 14 moreAnimals, Vascular endothelium, Acute Lung Injury, Lung, Membrane transport proteins, NADPH oxidase, Clinical Sciences, Neutrophils, In Vivo, Lipopolysaccharides, Blood Transfusion, ENDOTHELIUM, Transfusion Related Acute Lung Injury, and Cardiovascular medicine and haematology
Objective— Thrombotic events and immunoinflammatory processes take place next to each other during vascular remodeling in atherosclerotic lesions. In this study we investigated the interaction of platelets with dendritic cells (DCs).... more
Objective— Thrombotic events and immunoinflammatory processes take place next to each other during vascular remodeling in atherosclerotic lesions. In this study we investigated the interaction of platelets with dendritic cells (DCs). Methods and Results— The rolling of DCs on platelets was mediated by PSGL-1. Firm adhesion of DCs was mediated through integrin α M β 2 (Mac-1). In vivo, adhesion of DCs to injured carotid arteries in mice was mediated by platelets. Pretreatment with soluble GPVI, which inhibits platelet adhesion to collagen, substantially reduced recruitment of DCs to the injured vessel wall. In addition, preincubation of DCs with sJAM-C significantly reduced their adhesion to platelets. Coincubation of DCs with platelets induced maturation of DCs, as shown by enhanced expression of CD83. In the presence of platelets, DC-induced lymphocyte proliferation was significantly enhanced. Moreover, coincubation of DCs with platelets resulted in platelet phagocytosis by DCs, as...
Research Interests: Chemistry, Cell Trafficking, Biology, Cell Adhesion, Cell Biology, and 15 moreApoptosis, Adhesion, Dendritic Cells, Cell Differentiation, Humans, Animals, Dendritic cell, Clinical Sciences, Cell communication, Adhesion molecules, Lymphocytes, Carotid Artery, Cell Adhesion Molecules, Blood platelets, and Cardiovascular medicine and haematology
Objective— Glycoprotein (GP) Ibα is the functionally dominant subunit of the platelet GPIb-IX-V receptor complex. The N-terminal domain of the GPIbα chain contains binding sites for α-thrombin and von Willebrand factor (VWF). The human... more
Objective— Glycoprotein (GP) Ibα is the functionally dominant subunit of the platelet GPIb-IX-V receptor complex. The N-terminal domain of the GPIbα chain contains binding sites for α-thrombin and von Willebrand factor (VWF). The human platelet alloantigen (HPA)-2 polymorphism of the GPIbα gene is associated with a C/T transition at nucleotide 1018, resulting in a Thr/Met dimorphism at residue 145 of GPIbα. To study the structural and functional effects of this dimorphism, N-terminal fragments (AA1-289) of the HPA-2a and HPA-2b alloform of GPIbα expressed in CHO cells were used. Methods and Results— Of 74 moAbs directed against human GPIbα, 2 antibodies with epitope between AA1-59 could differentiate between both alloforms. In addition, VWF bound with a higher affinity to the recombinant HPA-2a fragment or to homozygous HPA-2a platelets. In contrast, no difference was found in the binding of α-thrombin to the recombinant alloform fragments or of antibodies directed against the α-thr...
Research Interests: Molecular Biology, Polymorphism, Biology, Vascular biology, Platelet, and 13 moreThrombin, von Willebrand factor, Animals, P-glycoprotein, Clinical Sciences, Recombinant DNA, Genetic Polymorphism, Recombinant Proteins, CHO cells, Blood platelets, Cricetinae, epitope, and Cardiovascular medicine and haematology
We recently described a new low-frequency platelet alloantigen on the human platelet glycoprotein (GP) Ib-IX complex, termed Iya, which was implicated in a severe case of neonatal alloimmune thrombocytopenia. Immunoprecipitation studies... more
We recently described a new low-frequency platelet alloantigen on the human platelet glycoprotein (GP) Ib-IX complex, termed Iya, which was implicated in a severe case of neonatal alloimmune thrombocytopenia. Immunoprecipitation studies with trypsin-treated platelets indicated that the Iyaalloantigenic determinants are formed by the membrane-associated remnant moiety of GP Ib (GP Ibr) together with GP Ibβ and GP IX. To elucidate the molecular basis underlying the Iya alloantigen, we amplifiedGPIbr, GPIbβ, andGPIX genes by polymerase chain reaction (PCR). Nucleotide-sequence analysis of these 3 genes showed a G to A transition at position 141 on GPIbβ gene in a subject positive for Iya. This transition resulted in a Gly15Glu dimorphism on the N-terminal domain ofGPIbβ. This finding was confirmed by genotyping analysis of 6 Iya-positive subjects by restriction fragment length polymorphism (RFLP) studies using NarI endonuclease. In 300 randomly selected healthy blood donors, one Iya...
Research Interests: Molecular Biology, Biology, Platelet, Humans, Autoimmune diseases, and 15 moreAnimals, Blood, Polymerase Chain Reaction, Thrombocytopenia, Pedigree, Phenotype, Clinical Sciences, Newborn Infant, Amino Acid Substitution Rates, Epitopes, DNA mutational analysis, CHO cells, Cricetinae, Cardiovascular medicine and haematology, and Paediatrics and reproductive medicine
The molecular details of leukocyte transmigration through the endothelial barrier (also called diapedesis), which is the final step of leukocyte extravasation from the circulation to a given site of inflammation, are by far not well... more
The molecular details of leukocyte transmigration through the endothelial barrier (also called diapedesis), which is the final step of leukocyte extravasation from the circulation to a given site of inflammation, are by far not well understood. The present review will focus on the different mechanisms potentially involved in leukocyte trans-endothelial migration. Both homophilic and heterophilic interactions between leukocyte and endothelial cell receptors will be covered, with a particular focus on the growing gene family of junctional adhesion molecules (JAM). Deciphering their mechanisms of interaction will also allow to unravel novel strategies for therapeutic intervention in inflammatory or atherothrombotic diseases.
