Treatment of Alzheimer disease using combination therapy with plasma exchange and haemapheresis with albumin and intravenous immunoglobulin: Rationale and treatment approach of the AMBAR (Alzheimer Management By Albumin Replacement) study. / Tratamiento de la enfermedad de Alzheimer mediante terapia combinada de aféresis terapéutica y hemoféresis con albúmina e inmunoglobulina intravenosa: fundamentos y aproximación terapéutica al estudio AMBAR (Alzheimer Management By Albumin Replacement).

INTRODUCTION: There is a growing interest in new therapeutic strategies for the treatment of Alzheimer disease (AD) which focus on reducing the beta-amyloid peptide (Aß) burden in the brain by sequestering plasma Aß, a large proportion of which is bound to albumin and other proteins. This review discusses the concepts of interaction between Aß and albumin that have given rise to AMBAR (Alzheimer's Disease Management by Albumin Replacement) project, a new multicentre, randomised, controlled clinical trial for the treatment of AD. DEVELOPMENT: Results from preliminary research suggest that Albutein(®) (therapeutic albumin, Grifols) contains no quantifiable levels of Aß. Studies also show that Albutein(®) has Aß binding capacity. On the other hand, AD entails a high level of nitro-oxidative stress associated with fibrillar aggregates of Aß that can induce albumin modification, thus affecting its biological functions. Results from the phase ii study confirm that using therapeutic apheresis to replace endogenous albumin with Albutein(®) 5% is feasible and safe in patients with AD. This process resulted in mobilisation of Aß and cognitive improvement in treated patients. The AMBAR study will test combination therapy with therapeutic apheresis and haemopheresis with the possible leverage effect of Albutein(®) with intravenous immunoglobulin replacement (Flebogamma(®) DIF). Cognitive, functional, and behavioural changes in patients with mild to moderate AD will be assessed. CONCLUSIONS: the AMBAR study represents a new therapeutic perspective for AD.

Native plasma-derived FVIII/VWF complex has lower sensitivity to FVIII inhibitors than the combination of isolated FVIII and VWF proteins. Impact on Bethesda assay titration of FVIII inhibitors.

Sensitivity to FVIII inhibitors of the native plasma-derived (pd) FVIII/VWF complex vs. the complexes formed after exogenous FVIII infusion in the haemophilic patient has not been thoroughly studied. The role of VWF in the interaction of FVIII with inhibitors was studied in vitro using different combinations of VWF and FVIII concentrates. Normal plasma, pdFVIII/VWF and isolated FVIII (recombinant FVIII, B-domain deleted and pdFVIII) were used. Titre (BU) was kinetically determined (up to 2 h) in serial dilutions of inhibitor IgG (purified from a pool of plasmas with inhibitors) mixed with VWF and then incubated with the different FVIII. Inhibitor was also added to previously mixed VWF+FVIII. Residual FVIII:C was determined. TGA assays were performed with FVIII-deficient plasma spiked with the FVIII-VWF mixtures with/without an ESH-8 antibody. Inhibitor titres for plasma and pdFVIII/VWF were comparable at all time points. Titres for all concentrates of isolated FVIII were significantly higher than those for plasma or pdFVIII/VWF (1.4-1.9 fold) even after preincubation with VWF. At t = 0 h, titres for plasma or pdFVIII/VWF were unquantifiable, but were detectable for isolated FVIII (0.6-1.6 BU). In contrast to pdFVIII/VWF, the decrease in thrombin generation parameters by isolated FVIII in the presence of ESH-8 was significant (P < 0.01) even when previously combined with VWF. In conclusion, VWF protection against FVIII inhibitor activity might be higher with native pdFVIII/VWF complex than with the corresponding compound formed from the isolated proteins. Bethesda assay titration using different FVIII concentrates would be advisable to guide the treatment of inhibitor patients.

Kinetics of the interaction between anti-FVIII antibodies and FVIII from therapeutic concentrates, with and without von Willebrand factor, assessed by surface plasmon resonance.

