Anti-FcγRIIB (CD32) Antibodies Differentially Modulate Murine FVIII-Specific Recall Response in vitro.

Fc gamma receptors (FcγRs) for IgG regulate adaptive immune responses by modulating activating and inhibitory signalling pathways within immune cells. Data from a haemophilia A mouse model demonstrate that genetic deletion or blockade of the inhibitory FcγR (CD32) suppresses the formation of antibody-secreting cells (ASCs) in vitro. Mechanisms preventing the FVIII-specific recall response, however, remain unclear. Here, the potential role of CD32 inhibition was studied by differentially modulating receptor activity with selected anti-CD32 monoclonal antibodies (mAbs). Splenocytes from immunized FVIII-/- mice were restimulated with FVIII in the absence or presence of different anti-CD32 mAbs over 6 days. At day 6, cytokine release was quantified from cell culture supernatant and the formation of FVIII-specific ASCs assessed. Binding of FVIII-containing immune complexes (F8-ICs) to bone marrow-derived dendritic cells (BMdDCs) was also investigated. The antagonistic CD32 mAb AT128 suppressed the formation of FVIII-specific ASCs and reduced secretion of IFN-γ and IL-10. In contrast, the agonistic mAbs AT130-2 and AT130-5, and their F(ab')2 fragments, allowed the formation of FVIII-specific ASCs, even though the full IgG of AT130-2 reduced binding of F8-ICs to CD32. Data suggest that an inhibitory signal is transmitted when F8-ICs bind to CD32 and that this signal is required during memory B cell (MBC) activation to support formation of FVIII-specific ASCs. If the inhibitory signal is lacking due to CD32 deletion or blockade with antagonistic anti-CD32 mAbs, FVIII-specific T cell stimulation and ASC formation are suppressed, whereas agonistic stimulation of CD32 restores T cell stimulation and ASC formation.

Co-morbidities and bleeding in elderly patients with haemophilia-A survey of the German, Austrian and Swiss Society of Thrombosis and Haemostasis Research (GTH).

BACKGROUND: Nowadays patients with haemophilia survive longer due to improvements in haemophilia care. It has been hypothesized that the bleeding type and frequency may vary with age and are influenced by co-morbidities and co-medication in elderly patients. OBJECTIVES: To investigate a large group of patients older than 60 years of age with haemophilia concerning haemophilia treatment, bleeding pattern changes, co-morbidities, co-medication, bleeding sites and patient mortality. METHODS: A retrospective multi-centre data collection study was initiated on behalf of the German, Austrian and Swiss Society of Thrombosis and Haemostasis Research (GTH). Parameters of interest were investigated over the 5 years prior to study entry. RESULTS: A total of 185 haemophilia patients (mean age, 69.0±7.0 years, 29% with severe haemophilia) were included in the study. Regular prophylaxis was performed in 30% of the patients with severe haemophilia. In total, the annual bleeding rate was 2.49 and in patients with severe haemophilia 5.61, mostly caused by joint bleeds. Hypertension was the most common co-morbidity, but it occurred significantly less frequently than in an age-matched general population older than 70 years; 12% of the patients suffered from ischaemic heart disease, and 13% of the patients received anticoagulant or antiplatelet therapy. Within the observation period, 17% of the patients with severe haemophilia developed a higher frequency of bleeding symptoms, which was significantly associated with the use of antiplatelet or anticoagulant drugs. CONCLUSIONS: The most common co-morbidity of the patient population was hypertension, a considerable part had ischemic heart disease and antiplatelet or anticoagulant drugs.

Pharmacokinetics of a novel extended half-life glycoPEGylated factor IX, nonacog beta pegol (N9-GP) in previously treated patients with haemophilia B: results from two phase 3 clinical trials.

