Rare and transient anti-D antibody response in D(-) liver transplant recipients transfused with D(+) red blood cells.

A retrospective analysis was conducted on 20 D(-) liver transplant (LT) recipients transfused with D(+) RBCs perioperatively and screened for RBC antibodies between 2 and 6 months later. None developed anti-D detectable by the indirect antiglobulin test. Two patients produced weak anti-D that reacted only with papain-treated RBCs at 10 and 11 days without any sign of immune haemolysis. Antibodies became quickly undetectable. These data suggest an unusual pattern of alloimmunization in LT recipients with rapid, weak and transient antibody response and support the safety of transfusing D(+) RBCs in most of D(-) patients during LT surgery.

The use of rituximab to prevent severe delayed haemolytic transfusion reaction in immunized patients with sickle cell disease.

BACKGROUND: Delayed haemolytic transfusion reaction (DHTR) is mainly caused by an immune response to transfused red blood cells (RBCs). Immunized patients have a high risk of producing antibodies in response to further transfusion. Controlling the immune response to RBCs is therefore a major goal in sickle cell disease (SCD). STUDY DESIGN: We report an observational study of eight alloimmunized SCD patients with history of severe DHTR who were treated with rituximab before a new transfusion to prevent further immunization and DHTR. RESULTS: Five patients showed a good clinical outcome following transfusion preceded by preemptive treatment with rituximab. The remaining patients presented mild DHTR. In all patients, the results of post-transfusion screening tests were identical to those of pretransfusion tests; no newly formed antibodies were detected. CONCLUSION: These cases suggest that rituximab prevents at least occurrence of newly formed antibodies in high responders and minimizes the risk of severe DHTR. This study confirms that DHTR is complex in SCD and does not rely only on the classical antigens/antibodies conflict. Considering potentially serious adverse effect of rituximab, this treatment should be considered cautiously, and only when transfusion is absolutely necessary in patients with history of severe DHTR linked to immunization.

[Blood donor hemovigilance: impact for donor and recipient safety]. / Hémovigilance donneur: quel apport pour la sécurité du donneur et du receveur.

Since its creation in 1993, hemovigilance has an important place for blood safety. The part concerning donors, as the name suggests, targeted on improvement of donor's safety covers in fact the two points of the transfusion chain with serious adverse events in donor, epidemiologic survey for recipients and post-donation information on the two sides. Organized management and close collaboration between the actors of the transfusion chain are necessary to ensure the effectiveness of the system.

[Thrombocytopenia and pregnancy]. / Thrombopénie et grossesse.

The occurrence of thrombocytopenia during pregnancy is frequent (about 10%). Etiologies of thrombocytopenia are dominated by the gestational thrombocytopenia (>75%), which requires no exploration and no specific treatment; it usually occurs during the last trimester of pregnancy and corrects itself spontaneously after delivery. Other etiologies are: (1) immune thrombocytopenia (ITP) either primary or associated with other pathologies; ITP may appear early in the first trimester of pregnancy, (2) thrombotic microangiopathy syndromes, and (3) obstetric thrombocytopenia: eclampsia and HELLP syndrome (hemolysis elevated liver enzymes, and low platelet count). Treatment of pre-eclampsia and HELLP syndrome is based on resuscitative measures and symptomatic fetal extraction that will be discussed according to the term and severity of the case. The treatment of microangiopathy is based on resuscitation and plasma exchange. For ITP, no specific action is needed during pregnancy and only symptomatic patients with a platelet count less than 30×10(9)/L must receive a treatment. It is important to prepare the childbirth that can be vaginally except if there is an obstetric contraindication. A platelet count of 50×10(9)/L is required for the delivery, and of 75×10(9)/L in case of spinal anesthesia. Treatment implies a short course of corticosteroids associated with infusion of immunoglobulins in the most severe forms or in case of steroids resistance. There is a risk of neonatal thrombocytopenia requiring a control of the blood count for the baby at birth and within 5 days, newborns have to be treated if the platelet count is less than 20×10(9)/L.

[Mesenchymal stromal cells: Biological properties and clinical prospects]. / Cellules stromales mésenchymateuses : propriétés biologiques et perspectives thérapeutiques.

