G Bein

Justus-Liebig-Universität Gießen, Gieben, Hesse, Germany

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Publications (155)511.09 Total impact

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    ABSTRACT: Extracorporeal photopheresis (ECP) is an important cell-based therapy for graft-versus-host disease (GVHD); however, the blood volume required per treatment to achieve a clinical response is unknown. We developed a mini-ECP technique (mini-ECP) using only 100 to 200 mL of whole blood for patients with contraindications for apheresis or low body weight. Sixteen patients (n = 13 acute, n = 3 chronic GVHD) with a median body weight of 19 kg (range, 7-48 kg) received 460 mini-ECP treatments with a median duration of 115 days (range, 49-973 days). Mini-ECP was well tolerated, and acute GVHD resolved completely in nine of 13 patients and partially in two patients but not in two patients. Cutaneous chronic GVHD exhibited a mixed response (one complete, one partial, and one no response). These results indicate mini-ECP as a novel and less invasive therapy for patients with GVHD and contraindications for apheresis.
    Transfusion 03/2014; · 3.53 Impact Factor
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    ABSTRACT: Immune thrombocytopenia (ITP) is a bleeding disorder caused by IgG autoantibodies (AAbs) directed against platelets (PLTs). IgG effector functions depend on their Fc-constant region which undergoes posttranslational glycosylation. We investigated the role of Asn279-linked N-glycan of AAbs in vitro and in vivo. AAbs were purified from ITP patients (n=15) and N-glycans were enzymatically cleaved by endoglycosidase F. The effects of native AAbs and deglycosylated AAbs were compared in vitro on enhancement of phagocytosis of platelets by monocytes and complement fixation and activation applying flow cytometry, laser scanning microscopy, and a complement consumption assay. AAb-induced platelet phagocytosis was inhibited by N-glycan cleavage (median phagocytic activity: 8% vs 0.8%, p=0.004). Seven out of 15 native AAbs bound C1q and activated complement. N-glycan cleavage significantly reduced both effects. In vivo survival of human PLTs was assessed after co-transfusion with native or N-glycan cleaved AAbs in a NOD/SCID mouse model. Injection of AAbs resulted in rapid clearance of human platelets compared to control (platelet clearance after 5h (CL5h)75% vs 30%, p<0.001). AAbs that were able to activate complement induced more pronounced platelet clearance in the presence of complement compared to the clearance in the absence of complement (CL5h 82% vs 62%, p=0.003). AAbs lost their ability to destroy platelets in vivo after deglycosylation (CL5h 42%, p<0.001). N-glycosylation of human ITP AAbs appears to be required for platelet phagocytosis and complement activation, reducing platelet survival in vivo. Posttranslational modification of AAbs may constitute an important determinant for the clinical manifestation of ITP.
    Thrombosis and Haemostasis 09/2013; 110(6). · 5.76 Impact Factor
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    ABSTRACT: Genotyping for red blood cell (RBC), platelet (PLT), and granulocyte antigens is a new tool for clinical pathology, transfusion medicine services, and blood banks. Proficiency in laboratory tests can be established by external quality assessments (EQAs), which are required for clinical application in many health care systems. There are few EQAs for molecular immunohematology. We analyzed the participation and pass rates in an EQA for RBC, PLT, and granulocyte antigens. This EQA was distributed by INSTAND, a large nonprofit provider of proficiency tests, twice per year since Fall 2006 as EQA Number 235 Immunohematology A (molecular diagnostic). The coordinators defined at the outset which alleles are mandatory for detection. The number of participants steadily increased from 51 to 73 per proficiency by Fall 2012. More than 60 institutions utilized this EQA at least once a year. Approximately 80% of them participated in RBC, 68% in PLT, and 22% in granulocyte systems. With the exceptions of RHD (82%) and granulocytes (85%), pass rates exceeded 93%. While the pass rate increased for granulocyte and decreased for the ABO system, the pass rates for the other systems changed little over 6½ years. The INSTAND proficiency test program was regularly used for EQA by many institutions, particularly in Central Europe. While the technical standards and pass rates in the participating laboratories were high, there has been little improvement in pass rates since 2006.