INTRODUCTION: Nonacog beta pegol (N9-GP) is a glycoPEGylated recombinant factor IX (FIX) with an extended half-life developed for routine prophylaxis and the prevention and treatment of bleeding episodes in patients with haemophilia B. AIM: The aim of this study was to evaluate the pharmacokinetics (PK) of N9-GP. METHODS: Data from 41 previously treated haemophilia B patients, enrolled globally (16 adolescents/adults and 25 children; FIX activity ≤0.02 IU mL-1 ) with no history of FIX inhibitors, were included. N9-GP was administered once-weekly as 10 IU kg-1 or 40 IU kg-1 in adolescents/adults and 40 IU kg-1 in children. Blood was sampled up to 168 h (1 week) post dose. Standard PK was estimated on the basis of plasma FIX activity vs. time (PK profiles) using non-compartmental methods. Furthermore, a population PK analysis and FIX activity predictions were performed. RESULTS: Incremental recoveries were 0.02 (IU mL-1 )/(IU kg-1 ) in both adolescents/adults and children. The extended half-life resulted in mean trough levels of 0.27 IU mL-1 for adolescents/adults and 0.17 IU mL-1 for children at steady-state after weekly dosing at 40 IU kg-1 . The population PK analysis confirmed a mono-exponential decay in FIX activity and allowed for predictions of FIX activity for adolescents/adults above 0.15 IU mL-1 at all times and 6.4 days week-1 in children. CONCLUSION: N9-GP has the potential to shift previously treated haemophilia B patients from a severe/moderate disease state into a mild- or non-haemophilic range for most of the dosing interval, which is expected to reduce the number of bleeding episodes.

PK-guided personalized prophylaxis with Nuwiq® (human-cl rhFVIII) in adults with severe haemophilia A.

INTRODUCTION: Nuwiq® (human-cl rhFVIII) is a 4th generation recombinant human FVIII, without chemical modification or protein fusion, produced in a human cell-line. AIMS/METHODS: This study (NuPreviq) was a prospective, open-label, multicentre, phase IIIb study of the efficacy and safety of personalized prophylaxis with Nuwiq® in 66 previously treated adults with severe haemophilia A. NuPreviq had three phases: (i) a 72-h pharmacokinetic (PK) phase; (ii) a 1-3 month standard prophylaxis phase; and (iii) a 6-month personalized prophylaxis phase. The personalized prophylaxis regimen was based on individual PK modelling for each patient according to whether their PK profile most closely fitted a two- or one-compartment model (NuPreviq approach). In cases of uncertainty, a noncompartment model was applied. RESULTS: The median dosing interval during personalized prophylaxis was 3.5 days, with 57% of patients on ≤2 weekly dosing. Mean annualized bleeding rates during personalized prophylaxis were 1.45 (median [interquartile range, IQR]: 0 [0, 1.9]) for all bleeds, 0.79 (median [IQR]: 0 [0, 0]) for spontaneous bleeds, and 0.91 (median [IQR]: 0 [0, 0]) for joint bleeds. During personalized prophylaxis, 83.1% of patients were spontaneous bleed-free. Compared with standard prophylaxis, median weekly prophylaxis dose was reduced by 7.2% from 100.0 to 92.8 IU kg-1 during the last 2 months of personalized prophylaxis. There were no FVIII inhibitors or treatment-related serious or severe adverse events. CONCLUSION: PK-guided personalized prophylaxis with Nuwiq® provided bleeding protection and enabled the dosing interval to be extended to twice weekly or less in many patients and an overall dose reduction.

Prophylaxis vs. on-demand treatment with Nuwiq(®) (Human-cl rhFVIII) in adults with severe haemophilia A.