Mesenchymal stromal cells are defined as non-hematopoietic progenitors characterised by their adherence to plastic in culture, their expression of non-specific markers and their differentiation potential into cells of mesodermic lineage. Resident in numerous tissues, mesenchymal stromal cells are now available from several sources, including both adult and foetal tissues. After their administration, mesenchymal stromal cells preferentially migrate to injured tissues. Mesenchymal stromal cells have therapeutic effects in numerous animal models of tissue injury by a mechanism not yet clearly understood. Mechanisms likely involved in repair can be the production of paracrine, anti-inflammatory and anti-apoptotic factors, as well as cell replacement by their differentiation potential. Mesenchymal stromal cells possess immunosuppressive properties on both innate and adaptative immunity in vitro and in animal models of autoimmunity. Currently their immunosuppressive properties allow testing of mesenchymal stromal cells in allogenic context, although this use requires further investigations. Mesenchymal stromal cells can be isolated and expanded in vitro in clinical grade conditions. They represent a promising candidate for the cellular therapy of diseases, such as acute myocardial infarction, diabetes, graft versus host disease or neurodegenerative diseases. Critical points including the standardization of production and long term toxicity have to be resolved before their large scale use in clinical conditions.

Anti-T haemolysins: the effects of sialic acid removal and 2-aminoethylisothiouronium bromide treatment of erythrocytes on immune lysis.

BACKGROUND AND OBJECTIVES: Intravascular haemolytic reactions are reported in red-cell T-activated patients after blood transfusion. The relationship between T antigen antibodies present in normal plasma and these reactions remains unclear. In this study, we assessed the haemolytic activity of T antibodies in vitro in comparison with anti-A/B antibodies. MATERIALS AND METHODS: We established a haemolysis assay based on treating target red-blood-cells (RBCs) with 2-aminoethylisothiouronium bromide (AET). Two hundred and seven blood donor sera were analysed for anti-T, anti-A/B haemolysins and anti-T agglutinins. RESULTS: Anti-T haemolysins were found in 4 (1·9%) blood donor sera using a standard haemolysis method and in 174 (84%) samples using AET-treated RBCs. Haemolysis correlated with agglutination titres (P<10(-7) ). With both methods, anti-T haemolysins were much weaker than anti-A and anti-B haemolysins. Gradual desialylation of RBCs showed a correlation between sialic acid level as indicated by agglutination with Sambucus nigra lectin and anti-T mediated haemolysis that was significantly increased (fold 2·4) independently of T antigen expression. CONCLUSION: These data indicate that, in vitro, anti-T-mediated haemolysis depends primarily on the degree of desialylation of target RBCs. They suggest that the haemolytic activity of T antibodies-containing human sera is usually weak and may only become significant in the very rare setting of a profound desialylation of RBCs.

Gene frequencies of the HPA-1 to -6 and -15 human platelet antigens in Tunisian blood donors.

Gene frequencies of mainly human platelet antigens (HPA) -1 to -6 and -15 were determined in 116 Tunisian blood donors. The distribution of HPA-1, -3 and -5 systems approach those found in other Maghrebian populations. Tunisians have the highest frequency of HPA-1b and -5b alleles. The distribution of HPA-1a allele and HPA-4, -6 and -15 systems is similar to Caucasians. Phylogenetic study using the neighbor-joining method and principal component multivariate analysis demonstrate that Tunisians are more closely related to western than to eastern Mediterraneans. This immunogenetic study highlights the relatedness between Mediterranean populations and will serve as a baseline study for future clinical research involving platelet disorders among Tunisians.

Platelet-specific alloantigens and antibodies in Tunisian women after three or more pregnancies.

Pregnancy may allow alloimmunization against human platelet antigens (HPA), which can lead to neonatal alloimmune thrombocytopenia (NAIT). The specificities of alloantibodies are closely related to the distribution of the HPA systems. A total of 281 Tunisian multiparous women (mean number of pregnancies: 4.5) were phenotyped for the HPA-1, -3 and -5 systems, by monoclonal antibody immobilization of platelet antigens (MAIPA). We searched for antibodies against HPA-1a, HPA-3a, HPA-5b and HPA-5a in HPA-1b1b, HPA-3b3b, HPA-5a5a and HPA-5b5b individuals, respectively. The gene frequencies were: 0.83 for HPA-1a, 0.17 for HPA-1b, 0.78 for HPA-3a, 0.22 for HPA-3b, 0.82 for HPA-5a and 0.18 for HPA-5b. Anti-HPA-5b antibodies were present in eight sera and anti-HPA-3a antibodies were present in one serum. The anti-HPA-5b system is the most frequently involved in platelet alloimmunization in Tunisian multiparous women. However, prospective trials are required to confirm this result and to determine the exact frequencies and clinical relevance of platelet alloantibodies in pregnant Tunisian women.

