Harnessing the potential of data-driven strategies to optimise transfusion practice.

No one doubts the significant variation in the practice of transfusion medicine. Common examples are the variability in transfusion thresholds and the use of tranexamic acid for surgery with likely high blood loss despite evidence-based standards. There is a long history of applying different strategies to address this variation, including education, clinical guidelines, audit and feedback, but the effectiveness and cost-effectiveness of these initiatives remains unclear. Advances in computerised decision support systems and the application of novel electronic capabilities offer alternative approaches to improving transfusion practice. In England, the National Institute for Health and Care Research funded a Blood and Transplant Research Unit (BTRU) programme focussing on 'A data-enabled programme of research to improve transfusion practices'. The overarching aim of the BTRU is to accelerate the development of data-driven methods to optimise the use of blood and transfusion alternatives, and to integrate them within routine practice to improve patient outcomes. One particular area of focus is implementation science to address variation in practice.

Major haemorrhage: past, present and future.

Major haemorrhage is a leading cause of morbidity and mortality worldwide. Successful treatment requires early recognition, planned responses, readily available resources (such as blood products) and rapid access to surgery or interventional radiology. Major haemorrhage is often accompanied by volume loss, haemodilution, acidaemia, hypothermia and coagulopathy (factor consumption and fibrinolysis). Management of major haemorrhage over the past decade has evolved to now deliver a 'package' of haemostatic resuscitation including: surgical or radiological control of bleeding; regular monitoring of haemostasis; advanced critical care support; and avoidance of the lethal triad of hypothermia, acidaemia and coagulopathy. Recent trial data advocate for a more personalised approach depending on the clinical scenario. Fresh frozen plasma should be given as early as possible in major trauma in a 1:1 ratio with red blood cells until the results of coagulation tests are available. Tranexamic acid is a cheap, life-saving drug and is advocated in major trauma, postpartum haemorrhage and surgery, but not in patients with gastrointestinal bleeding. Fibrinogen levels should be maintained > 2 g.l-1 in postpartum haemorrhage and > 1.5 g.l-1 in other haemorrhage. Improving outcomes after major traumatic haemorrhage is now driving research to include extending blood-product resuscitation into prehospital care.

The effect of iron deficiency and anaemia on women's health.

Iron deficiency and anaemia are global health problems and major causes of morbidity in women. Current definitions of anaemia in women are historic and have been challenged by recent data from observational studies. Menstrual loss, abnormal uterine bleeding and pregnancy put women at risk of developing iron deficiency which can result in severe fatigue, reduced exercise capacity and poor work performance. Iron deficiency and anaemia during pregnancy are associated with adverse maternal and fetal outcomes, including neurocognitive deficits in children born to iron-deficient mothers. Both iron deficiency and anaemia are common in women undergoing surgery but their association with poor outcomes remains uncertain. The enduring burden of iron deficiency and anaemia in women suggests that current strategies for recognition, prevention and treatment are limited in their utility. Improvements in our understanding of iron homeostasis and the development of new iron preparations, which are better absorbed with fewer side-effects, may improve therapeutic effectiveness of oral iron. Intravenous iron is efficacious for correcting anaemia rapidly but high-quality data on patient-centred outcomes and cost-effectiveness are currently lacking. Many recommendations for the treatment of iron deficiency and anaemia in national guidelines are not supported by high-quality evidence. There is a need for robust epidemiological data and well-designed clinical trials. The latter will require collaborative working between researchers and patients to design studies in ways that incorporate patients' perspectives on the research process and target outcomes that matter to them.

The association of pre-operative anaemia with morbidity and mortality after emergency laparotomy.

