Lorna M. Williamson

Recombinant human IgG molecules lacking Fcγ receptor I binding and monocyte triggering activities

Subclasses of human IgG have a range of activity levels with different effector systems but each triggers at least one mechanism of cell destruction. We are aiming to engineer non‐destructive human IgG constant regions for therapeutic applications where depletion of cells bearing the target antigen is undesirable. The attributes required are a lack of killing via Fcγ receptors (R) and complement but retention of neonatal FcR binding to maintain placental transport and the prolonged half‐life of IgG. Eight variants of human IgG constant regions were made with anti‐RhD and CD52 specificities. The mutations, in one or two key regions of the CH2 domain, were restricted to incorporation of motifs from other subclasses to minimize potential immunogenicity. IgG2 residues at positions 233 – 236, substituted into IgG1 and IgG4, reduced binding to FcγRI by 104‐fold and eliminated the human monocyte response to antibody‐sensitized red blood cells, resulting in antibodies which blocked the functions of active antibodies. If glycine 236, which is deleted in IgG2, was restored to the IgG1 and IgG4 mutants, low levels of activity were observed. Introduction of the IgG4 residues at positions 327, 330 and 331 of IgG1 and IgG2 had no effect on FcγRI binding but caused a small decrease in monocyte triggering.

Ten years of hemovigilance reports of transfusion‐related acute lung injury in the United Kingdom and the impact of preferential use of male donor plasma

BACKGROUND AND METHODS: From 1996 through 2006, 195 cases were reported as transfusion‐related acute lung injury (TRALI) to the Serious Hazards of Transfusion scheme and from 1999 onward classified by probability, using clinical features and HLA and/or HNA typing. From late 2003, the National Blood Service provided 80 to 90 percent of fresh‐frozen plasma (FFP) and plasma for platelet (PLT) pools from male donors.

Activation during preparation of therapeutic platelets affects deterioration during storage : a comparative flow cytometric study of different production methods

Three different separation methods, all using centrifugation, are routinely used to prepare therapeutic platelet concentrates from human donor blood. Platelet concentrates derived from platelet‐rich plasma (PRP‐PC), buffy coat (BC‐PC) and apheresis (AP‐PC) were investigated at the end of production, and over an 8 d storage period. Change in platelet surface markers were measured by flow cytometry, using fluorescein‐conjugated antibodies to fibrinogen, P‐selectin (CD62P), GPIIb–IIIa (CD41), GPIbα (CD42b) and GPV (CD42d), and fluorescein‐conjugated Annexin V was used to measure expression of anionic phospholipid.

Management and outcome of 200 cases of fetomaternal alloimmune thrombocytopenia

BACKGROUND: Fetomaternal alloimmune thrombocytopenia (FMAIT) is the commonest cause of severe thrombocytopenia in term neonates but its management remains controversial.

The Transfusion Alternatives Preoperatively in Sickle Cell Disease (TAPS) study: a randomised, controlled, multicentre clinical trial

BACKGROUND No consensus exists on whether preoperative blood transfusions are beneficial in patients with sickle-cell disease. We assessed whether perioperative complication rates would be altered by preoperative transfusion. METHODS We did a multicentre, randomised trial. Eligible patients were aged at least 1 year, had haemoglobin SS or Sβ(0)thalassaemia sickle-cell-disease subtypes, and were scheduled for low-risk or medium-risk operations. Patients were randomly assigned no transfusion or transfusion no more than 10 days before surgery. The primary outcome was the proportion of clinically important complications between randomisation and 30 days after surgery. Analysis was by intention to treat. FINDINGS 67 (96%) of 70 enrolled patients-33 no preoperative transfusion and 34 preoperative transfusion-were assessed. 65 (97%) of 67 patients had the haemoglobin SS subtype and 54 (81%) were scheduled to undergo medium-risk surgery. 13 (39%) of 33 patients in the no-preoperative-transfusion group had clinically important complications, compared with five (15%) in the preoperative-transfusion group (p=0.023). Of these, 10 (30%) and one (3%), respectively, had serious adverse events. The unadjusted odds ratio of clinically important complications was 3.8 (95% CI 1.2-12.2, p=0.027). 10 (91%) of 11 serious adverse events were acute chest syndrome (nine in the no-preoperative-transfusion group and one in the preoperative-transfusion group). Duration of hospital stay and readmission rates did not differ between study groups. INTERPRETATION Preoperative transfusion was associated with decreased perioperative complications in patients with sickle-cell disease in this trial. This approach could, therefore, be beneficial for patients with the haemoglobin SS subtype who are scheduled to undergo low-risk and medium-risk surgeries. FUNDING NHS Blood and Transplant.

The impact of universal leukodepletion of the blood supply on hemovigilance reports of posttransfusion purpura and transfusion‐associated graft‐versus‐host disease

BACKGROUND: The pathogenesis of posttransfusion purpura (PTP) and transfusion‐associated graft‐versus‐host disease (TA‐GVHD) involves patient exposure to donor platelets (PLTs) and T lymphocytes, respectively, which are removed during blood component leukodepletion (LD).