[Transfusion of platelet concentrates]. / Transfusion de concentrés plaquettaires.

Although a number of research have been realized in the aim to rationalize the use of platelet concentrates, these blood products remain absolutely necessary for patients with therapeutic aplasia and for some surgical patients. We will discuss in this work: the main rules of platelet transfusion procedures, threshold values for platelet transfusion, platelet doses, place of curative and prophylactic strategies, refractoriness to platelet transfusion, HLA immunization.

Recommendations of the ISBT Working Party on Granulocyte Immunobiology for leucocyte antibody screening in the investigation and prevention of antibody-mediated transfusion-related acute lung injury.

BACKGROUND: Transfusion-related acute lung injury (TRALI) is currently one of the most common causes of transfusion-related major morbidity and death. Among the many TRALI mediators, leucocyte antibodies have been identified as important triggers of severe TRALI. STUDY DESIGN AND METHODS: These recommendations were compiled by experts of the ISBT Working Party on Granulocyte Immunobiology, based on the results obtained in eight international granulocyte immunology workshops, their personal experiences and on published study results. RESULTS: Leucocyte antibody screening has to include the detection of human leucocyte antigen (HLA) class I, class II and human neutrophil alloantigen antibodies using established and validated techniques. HLA class I antibody detection should be restricted to antibodies clinically relevant for TRALI. To avoid unnecessary workload, TRALI diagnosis should be assessed by consultation with the reporting clinician and thorough exclusion of transfusion-associated circulatory overload/cardiac insufficiency. In patients diagnosed with TRALI having donors with detectable leucocyte antibodies, evidence of leucocyte incompatibility should be provided by either cross-matching or typing of patient for cognate antigen. CONCLUSION: Leucocyte antibody screening for the immunological clarification of TRALI cases as well as for identification of potentially alloimmunized blood donors is feasible and can be performed in a reasonable and quality assured manner. This practice can contribute to the prevention of antibody-mediated TRALI.

[Study of 206 transfused sickle cell disease patients: immunization, transfusion safety and red blood cell supply]. / Etude d'une cohorte de 206 patients drépanocytaires adultes transfusés: immunisation, risque transfusionnel et ressources en concentrés globulaires.

BACKGROUND: Prevention of hemolytic transfusion reactions depends upon our capacity to prevent allo-immunization and conflicts between antigens of transfused red blood cells and antibodies produced by the recipient. In this study, we show that to secure transfusion of sickle cell disease patients, it is necessary to take into account their immunohematologic characteristics in the organization of transfusion. METHODS AND RESULTS: Immunohematological data of 206 chronically transfused patients have been collected as well as phenotypes of transfused units. In order to prevent allo-immunization against C and E antigens for patients typed D+C-E-c+e+ (56%), 26% of the transfused units were D-C-E-c+e+. We found that 47% of the patients had a history of allo-immunization, whereas only 15% produced an antibody the day of inclusion in the study. The non-detectable antibodies were frequently known as dangerous for transfusion. Finally, this study shows the frequency of anti-D in D+ patients and anti-C in C+ patients, pointing out the question of partial antigens. CONCLUSION: To insure optimal transfusion safety for sickle cell disease patients, three points have to be improved: blood donation within the Afro-Caribbean community living in France, access to history of immuno-hematological data, detection of variant antigens, especially within the RH blood system.

[Supplying surgery blocs in red cell concentrates: a collective approach to improve practices]. / Approvisionnement des blocs opératoires en concentrés érythrocytaires: une démarche collective d'amélioration des pratiques.

The need to adapt red blood cells concentrates management in surgery blocs and resuscitation to the changes of the legal framework has lead to a collective approach to improve practices. Gathered by the regional hemovigilance coordinators of the Drass Ile-de-France (regional office of health and social actions), representatives of doctors' ordering transfusions and hemovigilance correspondents of the Assistance publique-Hôpitaux de Paris and representatives of the EFS (French blood establishment) Ile-de-France, together with representatives of the Afssaps (French health products safety agency), have coordinated an assessment of local transfusion practices in surgery blocs and resuscitation that have to be compliant. Each hospital then offered local improvement actions, approved by regional and national instances. We present this original and collective approach of assessing practices leading to offers that both respond to a legal framework and improve blood products flows without damaging transfusion security.