INTRODUCTION: Haemophilia A is treated with FVIII, either prophylactically or on demand. Prophylaxis is the gold standard in children and evidence is accumulating in adults. AIMS/METHODS: The aim of this analysis was to compare prophylaxis vs. on-demand treatment with Nuwiq(®) (Human-cl rhFVIII), a new-generation rFVIII expressed in a human cell line, in previously treated patients (PTPs) with severe haemophilia A. Data were analysed from two similarly designed, multinational, prospective, open-label studies with similar inclusion and exclusion criteria and comparable patient demographics. Human-cl rhFVIII was administered either prophylactically in a study of 32 adults or on-demand in a study of 22 patients (20 adults and two adolescents). RESULTS: Patients treated prophylactically experienced 36 bleeds compared with 997 bleeds in patients treated on-demand (mean observation periods: 180 and 335 days respectively). Based on a negative binomial regression model, annualized bleeding rate (ABR) during prophylaxis was 2.30 (95% CI: 1.54, 3.44) compared with 57.74 (95% CI: 43.36, 76.91) during on-demand treatment, which equates to a 96% lower ABR during prophylaxis. 'Excellent' or 'good' efficacy in the treatment of bleeds was achieved with Human-cl rhFVIII in 100% of 28 evaluated bleeds during the prophylaxis study and 94.5% of 985 evaluated bleeds during the on-demand study. No inhibitors, treatment-related serious adverse events or severe adverse events were recorded during prophylaxis or or-demand treatment. CONCLUSIONS: Prophylaxis with Human-cl rhFVIII reduces recurrent bleeding in adult PTPs with severe haemophilia A and adds further supportive evidence for the benefits of prophylaxis in adults.

siRNA mediated knockdown of tissue factor expression in pigs for xenotransplantation.

Acute vascular rejection (AVR), in particular microvascular thrombosis, is an important barrier to successful pig-to-primate xenotransplantation. Here, we report the generation of pigs with decreased tissue factor (TF) levels induced by small interfering (si)RNA-mediated gene silencing. Porcine fibroblasts were transfected with TF-targeting small hairpin (sh)RNA and used for somatic cell nuclear transfer. Offspring were analyzed for siRNA, TF mRNA and TF protein level. Functionality of TF downregulation was investigated by a whole blood clotting test and a flow chamber assay. TF siRNA was expressed in all twelve liveborn piglets. TF mRNA expression was reduced by 94.1 ± 4.7% in TF knockdown (TFkd) fibroblasts compared to wild-type (WT). TF protein expression in PAEC stimulated with 50 ng/mL TNF-α was significantly lower in TFkd pigs (mean fluorescence intensity TFkd: 7136 ± 136 vs. WT: 13 038 ± 1672). TF downregulation significantly increased clotting time (TFkd: 73.3 ± 8.8 min, WT: 45.8 ± 7.7 min, p < 0.0001) and significantly decreased thrombus formation compared to WT (mean thrombus coverage per viewing field in %; WT: 23.5 ± 13.0, TFkd: 2.6 ± 3.7, p < 0.0001). Our data show that a functional knockdown of TF is compatible with normal development and survival of pigs. TF knockdown could be a valuable component in the generation of multi-transgenic pigs for xenotransplantation.

Spotlight on the human factor: building a foundation for the future of haemophilia A management: report from a symposium on human recombinant FVIII at the World Federation of Hemophilia World Congress, Melbourne, Australia on 12 May 2014.

Inhibitor development is the most serious and challenging complication in the treatment of severe haemophilia A. Up to 38% of such patients develop inhibitors with current recombinant factor VIII (rFVIII) products produced in hamster cell lines. Human-cl rhFVIII is a new generation fully sulfated B-domain-deleted FVIII coagulant glycoprotein, which is generated from a human cell line. Thus, there are no non-human epitopes which would be potentially immunogenic. This molecule has significantly higher VWF-binding affinity compared with existing full-length rFVIII produced in hamster cell lines. The development aim of Human-cl rhFVIII is to address the challenges of FVIII inhibitors and frequent infusions during prophylaxis. Human-cl rhFVIII's mean half-life is very comparable to some of the newer products which involve modification of the FVIII molecule to extend the circulating half-life. There are promising data concerning the use of a personalized prophylaxis regimen with Human-cl rhFVIII. Preliminary data indicate a median dosing interval of 3.5 days with 66.7% of the patients on a twice per week or fewer infusions schedule combined with a low bleeding rate and no increased FVIII consumption when compared to standard prophylaxis. No product-specific laboratory assay is required to monitor the coagulation activity for Human-cl rhFVIII. The results of registration clinical trials with Human-cl rhFVIII as well as the ongoing studies in previously untreated patients (NuProtect) and personalized prophylaxis study in previously treated patients (NuPreviq), will be discussed. The manufacturer has received marketing authorization for Human-cl rhFVIII in Europe and Canada under the name Nuwiq(®) and plans to launch it in the USA and globally in 2015.