Pre-operative anaemia is associated with poor outcomes after elective surgery but its relationship with outcomes after emergency surgery is unclear. We analysed National Emergency Laparotomy Audit data from 1 December 2013 to 30 November 2017, excluding laparotomy for haemorrhage. Anaemia was classified as 'mild' 129-110 g.l-1; 'moderate' 109-80 g.l-1; or 'severe' ≤ 79 g.l-1. The primary outcome was 90-day mortality. Secondary outcomes were 30-day mortality, return to theatre and postoperative hospital stay. The primary outcome was available for 86,763 patients, of whom 45,306 (52%) were anaemic. There were 12,667 (15%) deaths at 90 postoperative days and 9246 (11%) deaths at 30 postoperative days. Anaemia was associated with increased 90-day and 30-day mortality, odds ratio (95%CI): mild, 1.15 (1.09-1.21); moderate, 1.44 (1.36-1.52); and severe, 1.42 (1.24-1.63), p < 0.001 for all; mild, 1.07 (1.00-1.12), p = 0.030; moderate, 1.30 (1.21-1.38), p < 0.001; and severe, 1.22 (1.05-1.43), p = 0.010, respectively. All categories of anaemia were associated with prolonged hospital stay, adjusted coefficient (95%CI): mild, 1.31 (1.01-1.62); moderate, 3.41 (3.04-3.77); severe, 2.80 (1.83-3.77), p < 0.001 for all. Moderate and severe anaemia were associated with increased risk of return to the operating theatre, odds ratio (95%CI): moderate 1.13 (1.06-1.21), p < 0.001; and severe 1.23 (1.06-1.43), p = 0.006. Pre-operative anaemia is common in patients undergoing emergency laparotomy and is associated with increased postoperative mortality and morbidity.

A multicentred study to validate a consensus bleeding assessment tool developed by the biomedical excellence for safer transfusion collaborative for use in patients with haematological malignancy.

BACKGROUND: There continues to be uncertainty about the optimal approach to documenting bleeding data in platelet transfusion trials, with a desire to apply a common assessment tool across all trials. With this in mind, a consensus bleeding assessment tool (BAT) has been developed by the Biomedical Excellence for Safer Transfusion (BEST) collaborative, based on review of data collection forms used in published randomized trials and following content validation with a range of healthcare professionals at seven haematology centres through BEST members. This study aimed to evaluate reliability and reproducibility of the consensus BAT. METHODS: Replicated clinical assessments of bleeding were undertaken by participants with haematological malignancies recruited at four haematology centres in an international, multicentred, observational study. Concordance of repeat assessments was calculated for agreement in site and grade of bleeding observed. RESULTS: Forty patients consented to participate, and 13 trained bleeding assessors collected these data. Bleeding assessments were carried out on 113 separate days. Of all 225 bleeding assessments, 204 were compared for grade concordance, and 160 were compared for site concordance. There was very good grade concordance (83%, 95% confidence interval 74-93%) and good bleeding site concordance (69%, 95% confidence interval 57-79%) in observations of bleeding. Discordance was primarily in relation to assessing skin bleeding. CONCLUSIONS: Alongside a structured training programme, levels of concordance for a consensus BAT were high. Researchers using assessment tools for bleeding need to balance comprehensive data collection against potential loss of accuracy for some types of bleeding, such as skin findings.

Thromboelastography may predict risk of grade 2 bleeding in thrombocytopenic patients.

BACKGROUND AND OBJECTIVES: Platelet count is used as a prophylactic platelet transfusion trigger, although evidence suggests that it is a poor predictor of bleeding. Thus, alternative tests are required. The primary objective of this study was to compare thromboelastography (TEG) parameters on days with and without bleeding symptoms. The secondary objectives were to investigate the relationship between TEG parameters and haematological variables, fever, C-reactive protein (CRP) and platelet transfusion. MATERIALS AND METHODS: This is a prospective, observational pilot study of 13 thrombocytopenic, haemato-oncologic patients, over 17 cycles of chemotherapy. Bleeding assessment was performed daily together with a total platelet count (TPC), reticulated platelet per cent (RPP) and count (RPC), haemoglobin, mean platelet volume, white blood cell count (WBC), CRP and temperature. TEG analyses were performed on weekdays. RESULTS: TEG alpha angle was significantly lower on days with World Health Organization (WHO) grade 2 bleeding than on days without bleeding. Haematologic variables, CRP and platelet transfusion the previous day were associated with the outcome of TEG analysis, but fever was not. CONCLUSION: We found a highly significant correlation between the TEG alpha angle and WHO grade 2 bleeding. This finding suggests that fibrinogen-platelet interactions may affect the bleeding risk in thrombocytopenic patients.