The presence of VWF in plasma-derived FVIII (pdFVIII/VWF) products has been pointed out as a key difference with recombinant FVIII (rFVIII) products with regard to immunogenicity. A Surface Plasmon Resonance (SPR) study was designed to characterize in detail the interaction between anti-FVIII (IgGs) from a severe haemophilia A patient, and FVIII from concentrates of different sources. Full-length rFVIII (preincubated or not with purified VWF), B domain-deleted (BDD)-rFVIII and pdFVIII/VWF were analysed. To ensure reproducible conditions for accurate determination of kinetic constants, a capture-based assay format was developed using protein G surfaces for specific and reversible coupling of endogenous anti-FVIII antibodies. Concentration ranges (nm) of FVIII products tested were 9-0.03 (rFVIII) and 6-0.024 (pdFVIII/VWF). The association with antibodies was monitored for 3-5 min, whereas dissociation of the complex was followed for 5-20-240 min. A strong interaction of rFVIII and BDD-rFVIII with patient's IgG was detected with the K (D) values in the low picomolar range (5.9 ± 3.0 and 12.7 ± 6.9 pm, respectively) and very slow dissociation rates, while pdFVIII/VWF showed only marginal binding signals. The VWF complexed rFVIII displayed reduced binding signals compared with uncomplexed rFVIII, but the K (D) was still in the picomolar range (4.1 ± 1.9 pm) indicating insufficient complex formation. rFVIII, alone or bound to exogenously added VWF, showed high affinity for anti-FVIII IgGs from a severe haemophilia A patient whereas pdFVIII/VWF did not. These results are in agreement with those studies that point towards rFVIII concentrates to be more immunogenic than pdFVIII concentrates.

Flebogamma 5% DIF development: rationale for a new option in intravenous immunoglobulin therapy.

Flebogamma 5% dual inactivation and filtration (DIF), a new 5% liquid intravenous immunoglobulin with a stability of 2 years when stored at temperatures between 2 and 30 degrees C, has been developed. This new product is the result of the accumulated experience provided by Flebogamma, with more than 30 million grams administered since 1992 in Europe and the United States, and the implementation of the latest technology to improve Flebogamma even more by increasing its viral safety margin further. In addition to the specific inactivation stage for Flebogamma 5% (pasteurization), the new process includes a solvent-detergent treatment and nanofiltration through a Planova filter down to 20 nm. The preparation presents a mean purity of 99.6 +/- 0.2% with a correct chromatographic profile. Percentage values of immunoglobulin (Ig)G subclasses are equivalent to the physiological values of normal serum. The content in IgA as well as other possible impurities is very low, and the product presents a mean result of 109 +/- 5% in the Fc fragment functionality assay, demonstrating the integrity of the IgG molecule. The functionality is also reflected in neutralization tests carried out against poliomyelitis, diphtheria, measles and vaccinia which, apart from the antibody titres determined by enzyme-linked immunosorbent assay, guarantees that antibodies are capable of reacting against these pathogens. Regarding safety, the combination of multiple methods with capacity to inactivate or remove biological agents which include chemical inactivation, heat inactivation, nanofiltration and precipitations, with very different mechanisms of action, provides Flebogamma 5% DIF very wide margins of safety regarding to potential pathogens.

Elimination capacity of a TSE-model agent in the manufacturing process of Alphanate/Fanhdi, a human factor VIII/VWF complex concentrate.