Research Interests: Immunology, Inflammation, Membrane Proteins, Cell Biology, Medicine, and 11 moreHumans, Animals, Vascular endothelium, Haemostasis and Thrombosis, Clinical Sciences, Leukocytes, Immunoglobulins, Leukocyte trafficking, Cell Adhesion Molecules, Extravasation, and Cardiovascular medicine and haematology
This review updates our present state of knowledge with regard to platelet-specific alloantigens, i.e. Zwa/Zwb (PlAl/PlA2), Baka/Bakb, Koa/Kob, Yuka/Yukb (Penb/Pena), Bra/Brb, Nak, Sib, and summarizes relevant immunogenetical and... more
This review updates our present state of knowledge with regard to platelet-specific alloantigens, i.e. Zwa/Zwb (PlAl/PlA2), Baka/Bakb, Koa/Kob, Yuka/Yukb (Penb/Pena), Bra/Brb, Nak, Sib, and summarizes relevant immunogenetical and biochemical data. The impact of corresponding platelet-specific antibodies in clinical conditions such as neonatal alloimmune thrombocytopenia, posttransfusion purpura, and the refractory state of platelet transfusions is reviewed with particular emphasis on our own case material.
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Fetal and neonatal alloimmune thrombocytopenia (FNAIT) is a bleeding disorder caused by transplacental passage of maternal antibodies to fetuses whose platelets (PLTs) express the corresponding human PLT antigen (HPA). We observed a fetus... more
Fetal and neonatal alloimmune thrombocytopenia (FNAIT) is a bleeding disorder caused by transplacental passage of maternal antibodies to fetuses whose platelets (PLTs) express the corresponding human PLT antigen (HPA). We observed a fetus with FNAIT who died from a severe intracranial hemorrhage. Analysis of maternal serum in antigen capture assay with paternal PLTs showed reactivity with PLT glycoprotein (GP)IIb/IIIa (α(IIb) β(3) ) and GPIa/IIa (α(2) β(1) integrin), indicating the presence of anti-HPA-1a and an additional alloantibody against GPIa (termed anti-Swi(a) ). By immunochemical studies, the localization of the Swi(a) antigen on GPIa/IIa could be confirmed. Analysis of paternal GPIa full-length cDNA showed a single-nucleotide substitution C(3347) T in Exon 28 resulting in a Thr(1087) Met amino acid substitution. Testing of family members by polymerase chain reaction-restriction fragment length polymorphism using MslI endonuclease showed perfect correlation with phenotyping...
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Human platelet and neutrophil antigens (HPAs, HNAs) are targets for platelet or granulocyte antibodies causing immune thrombocytopenia or neutropenia, respectively. Currently, genotyping is replacing phenotyping as the preferred method of... more
Human platelet and neutrophil antigens (HPAs, HNAs) are targets for platelet or granulocyte antibodies causing immune thrombocytopenia or neutropenia, respectively. Currently, genotyping is replacing phenotyping as the preferred method of diagnosis of immune cytopenia. To establish a reliable genotyping analysis, however, the availability as reference DNA of genomic DNA from persons of known genotype is essential. By the use of Epstein-Barr virus transformation, panels of B-lympho-blastoid cell lines (B-LCLs) from HPA- and HNA-phenotyped individuals were developed. Genomic DNA was isolated from these cell lines and tested as reference DNA for genotyping of persons for HPAs and HNAs. DNA derived from these B-LCLs was typed by polymerase chain reaction-restriction fragment length polymorphism and -sequence-specific primers. The results were in accordance with the genotyping from peripheral blood cells. These results were confirmed by 24 laboratories in Germany in a blind study. The inexhaustible source of reference DNA derived from B-LCLs allowed the evaluation of reliable HPA and HNA genotyping for quality control purposes. It should facilitate the development of DNA typing in blood centers and clinical laboratories.
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Research Interests: Nanoparticles, Medicine, Antibodies, Humans, Heparin, and 11 moreBlood, Thrombocytopenia, Haemostasis and Thrombosis, Clinical Sciences, Time Factors, Cost Benefit Analysis, Immunoassay, Sensitivity and Specificity, Predictive value of tests, Cardiovascular medicine and haematology, and Paediatrics and reproductive medicine
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We recently reported that junctional adhesion molecule (JAM)-C plays a role in leukocyte transendothelial migration. Here, the role of JAM-C in vascular permeability was investigated in vitro and in vivo. As opposed to macrovascular... more
We recently reported that junctional adhesion molecule (JAM)-C plays a role in leukocyte transendothelial migration. Here, the role of JAM-C in vascular permeability was investigated in vitro and in vivo. As opposed to macrovascular endothelial cells that constitutively expressed JAM-C in cell–cell contacts, in quiescent microvascular endothelial cells, JAM-C localized mainly intracellularly, and was recruited to junctions upon short-term stimulation with vascular endothelial growth factor (VEGF) or histamine. Strikingly, disruption of JAM-C function decreased basal permeability and prevented the VEGF- and histamine-induced increases in human dermal microvascular endothelial cell permeability in vitro and skin permeability in mice. Permeability increases are essential in angiogenesis, and JAM-C blockade reduced hyperpermeability and neovascularization in hypoxia-induced retinal angiogenesis in mice. The underlying mechanisms of the JAM-C–mediated increase in endothelial permeability...