Desmopressin for treatment of platelet dysfunction and reversal of antiplatelet agents: a systematic review and meta-analysis of randomized controlled trials.

Essentials The optimal management of patients with platelet dysfunction undergoing surgery is unclear. This meta-analysis compared perioperative administration of desmopressin to placebo. Desmopressin reduced red cell transfusions, blood loss and risk of re-operation due to bleeding. There were too few events to determine if there was a change in the risk of thrombotic events. SUMMARY: Background Platelet dysfunction, including that caused by antiplatelet agents, increases the risk of perioperative bleeding. The optimal management of patients with platelet dysfunction undergoing surgery is unclear. Objectives To assess whether desmopressin reduces perioperative allogeneic red cell transfusion and bleeding in patients with platelet dysfunction. Patients/Methods We searched for randomized controlled trials in The Cochrane Central Register of Controlled Trials, MEDLINE, PubMed, Embase, the Transfusion Evidence Library and the ISI Web of Science to 7th July 2016. Data were pooled using mean difference (MD), relative risks or Peto odds ratios (pOR) using a random-effects model. Results Ten trials with 596 participants were identified, all in the setting of cardiac surgery. Platelet dysfunction was due to antiplatelet agents in six trials and cardiopulmonary bypass in four trials. Patients treated with desmopressin were transfused with fewer red cells (MD, -0.65 units; 95% Confidence Interval [CI], -1.16 to -0.13 units), lost less blood (MD, -253.93 mL; 95% CI, -408.01 to -99.85 mL) and had a lower risk of re-operation due to bleeding (pOR, 0.39; 95% CI, 0.18-0.84). The GRADE quality of evidence was very low to moderate, suggesting considerable uncertainty over the results Conclusions Desmopressin may be a useful agent to reduce bleeding and transfusion requirements for people with platelet dysfunction or with a history of recent antiplatelet drug administration undergoing cardiac surgery.

Mortality from trauma haemorrhage and opportunities for improvement in transfusion practice.

BACKGROUND: The aim of this study was to describe the prevalence, patterns of blood use and outcomes of major haemorrhage in trauma. METHODS: This was a prospective observational study from 22 hospitals in the UK, including both major trauma centres and smaller trauma units. Eligible patients received at least 4 units of packed red blood cells (PRBCs) in the first 24 h of admission with activation of the massive haemorrhage protocol. Case notes, transfusion charts, blood bank records and copies of prescription/theatre charts were accessed and reviewed centrally. Study outcomes were: use of blood components, critical care during hospital stay, and mortality at 24 h, 30 days and 1 year. Data were used to estimate the national trauma haemorrhage incidence. RESULTS: A total of 442 patients were identified during a median enrolment interval of 20 (range 7-24) months. Based on this, the national incidence of trauma haemorrhage was estimated to be 83 per million. The median age of patients in the study cohort was 38 years and 73·8 per cent were men. The incidence of major haemorrhage increased markedly in patients aged over 65 years. Thirty-six deaths within 24 h of admission occurred within the first 3 h. At 24 h, 79 patients (17·9 per cent) had died, but mortality continued to rise even after discharge. Patients who received a cumulative ratio of fresh frozen plasma to PRBCs of at least 1 : 2 had lower rates of death than those who received a lower ratio. There were delays in administration of blood. Platelets and cryoprecipitate were either not given, or transfused well after initial resuscitation. CONCLUSION: There is a high burden of trauma haemorrhage that affects all age groups. Research is required to understand the reasons for death after the first 24 h and barriers to timely transfusion support.