    Transfusion 09/2013; · 3.53 Impact Factor
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    ABSTRACT: Klebsiella pneumoniae is a leading cause of severe hospital-acquired respiratory tract infections and death but little is known regarding the modulation of respiratory dendritic cell (DC) subsets. Plasmacytoid DC (pDC) are specialized type 1 interferon producing cells and considered to be classical mediators of antiviral immunity. By using multiparameter flow cytometry analysis we have analysed the modulation of respiratory DC subsets after intratracheal Klebsiella pneumonia infection. Data indicate that pDCs and MoDC were markedly elevated in the post acute pneumonia phase when compared to mock-infected controls. Analysis of draining mediastinal lymph nodes revealed a rapid increase of activated CD103+ DC, CD11b+ DC and MoDC within 48 h post infection. Lung pDC identification during bacterial pneumonia was confirmed by extended phenotyping for 120G8, mPDCA-1 and Siglec-H expression and by demonstration of high Interferon-alpha producing capacity after cell sorting. Cytokine expression analysis of ex vivo-sorted respiratory DC subpopulations from infected animals revealed elevated Interferon-alpha in pDC, elevated IFN-gamma, IL-4 and IL-13 in CD103+ DC and IL-19 and IL-12p35 in CD11b+ DC subsets in comparison to CD11c+ MHC-class IIlow cells indicating distinct functional roles. Antigen-specific naive CD4+ T cell stimulatory capacity of purified respiratory DC subsets was analysed in a model system with purified ovalbumin T cell receptor transgenic naive CD4+ responder T cells and respiratory DC subsets, pulsed with ovalbumin and matured with Klebsiella pneumoniae lysate. CD103+ DC and CD11b+ DC subsets represented the most potent naive CD4+ T helper cell activators. These results provide novel insight into the activation of respiratory DC subsets during Klebsiella pneumonia infection. The detection of increased respiratory pDC numbers in bacterial pneumonia may indicate possible novel pDC functions with respect to lung repair and regeneration.
    Respiratory research 09/2013; 14(1):91. · 3.64 Impact Factor
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    ABSTRACT: Three different apheresis systems were used in our center for the collection of peripheral blood progenitor cells (PBPCs): COM.TEC (Fresenius Healthcare), COBE Spectra, and Spectra Optia (both from Caridian BCT). We compared 131 autologous and 56 allogeneic apheresis procedures to elucidate feasibility and effectiveness of the different systems. Collection efficiacy varied significantly with lowest results obtained with COBE Spectra. COM.TEC and Spectra Optia produced lower WBC contamination than COBE Spectra, but at the expense of higher product volume and longer apheresis time. High collection efficacy and a low product volume may be favorable characteristics of the Spectra Optia.
    Transfusion and Apheresis Science 07/2013; · 1.23 Impact Factor
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    ABSTRACT: Fetal/neonatal alloimmune thrombocytopenia (FNAIT) is often caused by maternal alloantibodies against the human platelet antigen (HPA)-1a, which opsonize fetal platelets. Subsequent platelet destruction is mediated via the Fc-part of the alloantibodies. The monoclonal antibody SZ21 binds to the HPA-1a-epitope and inhibits binding of maternal alloantibodies. However, it also promotes complement activation and phagocytosis. Deglycosylation of antibodies abrogates the Fc-related effector functions. We modified the N-glycan of SZ21 by Endoglycosidase F. The in vivo transplacental transport of N-glycan modified (NGM)-SZ21 was not impaired. When injected into pregnant mice, both native SZ21 and NGM-SZ21 were transported equally into fetal circulation (8.9% vs. 8.7%, respectively, p=0.58). Neither the binding properties of NGM-SZ21 to HPA-1a in surface plasmon resonance, nor inhibition of anti-HPA-1a-induced platelet phagocytosis were affected by N-glycan modification. NGM-SZ21 prevented platelet destruction induced by maternal anti-HPA-1a antibodies in vivo in a NOD/SCID mouse model (platelet clearance after 5h; 18% vs. 62%, in the presence or absence of NGM-SZ21, respectively, p=0.013). Deglycosylation of SZ21 abrogates Fc effector functions, without interfering with placental transport or the ability to block anti-HPA-1a binding. Humanized, deglycosylated anti-HPA-1a monoclonal antibodies may represent a novel treatment strategy to prevent anti-HPA-1a-mediated platelet destruction in FNAIT.