The variant Creutzfeldt-Jakob disease (vCJD) is a transmissible spongiform encephalopathy (TSE), mainly present in the UK and is associated with the ingestion of bovine products affected with bovine spongiform encephalopathy. Manufacturers of biological products must investigate the ability of their production processes to remove TSE agents. We studied the purification steps in the manufacturing process of two FVIII/VWF concentrates (Alphanate) and Fanhdi in their ability to eliminate an experimental TSE-model agent. Hamster scrapie strain 263K brain-derived materials were spiked into samples of the solutions taken before various stages during its production: 3.5% polyethylene glycol (PEG) precipitation, heparin affinity chromatography and saline precipitation/final filtrations. PEG precipitation and affinity chromatography were studied both as isolated and combined steps. TSE agent removal was determined using a laboratory scale model representative of the industrial manufacturing process. The prion protein (PrP(Sc)) was measured with Western blot and TSE infectivity was measured with bioassay. Western blot results were in agreement with those obtained by bioassay, showing a significant removal capacity in the production process: 3.21-3.43 log(10) for the PEG precipitation; about 3.45 log(10) for the affinity chromatography; and around 2.0 log(10) for the saline precipitation plus final filtrations. PEG precipitation and heparin affinity chromatography were demonstrated to be two complementary TSE-model agent removal mechanisms with total removal being the sum of the two. An overall reduction factor of around 8 log(10) can be deduced. The tests from the production process of FVIII/VWF complex concentrates have demonstrated their potential for eliminating TSE agents.

The importance of corticoids added to continued treatment with Factor VIII concentrates in the suppression of inhibitors in haemophilia A.

A protocol is presented to suppress inhibitors in haemophilia A using continued treatment with f. VIII (50 U/kg b.w./day) and fluprednisolone (0.5 mg/kg b.w., for 21 days) until reaching correct in vivo recovery after therapeutic administration. 5 high responder patients were treated whose inhibitors were detected at least 2 years before beginning the treatment. The inhibitors were eradicated in 4 patients using continued treatment for between 4 and 24 months. Patient 1 was treated exclusively with factor and the others also with corticoids when the level was 0 B.U. (or 20 B.U., patient 4). The patients began tri-weekly prophylactic treatment and rehabilitation exercises after recovery test normalization. After progressive reduction of the prophylactic treatment they started on demand treatment. After more than 5 months of this treatment no anamnestic response has been detected in any patient, in spite of several factor VIII administrations.

A standardized method for measuring anti-F VIII: C inhibitors in haemophilia A by coagulation inhibition in agarose gel.

Antibodies against factor-VIII coagulant activity can appear in haemophilic patients and, although infrequently, can affect individuals not suffering from Haemophilia A. The Oxford and Bethesda methods are presently the most commonly used techniques for measuring these antibodies. Both methods are time-consuming and not suitable for the screening of large risk groups. An appropriate method for screening these coagulation inhibitors is that described by P. Bird in 1975. It is based on inhibition of the coagulation produced when plasma samples containing inhibitors diffuse in agarose gels mixed with normal platelet rich plasma (PRP). However, this technique is highly dependent on the variability derived from the use of PRP (amount of coagulant factor-VIII, number of platelets, etc.). In an attempt to avoid these disadvantages, Bird's method has been modified by using standardized commercial reagents (lyophilized plasma with 100% factor-VIII coagulant activity, purified fibrinogen, and platelet Factor 3) instead of PRP. The sensitivity reaches 0.8 Bethesda units and the correlation with the Bethesda method is r = 0.964, p less than 0.001. This newly developed method is as simple as Bird's, and appears to be at least, as accurate and reproducible as the Bethesda method.

Detection of two different anti-factor VIII/von Willebrand factor antibodies of the IgA class in a hemophilic patient with a polyclonal factor VIII inhibitor of the IgG class.

A hemophilic patient treated with Factor VIII (F.VIII) concentrates developed a F.VIII inhibitory activity. The patient's plasma showed 2 anti-F.VIII/von Willebrand Factor (vWF) antibodies (Abs) of the IgG and IgA class respectively. The specific anti-F.VIII/vWF Abs were isolated and resulted to be IgG (20 micrograms/ml) and IgA (35 micrograms/ml). The plasma was subsequently fractionated by Protein A-Sepharose and the IgG and IgA containing fractions were separately analyzed for anti-F.VIII activity. Both fractions exhibited F.VIII inhibitory activity, but that corresponding to the IgA was lower than expected. Regarding the possible existence of a non-inhibitor Ab in the IgA containing sample, plasma was processed through an immunoadsorbent to which a F.VIII devoid vWF preparation had been previously coupled and further fractionated by Protein A-Sepharose, obtaining 2 IgA fractions. One of them exhibited F.VIII inhibitory activity while the other, which reacted with the F.VIII devoid vWF preparation, did not. Therefore, this latter one was considered as a true anti-vWF Ab. The IgG and IgA inhibitors were polyclonal and the IgG one was composed of the 4 IgG subclasses.