Evidence and triggers for the transfusion of blood and blood products.

Allogeneic red cell transfusion is a commonly used treatment to improve the oxygen carrying capacity of blood during the peri-operative period. Increasing arterial oxygen content by increasing haemoglobin does not necessarily increase tissue oxygen delivery or uptake. Although the evidence-base for red cell transfusion practice is incomplete, randomised studies across a range of clinical settings, including surgery, consistently support the restrictive use of red cells, with no evidence of benefit for maintaining patients at higher haemoglobin thresholds (liberal strategy). A recent meta-analysis of 7593 patients concluded that a restrictive transfusion strategy was associated with a reduced risk of healthcare-associated infections (pneumonia, mediastinitis, wound infection, sepsis) when compared with a liberal transfusion strategy. The degree to which the optimal haemoglobin concentration or transfusion trigger should be modified for patients with additional specific risk factors (e.g. ischaemic heart disease), remains less clear and requires further research. Although most clinical practice guidelines recommend restrictive use of red cells, and many blood transfusion services have seen marked falls in overall usage of red cells, the use of other blood components such as fresh frozen plasma, platelets, and cryoprecipitate has risen. In clinical practice, administration of fresh frozen plasma is usually guided by laboratory tests of coagulation, mainly prothrombin time, international normalised ratio and activated partial thromboplastin time, but the predictive value of these tests to predict bleeding is poor.

Platelet transfusions for patients with haematological malignancies: who needs them?

The goal of platelet transfusions is to prevent severe and life-threatening bleeding in patients with thrombocytopenia. This aim needs to be balanced against the risks associated with platelet transfusions as well as the challenge of maintaining an adequate supply. This review summarizes the recent evidence regarding the clinical use of platelet transfusions in haematology patients, concentrating on the topics that still continue to provoke debate. These include the optimal dose for platelet transfusions and the relative safety of a 'therapeutic only' platelet transfusion strategy compared to the use of prophylactic platelet transfusions. The type of platelet product has been the subject of two recent systematic reviews. The results of these reviews will be discussed as well as their implications for current practice.

Transfusion practice and safety: current status and possibilities for improvement.

Audits of practice and incident reporting, most notably to national haemovigilance schemes, indicate that poor hospital transfusion practice is frequent and occasionally results in catastrophic consequences for patients. Improvements in practice are needed and depend on a combined approach including a better understanding of the causes of errors; a reduction in the complexity of routine procedures taking advantage of new technology systems, which enforce agreed guidelines and policies; the setting and regular monitoring of performance standards for key aspects of the hospital transfusion process, improved organisation of transfusion in hospitals and staff training; and further research on the safe and effective use of blood and alternatives to donor blood. There needs to be a greater recognition that 'transfusion safety' applies to the hospital transfusion process as well as the contents of blood bags and that resources need to be provided for the improvement of transfusion safety and management in hospitals commensurate to their importance.

Evidence for indications of fresh frozen plasma.

There continues to be a general but unfounded enthusiasm for fresh frozen plasma (FFP) usage across a range of clinical specialties in hospital practice. Clinical use of plasma has grown steadily over the last two decades in many countries. In England and Wales, there has not been a significant reduction in the use of FFP over the last few years, unlike red cells. There is also evidence of variation in usage among countries--use in England and Wales may be proportionately less per patient than current levels of usage in other European countries and the United States. Plasma for transfusion is most often used where there is abnormal coagulation screening tests, either therapeutically in the face of bleeding, or prophylactically in non-bleeding subjects prior to invasive procedures or surgery. Little evidence exists to inform best therapeutic plasma transfusion practice. Most studies have described plasma use in a prophylactic setting, in which laboratory abnormalities of coagulation tests are considered a predictive risk factor for bleeding prior to invasive procedures. The strongest randomised controlled trial (RCT) evidence indicates that prophylactic plasma for transfusion is not effective across a range of different clinical settings and this is supported by data from non-randomised studies in patients with mild to moderate abnormalities in coagulation tests. There are also uncertainties whether plasma consistently improves the laboratory results for patients with mild to moderate abnormalities in coagulation tests. There is a need to undertake new trials evaluating the efficacy and adverse effects of plasma, both in bleeding and non-bleeding patients, to understand whether the "presumed" benefits outweigh the "real risks". In addition, new haemostatic tests should be validated which better define risk of bleeding.