    Blood 05/2013; · 9.78 Impact Factor
  • Transfusion Medicine 03/2013; · 1.26 Impact Factor
  • Transfusion 03/2013; 53(3):482. · 3.53 Impact Factor
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    ABSTRACT: BACKGROUND: Maternal anti-HPA-1a alloantibodies are responsible for most cases of severe fetal and neonatal alloimmune thrombocytopenia (FNAIT). The presence of HPA-1a alloantibodies in maternal blood alone does not predict the fetal platelet (PLT) count, and the predictivity of antibody titers determined by enzyme immunoassays (EIAs) is debated. In contrast to EIA, surface plasmon resonance (SPR) provides information on antibody-binding properties. STUDY DESIGN AND METHODS: Sequential sera from pregnant women with expected FNAIT were assessed for HPA-1a alloantibodies using SPR. Group I (n = 6) was treated with intravenous immunoglobulin (IVIG) and steroids beginning at 19 weeks of gestation (w.g.), and Group II (n = 4) received intrauterine PLT transfusions (IUT) beginning at 22 w.g. Maternal alloantibodies were quantified using an HPA-1a monoclonal antibody (MoAb) as a standard. Antibody avidity was determined as the ratio of B(700) (end of the dissociation phase) to B(350) (end of the association phase); the area under the curve (AUC) was calculated to determine overall antibody binding. RESULTS: After 22 w.g., alloantibody characteristics remained stable in both groups, while there was a steep decrease in B(700) and B(350) values between 16 and 22 w.g. (assessed only in Group I), indicating a decrease in anti-HPA-1a alloantibody concentrations. Interestingly, the AUCs of the last maternal sample before elective delivery appeared to be correlated with fetal and neonatal PLT counts (p = 0.014 and 0.017, respectively). CONCLUSION: SPR provides quantitative information on HPA-1a alloantibody characteristics in addition to monoclonal antibody-specific immobilization of platelet antigens. SPR results can be calibrated using a MoAb standard and should be further assessed for a potential correlation with fetal PLT count.
    Transfusion 12/2012; · 3.53 Impact Factor
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    ABSTRACT: Mesenchymal stroma cells (MSC) are increasingly recognized for various applications of cell-based therapies such as regenerative medicine or immunomodulatory treatment strategies. Standardized large-scale expansions of MSC under good manufacturing practice (GMP) -compliant conditions avoiding animal derived components are mandatory for further evaluation of these novel therapeutic approaches in clinical trials. We applied a novel automated hollow-fiber cell expansion system (CES) for in vitro expansion of human bone marrow derived MSC employing a GMP-compliant culture medium with human platelet lysate (HPL). Between 8 and 32 ml primary bone marrow aspirate were loaded into the hollow fiber CES and cultured for 15-27 days. 2-58 million MSC were harvested after primary culture. Further GMP-compliant cultivation of second passage MSC for 13 days led to further 10-20 fold enrichment. Viability, surface antigen expression, differentiation capacity and immunosuppressive function of MSC cultured in the hollow fiber CES were in line with standard criteria for MSC definition. We conclude that MSC can be enriched from primary bone marrow aspirate in a GMP-conform manner within a closed hollow fiber bioreactor and maintain their T lymphocyte inhibitory capacity. Standardized and reliable conditions for large scale MSC expansion pave the way for safe applications in humans in different therapeutic approaches.
    Biochemical and Biophysical Research Communications 11/2012; · 2.28 Impact Factor
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    ABSTRACT: Human Vγ9δ2 (Vδ2) T cells represent a unique effector T cell population in humans and primates detecting nonpeptid phosphoantigens, playing an important role in antimicrobial and antitumor immunity. Currently, it is believed that various leukocyte subsets can promote phosphoantigen-driven Vδ2 cell expansion, but the essential cell type required remains elusive. We have used high purity cell sorting to analyze the cellular requirements for (E)-4-hydroxy-3-methyl-but-2-enyl-pyrophosphate (HMBPP)-driven Vδ2 cell expansion. To our knowledge, we show for the first time that primary human MHC-class II(+) cells are indispensable for HMBPP- and isopentenylpyrophosphate-driven Vδ2 cell expansion. In contrast, MHC-class II(-) cells are unable to promote Vδ2 cell expansion. Moreover, purified primary human TCRαβ(+) T cells, CD4(+), or CD8(+) T cells also failed to promote HMBPP-mediated Vδ2 expansion. Depletion of CD4(+)CD25(+) T cells demonstrated that inability of TCRαβ(+) cells to expand Vδ2 cells was not related to the presence of regulatory T cells. Separation of MHC-class II(+) cells into dendritic cells, monocytes, and B cells revealed that dendritic cells were the most potent Vδ2 expanders. Pulsing experiments demonstrated that HMBPP transforms MHC-class II(+) but not negative cells into Vδ2 expanders. MHC-class II-blocking experiments with mAbs and secondary MHC-class II induction on CD4(+) T cells after CD3/CD28 costimulation indicated that MHC-class II is necessary, but not sufficient to promote Vδ2 expansion. Our results provide novel insight into the primary cell-specific requirements for human Vδ2 expansion.