A comprehensive analysis of the cellular and EBV-specific microRNAome in primary CNS PTLD identifies different patterns among EBV-associated tumors.

Primary central nervous system (pCNS) posttransplant lymphoproliferative disorder (PTLD) is a complication of solid organ transplantation characterized by poor outcome. In contrast to systemic PTLD, Epstein-Barr virus (EBV)-association of pCNS PTLD is almost universal, yet viral and cellular data are limited. To identify differences in the pattern of EBV-association of pCNS and systemic PTLD, we analyzed the expression of latent and lytic EBV transcripts and the viral and cellular microRNAome in nine pCNS (eight EBV-associated) and in 16 systemic PTLD samples (eight EBV-associated). Notably although 15/16 EBV-associated samples exhibited a viral type III latency pattern, lytic transcripts were also strongly expressed. Members of the ebv-miR-BHRF1 and ebv-miR-BART clusters were expressed in virtually all EBV-associated PTLD samples. There were 28 cellular microRNAs differentially expressed between systemic and pCNS PTLD. pCNS PTLD expressed lower hsa-miR-199a-5p/3p and hsa-miR-143/145 (implicated in nuclear factor kappa beta and c-myc signaling) as compared to systemic PTLD. Unsupervised nonhierarchical clustering of the viral and cellular microRNAome distinguished non-EBV-associated from EBV-associated samples and identified a separate group of EBV-associated pCNS PTLD that displayed reduced levels of B cell lymphoma associated oncomiRs such as hsa-miR-155, -21, -221 and the hsa-miR-17-92 cluster. EBV has a major impact on viral and cellular microRNA expression in EBV-associated pCNS PTLD.

Pharmacokinetics, phenotype and product choice in haemophilia B: how to strike a balance?

At the 7th Annual Congress of the European Association for Haemophilia and Allied Disorders (EAHAD) held in Brussels, Belgium, in February 2014, Pfizer sponsored a satellite symposium entitled: "Pharmacokinetics, phenotype and product choice in haemophilia B: How to strike a balance?" Co-chaired by Cedric Hermans (Cliniques Universitaires Saint Luc, Brussels, Belgium) and Mike Laffan (Imperial College, London, UK), the symposium provided an opportunity to debate whether pharmacokinetic (PK) parameters are good surrogates for clinical efficacy for haemophilia B in clinical practice, consider the perceptions and evidence of disease severity, and examine how these considerations can inform approaches to balancing the potential risks and benefits of the currently available treatment options for haemophilia B. PK parameters are routinely measured in clinical practice and are a requirement of regulatory bodies to demonstrate the clinical efficacy of products; however, the relationship between measured PK parameters and clinical efficacy is yet to be determined, an issue that was debated by Gerry Dolan (University Hospital, Queen's Medical Centre, Nottingham, UK) and Erik Berntorp (Lund University, Malmö Centre for Thrombosis and Haemostasis, Malmö, Sweden). Elena Santagostino (Universita degli Studi di Milano, Milano, Italy) reviewed how differing perceptions on the severity of haemophilia B compared with haemophilia A may have an impact on clinical decision-making. Finally, Andreas Tiede (Hannover Medical School, Hannover, Germany), examined the considerations for balancing the potential risks and benefits of the currently available treatment options for haemophilia B. Although the pathophysiology of haemophilia B has been widely studied and is largely understood, continued investigation and discussion around the optimal management course and appropriate therapeutic choice is warranted.