The quality of platelets after storage for 7 days

To prevent transfusion of platelet concentrates (PCs) contaminated with bacteria, testing may need to be performed on day 1 or 2, which will reduce their useful shelf life unless storage beyond 5 days, which is currently the standard in most countries, is permitted. Bacterial screening is being considered or implemented in a number of countries because contamination of PCs with bacteria causes significant morbidity and mortality. UK haemovigilance data for the period 1996–2001 show that of 38 transfusion-transmitted infections, 21 were caused by bacteria (17 associated with platelet components), six of which were fatal (Serious Hazards of Transfusion, 2002). Equally, risk-reduction strategies for immune complications such as transfusion-related acute lung injury and the unknown risk of variant Creutzfeldt– Jakob disease transmission act as a driver to replace as much plasma in PCs as possible with platelet additive solutions (PASs), and hence assessment of extended platelet storage in plasma or PAS has become a current topic of interest for many blood services. Storage of platelets for up to 7 days was permitted in the USA in the 1980s until 1986, when the Food and Drug Administration (FDA) reduced this to 5 days because of concerns over rates of bacterial contamination in PC towards the end of their shelf life. Some European countries now already routinely issue PCs to day 7 of storage where these are screened for bacterial contamination. This review focuses on the effect extending the storage of PCs to 7 days has on platelet quality, without pathogenreduction technology. Methods of preparing PCs vary between countries and indeed within a country. PCs can be prepared by centrifugation of whole blood by either the plateletrich plasma (PRP) method, favoured in North America, or the buffy coat (BC) method, favoured by most European countries. Alternatively, PCs can be collected by several apheresis techniques. PCs from any production method are stored in 100% plasma or a proportion of plasma (typically 65%) may be replaced with a PAS. Additionally, differences such as the choice of anticoagulant, length of time and temperature at which blood is held prior to processing, whether PCs are leucocyte depleted (LD) or not, the volume and concentration of platelets in the PCs, the media in which PCs are stored and type of storage container may all influence the results obtained. Care should be taken not to generalize the results of one study to PCs prepared using different processing conditions. Before considering data on the quality of PCs during extended storage, we must appreciate the difficulty of predicting their efficacy in vivo from the results of laboratory testing. This has been extensively reviewed elsewhere (Murphy et al., 1994; Holme, 1998; Williamson, 1998; FDA Guidance, 1999; Rinder & Smith, 2003). Essentially, there are four lines of evidence to assess the quality of PCs: tests of platelet function and metabolism in vitro, animal models of thrombocytopenia, recovery and survival of labelled autologous platelets in normal volunteers and platelet increment studies in thrombocytopenic patients. Very few tests of platelet function performed on PCs in vitro correlate with platelet viability (recovery or lifespan) after transfusion in healthy volunteers, and none has been adequately validated in patients after transfusion. Tests that do correlate with viability, as shown by some, but not all, investigators, include the morphology score (percentage of platelets that are discoid or spheroid), the hypotonic shock response (HSR), extent of shape change (ESC) and platelet adenosine triphosphate (ATP) levels (Slichter, 1981; Holme, 1998). pH values below 6 0–6 2 are associated with poor in vivo recovery Correspondence: Dr Rebecca Cardigan, National Blood Service, Long Road, Cambridge CB2 2PT, UK. Tel.: þ44 1223 548085; fax: þ44 1223 548136; e-mail: rebecca.cardigan@nbs.nhs.uk Transfusion Medicine, 2003, 13, 173–187

The role of prophylactic fresh frozen plasma in decreasing blood loss and correcting coagulopathy in cardiac surgery. A systematic review

Fresh frozen plasma is commonly used in cardiac surgery in an attempt to replace clotting factors and to decrease bleeding. Despite this, there has been no previous review of the available literature to support this practice. The aim of this review was to study the effect of prophylactic peri‐operative transfusion of fresh frozen plasma on bleeding and coagulopathy in patients undergoing cardiac surgery. A comprehensive literature search was performed and all randomised controlled trials of the use of fresh frozen plasma in cardiac surgery were included. Six small trials were found that included a total of 363 participants with six different dose regimens of fresh frozen plasma. The overall quality of the studies was poor due to small patient numbers and lack of allocation concealment. There was no evidence that the prophylactic use of fresh frozen plasma affected peri‐operative blood loss in cardiac surgery. There was some evidence that it may improve platelet count and fibrinogen concentration.

The quality of fresh-frozen plasma produced from whole blood stored at 4°C overnight

BACKGROUND: The aim of this study was to assess whether the quality of FFP produced from whole blood stored at 4°C overnight is adequate for its intended purpose.

The effect of universal leukoreduction on postoperative infections and length of hospital stay in elective orthopedic and cardiac surgery.

BACKGROUND: A before and after study was under‐ taken to investigate the effect of universal leukoreduction (ULR) in the UK on postoperative length of hospital stay (LOS) and infections.