Feasibility and usefulness of self-assessment of bleeding in patients with haematological malignancies, and the association between platelet count and bleeding.

BACKGROUND AND OBJECTIVES: The aim of this study was to evaluate the collection of daily prospective information about bleeding outcomes in patients with thrombocytopenia, including information obtained by patient self-assessment. MATERIALS AND METHODS: Consecutive patients with haematological malignancies were enrolled in a study of bleeding data collection during the period of thrombocytopenia. A short educational session and information sheet was designed for self-assessment. Platelet counts and all transfusions were recorded daily. Bleeding scores were translated into World Health Organization (WHO) bleeding grades. RESULTS: Nineteen patients were included in the study. Four-hundred and ten days of thrombocytopenia were eligible for assessment of bleeds. Self-assessment was feasible, as defined by the total proportion of days on which self-assessment was completed (70%, 288 thrombocytopenic days). There was 86% agreement between bleeding data collected by self-assessment and by medical examination using a structured assessment form. Examples of discrepancies included the duration of petechiae/bruises and the reporting of minor bleeding. There was no evidence for an association between patients' morning platelet count and daily WHO bleeding grade. The incidences of WHO grade 1 and grade 2 bleeding on days with platelet counts < or = 10 x 10(9)/l, 11-20 x 10(9)/l, and > 20 x 10(9)/l were similar and did not reveal higher rates of bleeding at lower counts. CONCLUSIONS: Patient self-assessment can help to support comprehensive daily prospective monitoring of bleeding, specifically facilitating data collection following hospital discharge. The discrepancies between self-assessment and medical examination highlight the need to develop a validated international assessment tool. The association among platelet count, risk of bleeding and role of prophylactic platelet transfusions needs further evaluation in larger prospective trials.

Platelet transfusion prophylaxis for patients with haematological malignancies: where to now?

National guidelines for platelet transfusion in many countries recommend that the general platelet transfusion trigger for prophylaxis is 10x10(9)/l. This annotation reviews the evidence for this threshold level and discusses other current unresolved issues relevant to platelet transfusion practice such as the optimal dose and the clinical benefit of a strategy for the prophylactic use of platelet transfusions when the platelet count falls below a given threshold.

Prophylactic platelet transfusion for haemorrhage after chemotherapy and stem cell transplantation.