The first recombinant FVIII produced in human cells--an update on its clinical development programme.

The development of inhibitors and the need for frequent venous access for FVIII injection are major challenges in current haemophilia treatment. Presently available recombinant FVIII (rFVIII) products produced in hamster cell lines are associated with inhibitor formation in up to 32% of previously untreated patients. The new human cell line-derived recombinant human FVIII (Human-cl rhFVIII) protein is the first native, unmodified truly human rFVIII product produced in a human cell line without additive animal proteins. The aim of using a human cell line for the production of rFVIII is the avoidance of non-human epitopes on rFVIII, thereby potentially reducing the rate of inhibitor development, avoiding allergic reactions and allowing personalized prophylaxis with the chance of fewer infusions. Studies to date show that prophylaxis with Human-cl rhFVIII prevents 96% of bleeding events in adults with severe haemophilia A when compared to on-demand treatment. Available pharmacokinetic data with a mean half-life of 17.1 h allow personalized prophylaxis with the chance of fewer infusions. Studies in previously treated children and adults indicate that Human-cl rhFVIII is efficacious and safe in the prevention and treatment of bleeding episodes and that none of the treated patients developed inhibitors or allergic reactions thus far.

Increased amounts of von Willebrand factor are bound to microparticles after infusion of desmopressin.

Effects of desmopressin (DDAVP) in platelet disorders and primary haemostasis cannot be attributed solely to the increase in FVIII/VWF (von Willebrand factor), as VWF/FVIII concentrates have no effect in these circumstances. Microparticles (MP) can support haemostasis by expression of phospholipids, tissue factor and VWF on their surface. We hypothesized that significant amounts of VWF are bound to MP after DDAVP administration and that consequently depletion of MP should influence VWF:Ag and VWF:RCo plasma levels. Platelet-poor plasma was either obtained well from healthy controls or before and after DDAVP administration from patients with von Willebrand's disease (type 1 or possible type 1) or patients with other bleeding disorders as controls. Concentrations of MP and VWF parameters were determined before and after MP depletion by different methods (magnetic bead selection, plasma microfiltration, ultracentrifugation). Platelet MP and VWF-bearing MP were significantly increased after DDAVP. MP depletion by magnetic bead selection led to a significant reduction in VWF:Ag (-18.0%) and VWF:RCo (-27.7%) plasma levels without changes in VWF multimer composition. As results were similar for DDAVP control subjects, the amount of VWF bound to circulating microparticles was significantly higher after DDAVP administration compared with healthy controls (reduction -11.7%). DDAVP leads to a release of microparticles and increases the amount of VWF bound to microparticles which might explain the clinical efficacy of DDAVP in platelet disorders.

Results from a large multinational clinical trial (guardian™1) using prophylactic treatment with turoctocog alfa in adolescent and adult patients with severe haemophilia A: safety and efficacy.

Recombinant factor VIII (rFVIII) products provide a safe and efficacious replacement therapy for prophylaxis and treatment of bleeding episodes in patients with severe haemophilia A. This multinational, open-label, non-controlled trial investigated the safety and efficacy of turoctocog alfa, a new rFVIII product. The primary objective was to evaluate safety. A total of 150 patients (24 adolescents and 126 adults) with severe haemophilia A (FVIII activity ≤ 1%), with at least 150 exposure days (EDs) to any FVIII product and no history of inhibitors were enrolled, and 146 patients (97%) completed the trial. All patients received prophylaxis with turoctocog alfa for approximately 6 months and had a mean of 85 EDs during the trial. None of the patients developed FVIII inhibitors, there were no indications of early FVIII inhibitor development and no safety concerns were identified. A total of 225 adverse events were reported in 100 (67%) patients, with the most common being events associated with dosing procedures, headaches, and nasopharyngitis. A total of 499 bleeding episodes were reported during the trial, the majority (89%) were controlled with 1-2 infusions of turoctocog alfa. Based on patient reports, the success rate (defined as 'excellent' or 'good' haemostatic response) for treatment of bleeding episodes was 81%. The overall median annualized bleeding rate was 3.7 (interquartile range: 8.7) bleeds/patient/year. In conclusion, turoctocog alfa provides a new, safe and effective alternative for prophylaxis and treatment of bleeding episodes in patients with haemophilia A.