    The Journal of Immunology 10/2012; · 5.52 Impact Factor
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    ABSTRACT: BACKGROUND: Inbred mouse strains are used in different models of respiratory diseases but the variation of critical respiratory leukocyte subpopulations across different strains is unknown. METHODS: By using multiparameter flow cytometry we have quantitated respiratory leukocyte subsets including dendritic cells subpopulations, macrophages, classical T and B cells, natural killer cells, gammadeltaTCR+ T cells and lineage-negative leukocytes in the five most common inbred mouse strains BALB/c, C57BL/6, DBA/2, 129SV and C3H. To minimize confounding environmental factors, age-matched animals were received from the same provider and were housed under identical specific-pathogen-free conditions. RESULTS: Results revealed significant strain differences with respect to respiratory neutrophils (p=0.005; up to 1.4 fold differences versus C57BL/6 mice), eosinophils (p=0.029; up to 2.7 fold), certain dendritic cell subsets (p<=0.0003; up to 3.4 fold), T (p<0.001; up to 1.6 fold) and B lymphocyte subsets (p=0.005; up to 0.4 fold), gammadelta T lymphocytes (p=0.003; up to 1.6 fold), natural killer cells (p<0.0001; up to 0.6 fold) and lineage-negative innate leukocytes (p<=0.007; up to 3.6 fold). In contrast, total respiratory leukocytes, macrophages, total dendritic cells and bronchoalveolar lavage leukocytes did not differ significantly. Stimulation of respiratory leukocytes via Toll-like receptor 4 and 9 as well as CD3/CD28 revealed significant strain differences of TNF-alpha and IL-10 production. CONCLUSION: Our study demonstrates significant strain heterogeneity of respiratory leukocyte subsets that may impact respiratory immunity in different disease models. Additionally, the results may help identification of optimal strains for purification of rare respiratory leukocyte subsets for ex vivo analyses.
    Respiratory research 10/2012; 13(1):94. · 3.64 Impact Factor
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    ABSTRACT: Background and Objectives  The aim of the 15th ISBT Platelet Immunology Workshop was to evaluate the detection of free platelet-reactive autoantibodies from ITP patients by the use of a standardized MAIPA protocol, to compare sensitivity and specificity of antibody detection for anti-HPA-1a and serologically difficult-to-assess antibodies against HPA-3, to identify whether anti-HPA-1a titration results can be compared between laboratories, and to evaluate HPA genotyping methods. Materials and Methods  Workshop materials were shipped from the organizing laboratory in Giessen, Germany. Thirty laboratories from 19 countries participated. Results  Results for the detection of autoantibodies differed greatly between the laboratories and no consensus was reached for one of the two sera. Detection and titration of antibodies against HPA-1a, in contrast, gave largely congruent results. Serologically difficult-to-assess antibodies recognizing HPA-3a and HPA-3b were not detected by many laboratories. For genotyping, good agreement was achieved. Conclusions  Detection of HPA-1a antibodies, titration of anti-HPA-1a, and HPA genotyping are well performed in most participating laboratories. The workshop has identified two specific areas with room and need for improvement: the detection of autoantibodies and the detection of HPA-3 alloantibodies. Recommendations of the Working Party on techniques that can help to overcome these problems are desirable.