BACKGROUND: Platelet transfusions are used in modern clinical practice to prevent and treat bleeding in thrombocytopenic patients with bone marrow failure. Although considerable advances have been made in platelet transfusion therapy in the last 30 years, some areas continue to provoke debate, especially the use of prophylactic platelet transfusions for the prevention of thrombocytopenic bleeding. OBJECTIVES: To determine the optimal use of platelet transfusion for the prevention of haemorrhage (prophylactic platelet transfusion) in patients with haematological malignancies undergoing chemotherapy or stem cell transplantation. SEARCH STRATEGY: Randomised controlled trials (RCTs) were searched for in the Cochrane Central Register of Controlled Trials (CENTRAL). Searching was also undertaken on the OVID versions of MEDLINE and EMBASE using an RCT search filter strategy. SELECTION CRITERIA: Randomised controlled trials involving transfusions of platelet concentrates, prepared either from individual units of whole blood or by apheresis, and given prophylactically to prevent bleeding in patients with haematological malignancies and receiving treatment with chemotherapy and/or stem cell transplantation. DATA COLLECTION AND ANALYSIS: All electronically derived citations and abstracts of papers identified by the review search strategy were initially screened for relevancy by one reviewer. Studies clearly irrelevant were excluded at this stage. The full text of all potentially relevant trials was then formally assessed for eligibility by two reviewers independently. Two reviewers completed data extraction independently. Missing data were requested from the original investigators, as appropriate. Disagreements were resolved by discussion with the other reviewers. MAIN RESULTS: Eight completed published trials, with a total of 390 participants in the intervention groups and 362 participants in the control groups, were included in the review for further analysis. The eight studies were classified as: * three trials relevant to prophylactic platelet transfusions versus therapeutic platelet transfusions; * three trials relevant to prophylactic platelet transfusion with one trigger level versus prophylactic platelet transfusion with another trigger level; * two trials relevant to prophylactic platelet transfusion with one dose schedule versus prophylactic platelet transfusion with another dose schedule. The few reports of controlled trials addressing prophylactic versus therapeutic transfusions contained small numbers of patients and were all undertaken over 25 years ago. None of these three studies explicitly clarified whether the lack of a reported difference was a reflection of insufficient power in the trials. The findings of the meta-analyses for this group of three small studies must be interpreted with caution. In contrast, more contemporary trials addressed the question of what platelet count thresholds should apply for prophylactic transfusion; three identified studies broadly compared platelet transfusion thresholds of 10 versus 20 x 109/litre for different clinical groups of patients. There were no statistically significant differences between the groups with regards to mortality, remission rates, number of participants with severe bleeding events or red cell transfusion requirements. However, it was unclear whether the studies had sufficient power to demonstrate in combination non-inferiority in terms of safety of the lower threshold, 10 x 109/litre. Insufficient randomised trials have been undertaken to make clinically relevant conclusions about the effect of different platelet doses. REVIEWERS' CONCLUSIONS: There are no reasons to change current practice but uncertainty about the practice of prophylactic transfusion therapy should be recognised, particularly in the light of concerns about the scenario that blood products, including platelets, could become an increasingly scarce resource in the future and for which adequate alternatives do not exist. Consideration should be given to developing adequately powered trials comparing strategies of prophylaxis versus therapeutic platelet transfusion.

Which groups of patients are transfused? A study of red cell usage in London and southeast England.

BACKGROUND AND OBJECTIVES: There are few published data on the use of red blood cells (RBC) by specialty in the United Kingdom. The aim of this survey was to identify major specialty users of blood to target for audit of transfusion practice with a view to minimizing inappropriate use and to support planning of blood supply needs for the future. MATERIALS AND METHODS: Data were collected retrospectively of RBC units transfused at 62 hospitals/trusts in London and southeast England between April 1997 and March 1998. RESULTS: A total of 594 810 transfused RBC units were successfully traced to their respective clinical specialties, representing 91.9% of all RBC units issued to the study hospitals. Of the RBC units transfused, 51.2% were transfused in surgical, 36.0% in medical and 12.8% in "combined" specialties. CONCLUSIONS: This large study has accurately documented the clinical disciplines that are significant users of RBCs in our service area. It has heightened general understanding of RBC usage within hospitals. It has also raised questions on future strategies for reducing allogeneic blood transfusion that will be important if anticipated major reductions in blood supply occur in the near future.

Stem cells: progress in research and edging towards the clinical setting.

Mouse embryonic stem cells have been shown to differentiate into a variety of tissues in vitro and in transplantation experiments can produce many different cell types. Multipotent stem cells in adult humans have also shown a high degree of plasticity: haemopoietic stem cells, for example, have been shown to contribute to several other tissues, such as liver. From these simple observations there has been considerable extrapolation into the use of such putative totipotent stem cells in the clinical setting, with the development of 'designer' tissue engineering, whose aim is to create large tissues or even whole organs for clinical use. In practical terms, however, there are many limitations and difficulties and clinical use has been restricted to a very few settings, eg the use of fetal cells in Parkinson's disease. Nonetheless, there is enormous potential in this area, and also in the application of embryonic or adult stem cells as carriers for gene therapy; but the limitations of such treatment, in particular the stability of manipulated cells, and the problems of ageing and Ooncogenicity, not to mention a host of ethical and regulatory issues, all need to be considered.