Effects of platelet concentrate storage time reduction in patients after blood stem cell transplantation.

OBJECTIVE: To evaluate the clinical effect of platelet concentrate (PC) transfusions after PC storage time reduction to 4 days. PATIENTS AND METHODS: This was a single-centre cohort study comparing two 3-month periods of time, before and after the reduction of PC storage time from 5 to 4 days. Seventy-seven consecutive patients with PC transfusions were enrolled after blood stem cell transplantation. Corrected platelet count increment (CCI) on the morning after transfusion, time to next platelet transfusion, need for red blood cell (RBC) transfusion and clinical bleeding symptoms were compared. RESULTS: Platelet concentrate storage time was reduced between period 1 (storage for up to 5 days, median storage time 78 h, range 11-136 h) and period 2 (storage for up to 4 days, median storage time 53 h, range 11-112 h). Patients were comparable for age, weight, body surface area, underlying disorder, type of transplantation and transfused platelet dose. The CCI increased from a median of 4 (range 0-20) to 8 (0-68) × 10(9) /l per 10(11) platelets/m(2) (P < 0·0001). Time to next PC transfusion increased from 1·1 to 2·0 days (P < 0·0001). Any bleeding symptom was noted in 20 of 36 patients (56%) vs. 9/41 patients (22%, P < 0·01). Nose bleeds, haematuria and bleeding at more than one site were significantly reduced. Frequency of RBC transfusion within 5 days after PC transfusion was reduced from 74 to 58% (P < 0·0001). CONCLUSION: Platelet concentrate storage time shortening was associated with highly significant CCI increase, reduced RC needs and lower patient numbers with bleeding events.

On-demand treatment of bleeds in haemophilia patients with inhibitors: strategies for securing and maintaining predictable efficacy with recombinant activated factor VII.

On-demand therapy with recombinant activated factor VII (rFVIIa) can provide effective haemostasis for spontaneous bleeds in haemophilia patients with inhibitors. However, treatment approaches vary amongst physicians, positively or negatively affecting outcomes. A panel of physicians proposed recommendations for securing and maintaining predictable efficacy with rFVIIa, comparing these with 'real-life' patient management, using a questionnaire circulated to other expert physicians from haemophilia care centres in Europe and the United States. For rFVIIa treatment of spontaneous bleeds in inhibitor patients, early intervention with the highest appropriate dose is recommended. Home-based therapy can facilitate early intervention. If additional rFVIIa therapy is required after the initial dose, rFVIIa 90 µg kg(-1) may be administered at 2-3 h intervals. Treatment should be tailored to bleed site/severity, recognizing the advantages of appropriate adjunct therapy. Questionnaire results suggested that many respondents adopted strategies in line with the recommendations. Most (36/46) recommended initial therapy within 1 h of bleed onset. rFVIIa 270 µg kg(-1) was the most frequently prescribed/recommended initial dose for paediatric (aged ≤ 15 years; 22/44 respondents) and adult (aged > 15 years; 23/44 respondents) patients. However, there may be opportunity for improved bleed management on occasion, with regard, for instance, to dosing and dose interval. To secure and maintain predictable efficacy with rFVIIa, judicious dose selection and treatment timing are important, together with adjunct therapy where necessary. As inhibitor patients present with different bleeding scenarios, a tailored treatment approach should be adopted.

Bioequivalence between two serum-free recombinant factor VIII preparations (N8 and ADVATE®)--an open-label, sequential dosing pharmacokinetic study in patients with severe haemophilia A.