    Vox Sanguinis 05/2012; 103(4):343-51. · 2.85 Impact Factor
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    ABSTRACT: BACKGROUND: Several methods exist for the detection of neutrophil antibodies; most of them, however, require fresh neutrophils. In this study, an enzyme-linked immunosorbent assay (ELISA) using recombinant HNA-1 antigens (rHNAs) was developed to detect HNA-1a, -1b, and -1c alloantibodies in serum samples. STUDY DESIGN AND METHODS: Soluble rHNA-1a, -1b, and -1c were isolated from culture supernatant of transfected insect cells. Purified rHNA antigens were immobilized on microtiter wells using antibody against V5-Tag protein. Sera were added, and bound antibodies were detected by enzyme-labeled secondary antibodies. In parallel, monoclonal antibody-immobilized granulocyte antigen (MAIGA) was performed with two different monoclonal antibodies (MoAbs) against FcγRIIIb (3G8 and BW209). RESULTS: Fifteen MAIGA-positive sera containing HNA-1a alloantibodies were tested in ELISA. Thirteen of 15 (86.7%) MAIGA-positive sera captured by MoAbs 3G8 and/or BW209 reacted specifically with rHNA-1a. Four (26.7%) HNA-1a sera showed additional reaction with rHNA-1c. When anti-HNA-1b alloantibodies were analyzed in ELISA, 13 of 15 (86.7%) showed specific positive reaction with rHNA-1b, and 12 of 15 (80.0%) cross-reacted with rHNA-1c. Two HNA-1c sera reacted specifically with rHNA-1c. Immunoprecipitation analysis of all ELISA-negative HNA-1a and -1b sera did not show any specific band indicating false-positive reaction of these sera in MAIGA assay. CONCLUSIONS: These results suggested that rapid ELISA using recombinant neutrophil antigens may provide a valuable method for rapid screening of human alloantibodies against HNA-1a, -1b, and -1c in patients with neutropenia and in blood donors.
    Transfusion 05/2012; · 3.53 Impact Factor
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    ABSTRACT: It is commonly accepted that antibody-mediated removal of platelets represents a major mechanism of platelet destruction in immune thrombocytopenic purpura (ITP). Although complement activation may participate in platelet clearance, frequency and specificity of complement activation have not yet been studied systematically in ITP. We examined blood samples from 240 patients with ITP. Samples were assessed for the presence of free and bound platelet autoantibodies by a standard glycoprotein-specific assay (monoclonal antibody-specific immobilization of platelet antigens). The ability of all sera to fix complement to a panel of human platelets was investigated in a complement fixation (CF) assay. Fixation of C1q to isolated GP IIb/IIIa was assessed by flow cytometry. Glycoprotein-specific autoantibodies were detected as platelet-bound antibodies in 129 (54%) and as additional free antibodies in 26 (11%) and were undetectable in 111 (46%) patients. Assessing these subgroups for CF, 103 (65%), 21 (81%), and 33 (30%) sera gave positive results. If GP IIb/IIIa was absent from the test platelets, 81 (67%) lost their ability to fix complement; if GP Ib/IX was absent, 37 (30%) lost their ability to fix complement. C1q fixation to immunobeads coated with GP IIb/IIIa was observed in 50% of sera containing anti-GP IIb/IIIa antibodies. In a significant number of patients with chronic ITP, platelet autoantibodies are capable of activating the classical complement pathway. CF is even present in ITP sera without detectable autoantibodies, indicating that current techniques for autoantibody detection may be insufficient. The major targets for complement-fixing autoantibodies in ITP are GP IIb/IIIa and GP Ib/IX.
    European Journal Of Haematology 02/2012; 88(2):167-74. · 2.55 Impact Factor
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    ABSTRACT: The TLR7 agonist imiquimod has been used successfully as adjuvant for skin treatment of virus-associated warts and basal cell carcinoma. The effects of skin TLR7 triggering on respiratory leukocyte populations are unknown. In a placebo-controlled experimental animal study we have used multicolour flow cytometry to systematically analyze the modulation of respiratory leukocyte subsets after skin administration of imiquimod. Compared to placebo, skin administration of imiquimod significantly increased respiratory dendritic cells (DC) and natural killer cells, whereas total respiratory leukocyte, alveolar macrophages, classical CD4+ T helper and CD8+ T killer cell numbers were not or only moderately affected. DC subpopulation analyses revealed that elevation of respiratory DC was caused by an increase of respiratory monocytic DC and CD11b(hi) DC subsets. Lymphocyte subpopulation analyses indicated a marked elevation of respiratory natural killer cells and a significant reduction of B lymphocytes. Analysis of cytokine responses of respiratory leukocytes after stimulation with Klebsiella pneumonia indicated reduced IFN-γ and TNF-α expression and increased IL-10 and IL-12p70 production after 7 day low dose skin TLR7 triggering. Additionally, respiratory NK cytotoxic activity was increased after 7d skin TLR7 triggering. In contrast, lung histology and bronchoalveolar cell counts were not affected suggesting that skin TLR7 stimulation modulated respiratory leukocyte composition without inducing overt pulmonary inflammation. These data suggest the possibility to modulate respiratory leukocyte composition and respiratory cytokine responses against pathogens like Klebsiella pneumonia through skin administration of a clinically approved TLR7 ligand. Skin administration of synthetic TLR7 ligands may represent a novel, noninvasive means to modulate respiratory immunity.