A modification of the APC resistance test and its application to the study of patients on coumarin therapy.

APC resistance appears to be caused, predominantly, by a mutation in coagulation factor V (nucleotide 1691: G to A). This phenomenon is usually studied by performing APTTs in the absence and presence of added APC. We studied a modification of the assay involving dilution of the test plasma in factor V deficient plasma, to render the assay more factor V specific. This modification was applied to 76 patients with venous thrombosis on coumarin treatment and to 45 controls. Two out of 45 controls (4.4%) showed abnormal results with the modified test. They also showed loss of factor V exon 10 Mnl I restriction site, associated to APC resistance. All remaining controls, with normal functional results by the modified assay, showed normal restriction profile. We detected 9 affected patients (11.8%), one of them homozygous or double heterozygous. In conclusion, the modified assay is very sensitive for factor V dependent APC resistance, and can successfully be applied to patients on coumarin therapy.

Functional compensation of the low platelet count by increased individual platelet size in a patient with May-Hegglin anomaly presenting with acute myocardial infarction.

Platelets are known to play a crucial role in normal hemostasis as well as in thrombus formation at sites exposed to blood flow, as in coronary thrombosis. Thus, low platelet count is a strong negative risk factor for the occurrence of arterial thrombosis, such as occurs in acute myocardial infarction. We encountered a patient with May-Hegglin anomaly, presenting with acute myocardial infarction in his sixth decade, even though his platelet counts had always been less than 50 x 10(3)/microl. We investigated the characteristics of his platelets under the effect of shearing and found that shear-induced platelet aggregation and binding of soluble von Willebrand factor (vWF) to platelets could be induced, even when the patient's platelet count was less than 10 x 10(3)/microl, but that virtually no aggregation or vWF binding by normal platelets could be induced by shearing when platelet counts were less than 50 x 10(3)/microl. We conclude that the low platelet counts in a patient with May-Hegglin anomaly can be functionally compensated for by larger individual platelets, in view of the vWF-dependent platelet thrombus formation occurring under the effect of blood flow and that that is why most patients with May-Hegglin anomaly do not have a bleeding tendency, even though their platelet counts are very low.

Safety procedures of coagulation factors.

Two main types of safety procedures must be applied to biological products, including plasma derivatives: (i) preventive procedures and (ii) elimination procedures. Prevention includes epidemiological control of donor populations; checks on each donor's health condition; analysis of each donation for the main pathogens using serological methods; additional analysis of all plasma for human immunodeficiency virus (HIV), hepatitis B virus (HBV), hepatitis C virus (HCV), hepatitis A virus (HAV) and the B19 virus, using nucleic acid amplification techniques (NAT). A 60 days or longer inventory hold of all plasma donations is applied, to allow additional time to discard previous donations from potential seroconverting or otherwise rejectable donors. Elimination procedures minimize the low residual risk of transmitting pathogens, including unknown or previously undetected ones. Since the introduction 20 years ago of solvent-detergent treatment, very effective against enveloped viruses (HIV, HBV, HCV, West Nile virus, SARS, avian influenza virus etc), there have been no known cases of transmission of this type of pathogens by products manufactured according to this procedure. Other inactivation procedures such as pasteurization, dry-heat or nanofiltration may prove equally effective. In addition, dry-heat treatment and nanofiltration are capable of effectively eliminating non-enveloped viruses (HAV, B19 virus). Recent studies show that the B19 virus is much more sensitive to heat (in lyophilized state or by pasteurization) and acid pH than previously thought. Although there is no evidence for the transmission of classic transmissible spongiform encephalopathies (TSEs) through blood or blood-products transfusion, four possible cases have been reported in the United Kingdom involving transmission by non-leukoreduced blood components of the agent that causes variant Creutzfeldt-Jakob Disease (vCJD), a disease linked to the outbreak of bovine spongiform encephalopathy (BSE) which took place in that country. However, there are no cases of human TSE (classic or variant) transmission by plasma-derived products. Analytical methods capable of detecting the vCJD agent in patients' brains (where high titres are found) and other tissues (such as the spleen, appendix and lymph nodes, where much lower concentrations are found) are unable to detect the agent in blood or plasma from patients with vCJD, even in the clinical phase of the disease. Experiments by Grifols and other groups show that the capacity of the production processes to eliminate vCJD agent models is many orders of magnitude greater than the maximum expected load of the agent. In this regard, the efficacy of precipitation, affinity chromatography, depth filtration and nanofiltration are particularly notable.