Recombinant coagulation factor VIII (rFVIII) concentrates provide a safe and efficacious replacement therapy for treatment and prevention of bleeding in patients with severe haemophilia A. The aim of this study was to compare the pharmacokinetic (PK) and safety profiles of two serum-free rFVIII products: N8, a new rFVIII manufactured by Novo Nordisk and Advate(®), a marketed product. Patients with severe haemophilia A with >150 exposure days to FVIII, without current or past inhibitors, were enrolled in an open-label, first human dose (FHD), multicentre trial. Twenty-three patients first received a single dose of 50 IU kg(-1) body weight Advate(®) followed by 50 IU kg(-1) body weight N8 at the next visit. A 4-day washout period was required prior to each dosing. Blood samples for PK and safety analyses were drawn prior to dosing and at intervals up until 48 h postdosing. The PK parameters were based on FVIII clotting activity (FVIII:C) measurements. Occurrence of adverse events was closely monitored. The mean profiles of FVIII:C and all primary and secondary parameters for Advate(®) and N8 were comparable. The 90% CI for the treatment ratio (Advate(®)/N8) for all primary endpoints (incremental recovery, t(1/2), AUC and Cl), and the secondary endpoints (AUC(last) and C(max)) were within the bioequivalence interval of 0.8-1.25. There were no safety concerns in the study and no reports of inhibitor formation in the 72-h period following exposure to a single N8 dose. In conclusion, N8 is bioequivalent to Advate(®). Furthermore, N8 is well tolerated in the FHD trial.

Treatment of lupus-prone NZB/NZW F1 mice with recombinant soluble Fc gamma receptor II (CD32).

OBJECTIVES: Systemic lupus erythematosus (SLE) is a classical autoimmune disorder characterised by the production of IgG autoantibodies against double-stranded DNA (dsDNA). Activation of Fc gamma R-bearing effector cells by immune complexes (ICs) is a key event in SLE pathogenesis as lupus-prone NZB/NZW F(1) hybrids lacking activating Fc gamma receptors (Fc gamma R) are protected against inflammatory kidney damage despite glomerular deposition of ICs. Moreover, soluble Fc gamma Rs inhibit IC-caused Arthus reaction in vivo. Therefore, recombinant human soluble Fc gamma RII (CD32) was evaluated as a novel therapeutic strategy in lupus-like disease in NZB/NZW F(1) hybrids. METHODS: Binding of husCD32 to murine IgG was studied in vitro by binding to IgG-coated erythrocytes and inhibition of phagocytosis of IgG-opsonised murine erythrocytes. In order to examine therapeutic impact of husCD32 in vivo, female NZB/NZW F(1) mice were treated either from week 16 to 20 ("prophylactic", 150 microg/week husCD32) or continuously from week 24 ("therapeutic"; 100 microg/week husCD32) by subcutaneous injections. Controls received buffered saline. RESULTS: In vitro investigations of husCD32 revealed binding to murine erythrocytes coated with murine IgG. Moreover, husCD32 substantially diminished phagocytosis of murine IgG-opsonised murine red blood cells by peritoneal macrophages indicating disruption of IgG-Fc gamma R interaction. There was a therapeutic efficacy of husCD32 to attenuate lupus pathology indicated by significantly delayed onset of proteinuria and weight loss, reduced histopathological findings, delayed development of anaemia and improved survival by prophylactic application. Therapeutic treatment did not reverse nephritis but significantly prolonged survival despite apparent kidney damage. B cell count, concentration of IgG anti-dsDNA autoantibodies and deposition of glomerular ICs was not significantly affected by the application of husCD32. CONCLUSIONS: The results demonstrate binding properties of husCD32 to ICs in vitro and as a proof-of-principle therapeutic efficacy in inhibiting chronic murine lupus pathology in vivo.

CD8alpha+beta(low) effector T cells in systemic lupus erythematosus.