    PLoS ONE 01/2012; 7(8):e43320. · 3.53 Impact Factor
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    ABSTRACT: Heparin-induced thrombocytopenia (HIT) is an adverse complication of heparin caused by HIT antibodies (abs) that recognise platelet factor 4-heparin (PF4/hep) complexes. Several laboratory tests are available for the confirmation and/or refutation of HIT. A reliable and rapid single-sample test is still pending. It was the objective of this study to evaluate a new lateral-flow immunoassay based on nanoparticle technology. A cohort of 452 surgical and medical patients suspected of having HIT was evaluated. All samples were tested in two IgG-specific ELISAs, in a particle gel immunoassay (PaGIA) and in a newly developed lateral-flow immunoassay (LFI-HIT) as well as in a functional test (HIPA). Clinical pre-test probability was determined using 4T's score. Platelet-activating antibodies were present in 34/452 patients, all of whom had intermediate to high clinical probability. PF4/hep abs were detected in 79, 87, 86, and 63 sera using the four different immunoassays. The negative predictive values (NPV) were 100% for both ELISA tests and LFI-HIT but only 99.2% for PaGIA. There were less false positives (n=29) in the LFI-HIT compared to any other test. Additionally, significantly less time was required to perform LFI-HIT than to perform the other immunoassays. In conclusion, a newly developed lateral-flow assay, LFI-HIT, was capable of identifying all HIT patients in a cohort in a short period of time. Beside an NPV of 100%, the rate of false-positive signals is significantly lower with LFI-HIT than with other immunoassay(s). These performance characteristics suggest a high potency in reducing the risk and costs in patients suspected of having HIT.
    Thrombosis and Haemostasis 12/2011; 106(6):1197-202. · 5.76 Impact Factor
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    ABSTRACT: Neonatal 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 (Sec(a)) residing on αIIbβ3. The location of Sec(a) on αIIbβ3 was confirmed by immunoprecipitation. Nucleotide sequence analysis of paternal β3 revealed a single nucleotide exchange (G(1818)T) in exon 11 of the β3 gene (ITGB3), changing Lys(580) (wild-type) to Asn(580) (Sec(a)). Two additional members of the family Sec were typed Sec(a) positive, but none of 300 blood donors. Chinese hamster ovary cells expressing Asn(580), but not Lys(580) αIIbβ3, bound anti-Sec(a), which was corroborated by immunoprecipitation. Adhesion of transfected cells onto immobilised fibrinogen showed reduced binding of the Asn(580) variant compared to wild-type αIIbβ3. Analysis of transfected cells with anti-LIBS and PAC-1 antibody showed reduced binding when compared to the wild-type. No such effects were observed with Sec(a) positive platelets, which, however, are heterozygous for the Lys(580)Asn mutation. In this study, we describe a NAIT case caused by maternal alloimmunisation against a new antigen on αIIbβ3. Analysis with mutant transfected cells showed that the Lys(580)Asn mutation responsible for the formation of the Sec(a) antigenic determinant affects αIIbβ3 receptor function.
    Thrombosis and Haemostasis 11/2011; 107(1):80-7. · 5.76 Impact Factor
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    ABSTRACT: Imidazoquinolone compounds, such as resiquimod are Toll-like receptor (TLR) 7/8 ligands representing novel immune response modifiers undergoing clinical testing. Resiquimod has been reported to modulate conventional human monocyte-derived DC (moDC) differentiation, but the role of TLR7 and TLR8 is unclear. We directly dissected the TLR7- and TLR8-dependency by employing selective TLR7 ligands and resiquimod-coculture experiments with inhibitory oligonucleotides (iODN) suppressing TLR7, TLR7+8 or TLR7+8+9. Selective TLR7 ligands did not affect conventional moDC differentiation as analyzed by CD14/CD1a expression. iODN experiments confirmed that resiquimod's effects during DC differentiation were antagonized only with TLR8 iODNs. Direct comparison of resiquimod DC with TLR7- and control-DC revealed significantly higher T-cell costimulatory molecule and MHC class II expression. Resiquimod DC promoted significantly stronger allogeneic T-cell proliferation and stronger naïve CD4(+) T-cell proliferation. These results indicate the relevance of TLR8 for human monocyte-derived DC differentiation and maturation and may be relevant for clinical trials employing resiquimod.