A UK survey of virological testing of cadaver tissue donors. Microbiology Working Group of the NIBSC steering group on Tissue/Cell Banking and Engineering.

OBJECTIVES: To analyse information about virological testing of cadaveric tissue donors, including the kits used and the rates of test reactivity. MATERIALS AND METHODS: Retrospective data were collected using a standardised questionnaire sent to 16 tissue banks in the UK. The rates of repeat reactive screen tests and confirmed positive results for the markers HBsAg, anti-HCV, anti-HIV were analysed in 1,833 cadaver tissue donors tested at 12 tissue banks over one year up to March 1998. RESULTS: There was a wide range of kits in use for virological screen testing of cadaver donors. The rates of repeat reactivity in the screen tests varied from 0 to 42%. CONCLUSION: The findings have implications for policies based on discard of tissues from donors with repeat reactive results, and raise important safety issues with regards to cadaveric virological testing, as the test systems in use have not been validated for cadaver blood samples.

Treatment of Felty's syndrome with the haemopoietic growth factor granulocyte colony-stimulating factor (G-CSF).

Felty's syndrome (FS) (rheumatoid arthritis with neutropenia and splenomegaly) has a poor prognosis, largely because of the high risk of severe infection. Granulocyte colony-stimulating factor (G-CSF) is an emerging treatment for chronic neutropenia. We prospectively monitored its use in eight patients with recurrent infections or who required joint surgery. Significant side-effects were documented in five, including nausea, malaise, generalized joint pains, and in one patient, a vasculitic skin rash. In two patients treatment had to be stopped, and in these cases G-CSF had been started at full vial dosage (300 micrograms/ml filgrastim or 263 micrograms/ml lenograstim) alternate days or daily. G-CSF treatment was continued in three patients by restarting at reduced dose, and changing the proprietary formulation. G-CSF raised the neutrophil count, reduced severe infection, and allowed surgery to be performed. A combined clinical and laboratory index suggested that long-term treatment (up to 3.5 years) did not exacerbate the arthritis. Once on established treatment, it may be possible to use smaller weekly doses of G-CSF to maintain the same clinical benefit. One of the three patients whose FS was associated with a large granular T-cell lymphocytosis showed a reduction in this subset of lymphocytes during G-CSF treatment.

Gene expression in somatic cell hybrids derived from embryonic mice transgenic for human globin genes.

Somatic cell hybrids have been used previously to investigate the developmental regulation of globin gene expression. When a chromosome containing an active human fetal gamma gene is transferred to mouse erythroleukaemia (MEL) cells by cell fusion, there is persistent expression of this gene through multiple hybrid-cell divisions despite the 'adult' trans-acting factor environment of the MEL cell. We analysed hybrids formed between embryonic erythroblasts and MEL cells to determine whether the embryonic globin genes would be similarly regulated. Surprisingly, there was no detectable expression of either the endogenous (epsilon, beta h 1) or the transgenic (human epsilon) embryonic beta-like genes in a large number of hybrid pools and clones, even though these genes were expressed in the donor cells at the time of fusion. In contrast, the human gamma gene, which is also expressed as an embryonic gene in transgenic mice, continued to be expressed in these hybrids. This lack of embryonic gene expression in hybrids also applied to the alpha gene cluster; no mouse or human zeta mRNA was detectable in embryonic cell hybrids from mice transgenic for the human alphaglobin genes. Hybrids generated from embryonic non-erythroid cells resulted in expression that was largely restricted to the adult beta gene. It has previously been suggested that epigenetic modifications to the beta-globin gene cluster during normal development are responsible for the perpetuation of gamma and beta gene expression in this hybrid cell system. The results presented here suggest that no such stable modifications occur around the embryonic genes and therefore that the regulatory mechanisms determining embryonic globin gene transcription differ from those responsible for the expression of gamma and beta genes in this system.