Effect of temperature on plasma freezing under industrial conditions.

The European Pharmacopoeia monograph on Human plasma for fractionation does not define the freezing process time but does define the freezing temperature (- 30 degrees C or below). Initial freezing conditions are crucial for the quality of plasma. These conditions were intended to preserve labile proteins such as fVIIl, but they can also be considered favourable for the plasma quality in general. This study evaluates the way the industrial plasma freezing affects labile coagulation factors. We have studied the freezing of plasma in industrial-size chambers at temperatures close to - 30 degrees C, - 25 degrees C and - 20 degrees C, and the possible differences between performing the freezing process in a chamber or in a freezer, in order to elucidate whether or not these parameters affect the quality of plasma. For this study, plasma bottles were frozen in industrial chambers set at - 30 degrees C, - 25 degrees C and - 20 degrees C, and in a freezer set at - 20 degrees C. The freezing rates were followed by means of probes in plasma control bottles. From this plasma, coagulation factors (fVIII, fIX and fibrinogen) were analysed before and after freezing, and cryoprecipitate was obtained in some cases. Statistically significant differences exist in fVIII:C recovery in thawed plasma between freezing at - 30 degrees C and at - 20 degrees C (n = 11; 85.4 +/- 4.3 % versus 74.6 +/- 6.0 % (chamber) or 79.3 +/- 6.3 % (freezer)). There is no difference between - 30 degrees C and - 25 degrees C, or between freezing at - 20 degrees C in a chamber or in a freezer. No significant loss of activity in thawed plasma is observed for fIX and fibrinogen at - 25 degrees C or - 20 degrees C versus - 30 degrees C. The fVIII and vWF recovery in cryoprecipitates does not show differences (464.2 IU fVIII/ml at - 30 degrees C, 446.7 IU fVIII/ml at - 25 degrees C, and 475.8 IU fVIII/ml at - 20 degrees C). The results obtained from this study support that plasma might also be frozen at - 25 degrees C or below without any impact on its quality, and that sporadic and short term deviations, from - 30 degrees C or below up to - 25 degrees C, in the currently required freezing temperature, would not have an effect on the labile factors recovery.

Possible alternative to European Pharmacopoeia's method of analysis Test for Fc Function of Immunoglobulin (2.7.9) by using tetanus toxoid as antigen.

Preparations of intravenous immunoglobulins must keep functional integrity throughout the purification process. In order to assess Fc fragment functionality, the European Pharmacopoeia proposes the Test for Fc function of immunoglobulin (2.7.9), which is based on a rubella antigen of high titre. Sometimes, such antigen is difficult to obtain. In the present study, we develop the same assay using tetanus toxoid instead of rubella antigen, adapting the procedure for the use of tetanus toxoid. The comparison between rubella-based and tetanus-based assays showed that the slopes of the haemolysis curves were higher if red blood cells had been sensitised with the rubella antigen than with tetanus toxoid. Nonetheless, the tetanus-based assay gave satisfactory results and it could be a good alternative antigen target.