    Cellular Immunology 08/2011; 271(2):401-12. · 1.74 Impact Factor
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    ABSTRACT: Adipose tissue-derived mesenchymal stem cells (ASCs) are a promising stem cell source for cell transplantation. We demonstrate that undifferentiated ASCs display robust oscillations of intracellular calcium [Ca(2+) ](i) which may be associated with stem cell maintenance since oscillations were absent in endothelial cell differentiation medium supplemented with FGF-2. [Ca(2+) ](i) oscillations were dependent on extracellular Ca(2+) and Ca(2+) release from intracellular stores since they were abolished in Ca(2+) -free medium and in the presence of the store-depleting agent thapsigargin. They were inhibited by the phospholipase C antagonist U73,122, the inositol 1,4,5-trisphosphate (InsP(3) ) receptor antagonist 2-aminoethoxydiphenyl borate (2-APB) as well as by the gap-junction uncouplers 1-heptanol and carbenoxolone, indicating regulation by the InsP(3) pathway and dependence on gap-junctional coupling. Cells endogenously generated nitric oxide (NO), expressed NO synthase 1 (NOS 1) and connexin 43 (Cx 43). The nitric oxide NOS inhibitors NG-monomethyl-L-arginine (L-NMMA), N(G)-nitro-L-arginine methyl ester (L-NAME), 2-ethyl-2-thiopseudourea, and diphenylene iodonium as well as si-RNA-mediated down-regulation of NOS 1 synchronized [Ca(2+) ](i) oscillations between individual cells, whereas the NO-donors S-nitroso-N-acetylpenicillamine (SNAP) and sodium nitroprusside (SNP) as well as the soluble guanylate cyclase inhibitor 1H-[1,2,4]oxadiazolo-[4,3-a]quinoxalin-1-one (ODQ) were without effects. The synchronization of [Ca(2+) ](i) oscillations was due to an improvement of intracellular coupling since fluorescence recovery after photobleaching (FRAP) revealed increased reflow of fluorescent calcein into the bleached area in the presence of the NOS inhibitors DPI and L-NAME. In summary our data demonstrate that intracellular NO levels regulate synchronization of [Ca(2+) ](i) oscillations in undifferentiated ASCs by controlling gap-junctional coupling.
    Journal of Cellular Physiology 06/2011; 226(6):1642-50. · 4.22 Impact Factor

Publication Stats

2k Citations
511.09 Total Impact Points

Institutions

  • 1998–2014
    • Justus-Liebig-Universität Gießen
      • • Department of Internal Medicine
      • • Department of Anaesthesiology and Intensive Care Medicine
      • • Institut für Medizinische Psychologie
      Gieben, Hesse, Germany
  • 2013
    • University of Greifswald
      • Institute of Immunology and Transfusion Medicine
      Greifswald, Mecklenburg-Vorpommern, Germany
    • Philipps University of Marburg
      Marburg, Hesse, Germany
    • National Institutes of Health
      Maryland, United States
  • 2012
    • University of Rostock
      • Transfusionsmedizin
      Rostock, Mecklenburg-Vorpommern, Germany
  • 2008–2012
    • Universitätsklinikum Gießen und Marburg
      Marburg, Hesse, Germany
  • 1991–2008
    • Universität zu Lübeck
      • • Institut für Transfusionsmedizin
      • • Department of Internal Medicine I
      Lübeck Hansestadt, Schleswig-Holstein, Germany
  • 1999–2004
    • Ludwig-Maximilians-University of Munich
      München, Bavaria, Germany
  • 1997
    • Humboldt State University
      Arcata, California, United States
    • Humboldt-Universität zu Berlin
      Berlín, Berlin, Germany
  • 1993
    • Institute for Transfusion Medicine
      Pittsburgh, Pennsylvania, United States