Plasma-derived FVIII/VWF complex shows higher protection against inhibitors than isolated FVIII after infusion in haemophilic patients: A translational study.

INTRODUCTION: Presence of von Willebrand factor (VWF) in FVIII concentrates offers protection against neutralizing inhibitors in haemophilia A (HA). Whether this protection is more evident in plasma-derived (pd) FVIII/VWF or recombinant (r) FVIII concentrates remains controversial. AIM: We investigated the protection exerted by VWF against FVIII inhibitors in an in vivo mouse model of HA exposed to pdFVIII/VWF or to various rFVIII concentrates. METHODS: Haemophilia A mice received the different FVIII concentrates after administration of vehicle or an inhibitory IgG purified from a commercial pool of HA plasma with inhibitors and FVIII:C recoveries were measured. Furthermore, using a novel clinically oriented ex vivo approach, Bethesda inhibitory activities (BU) of a commercial pool of HA plasma with inhibitors were assessed using normal plasma, or plasma from severe HA patients, without inhibitors, after treatment with the same concentrates. RESULTS: in vivo studies showed that pdFVIII/VWF offers markedly higher protection against inhibitors when compared with any of the FVIII products without VWF. More importantly, in the ex vivo studies, plasma from patients treated with pdFVIII/VWF showed higher protection against inhibitors (P values ranging .05-.001) in comparison with that observed in plasma from patients who received FVIII products without VWF, regardless of the type of product evaluated. CONCLUSION: Data indicate that FVIII+VWF complexes assembled in the circulation after rFVIII infusion are not equivalent to the naturally formed complex in pdFVIII/VWF. Therefore, rFVIII infused into HA patients with inhibitors would be less protected by VWF than the FVIII in pdFVIII/VWF concentrates.

[The capacity of albumin to bind to beta-amyloid]. / Capacidad de unión de la albúmina al beta-amiloide.

INTRODUCTION: Most plasma beta-amyloid peptide (Alphabeta) has been described to circulate bound to albumin (approx. 90%). Moreover, a balance between peripheral and brain Alphabeta seems to exist, so a reduction of Alphabeta levels in blood through plasma exchange with therapeutic albumin should induce a clearance of brain Alphabeta. In this study, content of Alphabeta in therapeutic albumin as well as its binding capacity were characterized. MATERIALS AND METHODS: Levels of Alphabeta(1-40) and Alphabeta(1-42) were determined by means of ELISA technique in therapeutic albumin (human albumin Grifols; n = 18 batches), in normal plasma (n = 8) and in plasma from patients with Alzheimer disease (n = 45). Binding capacity of therapeutic albumin to synthetic peptides containing the primary sequence of human Alphabeta(1-42) was determined by means of surface plasmon resonance (SPR) technique. RESULTS. Both the Alphabeta(1-40) and Alphabeta(1-42) levels in therapeutic albumin were always lower than the last valid point measured in the standard curve (< 25 to < 63 pg/mL). Levels in normal plasma and in plasma from Alzheimer disease patients ranged between < 25 to 312 pg/mL for Alphabeta(1-40), and < 25 to 279,4 pg/mL for Alphabeta(1-42). SPR studies confirmed the high affinity of therapeutic albumin for the experimental Alphabeta peptide. CONCLUSIONS: Human albumin Grifols shows undetectable Alphabeta levels, and lower to those observed in normal plasma and in plasma from patients with Alzheimer disease. Moreover, it was able to bind peptides containing the sequence of human Alphabeta(1-42).

Capacidad de unión de la albúmina al beta-amiloide / The capacity of albumin to bind to beta-amyloid

Introducción. Se ha descrito que la mayor parte del péptido beta-amiloide (Ab) plasmático se halla unido a albúmina (aprox. 90%) y que parece existir un equilibrio entre el Ab periférico y el cerebral, por lo que debería ser posible reducir sus niveles en sangre mediante el recambio plasmático con albúmina terapéutica que, a su vez, podría influir en el desalojo de Ab cerebral. En este estudio se realizó una caracterización del contenido y la capacidad de unión de la albúmina terapéutica al Ab. Materiales y métodos. Niveles de Ab1-40 y Ab1-42 en albúmina terapéutica (albúmina humana Grifols; n = 18 lotes), así como en plasma normal (n = 8) o de pacientes con enfermedad de Alzheimer (n = 45), se determinaron mediante ELISA. La capacidad de unión de la albúmina terapéutica a péptidos sintéticos con la secuencia primaria del Ab1-42 humano se determinó mediante resonancia de plasmones de superficie (SPR). Resultados. Los niveles tanto de Ab1-40 como de Ab1-42 en la albúmina terapéutica fueron siempre inferiores al último punto válido de la curva estándar (< 25 a < 63 pg/ml). Los niveles en plasma normal o de pacientes con enfermedad de Alzheimer oscilaron entre < 25 y 312 pg/ml para Ab1-40 y < 25 y 279,4 pg/ml para Ab1-42. Los experimentos de SPR confirmaron una alta afinidad de la albúmina terapéutica por el péptido Ab experimental. Conclusiones. La albúmina humana Grifols presenta un contenido indetectable de Ab e inferior al observado en plasma de controles normales y pacientes con enfermedad de Alzheimer, y además es capaz de unirse a péptidos con la secuencia del Ab1-42 humano (AU)

Introduction. Most plasma beta-amyloid peptide (Ab) has been described to circulate bound to albumin (aprox. 90%). Moreover, a balance between peripheral and brain Ab seems to exist, so a reduction of Ab levels in blood through plasma exchange with therapeutic albumin should induce a clearance of brain Ab. In this study, content of Ab in therapeutic albumin as well as its binding capacity were characterized. Materials and methods. Levels of Ab1-40 and Ab1-42 were determined by means of ELISA technique in therapeutic albumin (human albumin Grifols; n = 18 batches), in normal plasma (n = 8) and in plasma from patients with Alzheimer disease (n = 45). Binding capacity of therapeutic albumin to synthetic peptides containing the primary sequence of human Ab1-42 was determined by means of surface plasmon resonance (SPR) technique. Results. Both the Ab1-40 and Ab1-42 levels in therapeutic albumin were always lower than the last valid point measured in the standard curve (< 25 to < 63 pg/mL). Levels in normal plasma and in plasma from Alzheimer disease patients rantransport ged between < 25 to 312 pg/mL for Ab1-40, and < 25 to 279,4 pg/mL for Ab1-42. SPR studies confirmed the high affinity of therapeutic albumin for the experimental Ab peptide. Conclusions. Human albumin Grifols shows undetectable Ab levels, and lower to those observed in normal plasma and in plasma from patients with Alzheimer diisease. Moreover, it was able to bind peptides containing the sequence of human Ab1-42 (AU)