Systemic lupus erythematosus (SLE) is a complex autoimmune disorder characterized by the loss of self-tolerance to nuclear antigens. Aberrant T-cell function plays a central role in lupus pathogenesis. We and others previously demonstrated that peripheral TCRalphabeta+CD3+ T cells express CD8beta either at a high (CD8beta(high)) or low density (CD8beta(low)), thereby defining two functionally distinct subsets. CD8beta(low) T cells express predominantly CD8alphaalpha and less CD8alphabeta as a coreceptor, display a differentiated phenotype and exert effector function. CD8beta(high) T cells appear to be the precursors expressing predominantly the heterodimeric efficient CD8alphabeta coreceptor, exhibiting a naïve phenotype and high proliferative capacity. In the present study, the distribution and functional properties of CD8beta(high) and CD8beta(low) T cells of SLE patients were compared (n = 20) with those of healthy subjects (n = 16). It was found that expansion of CD8beta(low) T-cell subset correlated with disease activity indicating chronic antigenic stimulation leading to a major lack of naïve CD8beta(high) precursor T cells in SLE. Functional characteristics of CD8beta(low) T cells including production of cytokines and cytotoxic granules were not significantly different between patients with SLE and healthy individuals. We speculate that unbalanced CD8beta(high)/CD8beta(low) T-cell relation reflects a skewed homeostasis within the CD8+ T-cell compartment towards fully differentiated effector T cells possibly due to persistent antigen stimulation in SLE.

Thrombelastographic monitoring of recombinant factor VIIa in acquired haemophilia.

Monitoring of the global haemostatic capacity is desired to optimize the treatment with bypassing agents in inhibitor patients. Thrombelastographic methods have been used in ex vivo studies and were suggested useful to evaluate the individual response to bypassing agents. This study aimed at assessing changes in thrombelastographic profiles and their association to clinical outcome in patients treated with recombinant factor VIIa (rFVIIa). Ten patients with acquired haemophilia were treated with rFVIIa for acute bleeding. Thrombelastography was performed after activation with a small amount of tissue factor in samples obtained before and after in vivo administration of rFVIIa. In patients studied before and after a first dose, correction of the thrombelastographic profile was observed but did not predict cessation of bleeding. During steady-state dosing, the median Alpha angle tended to be higher in patients with a good clinical treatment response as compared with patients with a partial or poor response. Similar trends were observed for clotting time and clot formation time. A good clinical treatment response was more frequent in patients with a fully corrected trough-level thrombelastographic profile as compared with patients with an abnormal profile. However, a poor treatment response was observed also in a surgical patient with a normal thrombelastographic profile during steady-state dosing. In conclusion, thrombelastographic monitoring was sensitive to haemostatic changes in response to treatment with rFVIIa. In the limited number of patients studied here, a better clotting profile during steady-state dosing was associated with a better clinical treatment response.

Inhibitor-Immunology-Study. Different HLA-types seem to be involved in the inhibitor development in haemophilia A.

UNLABELLED: The development of inhibitors is one of the most important complications of replacement therapy in haemophilia, affecting mortality and morbidity. Inhibitor development is based on complex immunological factors. Cytokines and their receptors, T-cell receptors, and the Major Histocompatibility Complex may play important roles in the development of inhibitors. Earlier studies showed non significant associations between HLA class and inhibitor development. Later studies found an increased risk of inhibitor development if there was a combination between certain factor VIII mutations and HLA antigens. We performed HLA typing in 50 patients with haemophilia A in an effort to find associations with inhibitor development. RESULTS: 25 patients had developed an inhibitor (11 low titre, 14 high titre), and 25 never had. In logistic regression analysis, HLA-A 34, DRB1 0405, DRB1 1301 seemed to be involved in inhibitor development and HLA-A 30, B 13, B15, B 57, Cw 12, DQB1 0303, DPB1 0201 protection against inhibitor development. In our patients, the HLA-associations with inhibitor development were different from those in previous publications.