[Xg gene frequencies in Tunisia]. / Fréquence génique du système Xg dans la population tunisienne.

We report a new case of anti-Xg(a) antibody found in a man who, after receiving six units of standard red blood cells, developed a minor nonhemolytic transfusion reaction (chills-hyperthermia). The patient sera was used for an immunophenotyping scale in 777 healthy Tunisian blood donors (678 men; 99 women). The phenotype frequencies of Xg(a+) and Xg(a-) were 67.4% and 32.6% in men and 89 and 11% in women, respectively. The gene frequencies of Xg(a) and Xg were 0.67 and 0.33, respectively. These frequencies are similar to that reported in predominantly white populations.

Rituximab for prevention of delayed hemolytic transfusion reaction in sickle cell disease.

Delayed hemolytic transfusion reaction (DHTR), a life-threatening transfusion complication in sickle cell disease (SCD), is characterized by a marked hemoglobin drop with destruction of both transfused and autologous red blood cells (RBCs) and exacerbation of SCD symptoms. One mechanism of RBCs destruction is auto-antibody production secondary to transfusion. As rituximab specifically targets circulating B cells, we thought that it could be beneficial in preventing this immune-mediated transfusion complication. We report the case of a SCD patient who previously experienced DHTR with auto-antibodies and who needed a new transfusion. DHTR recurrence was successfully prevented by rituximab administration prior transfusion, supporting the safe use of rituximab to prevent DHTR in SCD patients as a second line approach when other measures failed.

Intravenous immunoglobulin and autoimmune thrombocytopenic purpura: 22 years on.

Autoimmune thrombocytopenic purpura is now commonly treated with high doses of intravenous immunoglobulins. Twenty-two years after this treatment was first shown to be effective, several questions remain. We review here current knowledge concerning the frequency and type of side-effects and the probable mechanism of action of intravenous immunoglobulins. We suggest that the currently recommended dose of intravenous immunoglobulins (2 g/kg body weight) could be halved, that the total dose of intravenous immunoglobulins should be administered as a single infusion, that non-responders could be given another equal dose on day 3, and that intravenous immunoglobulins plus prednisolone should be considered as the gold standard for treatment of the most severe forms of the disease. Finally, as intravenous immunoglobulins have only a transient effect, they cannot be considered as a curative treatment for patients with chronic autoimmune thrombocytopenic purpura.

[Are the indications and choice of labile blood products adapted? National survey on prescriber's knowledge]. / Les indications et le choix des produits sanguins labiles sont-ils adaptés? Enquête nationale sur les connaissances des prescripteurs.

OBJECTIVE: There is little data available on current practice related to prescription of labile blood products (LBP) by French physicians. The aim of this study was to assess whether prescriptions were conform to Anaes (French Medicine's agency) guidelines, with regard not only to indications but also quality of the products, so as to define the improvements that could be made. METHOD: Thirty-four clinical case reports, classified by specialties were sent to prescribing physicians working in the regional health centers, from 17 different blood banks, from October 1997 to February 1998. The prescribers were requested to answer only the questions that were specific to their particular field of experience. Each case description included multiple choice questions on the indication for transfusion of concentrated of red blood cells (RBC) and/or platelets (CP) and/or plasma, and the possible requirements for specification or modification of the guidelines applicable to these products. The primary end point of analysis was the adequation of the answers to the Anaes recommendations. RESULTS: Answers were obtained regarding 5092 clinical cases from 818 physicians. The participation rate was of 30%. The specialties were as follows: 34% anesthesiologists, 14% oncologists-haematologists, 13% internal medicine specialists, 11% emergency physicians, 10% paediatricians, 8% obstetricians, 7% geriatricians, and 3% transplantation surgeons. Eighty-two percent of the answers came from physicians working in the public health services. The adequation with the indication for transfusion was of 90.3% for RBC, 92.3% for platelets and 93.8% for plasma. The percentages of correct answers regarding the indications for specification or modification of the LBP were as follows: 90.3% were correct for irradiation (of either RBC or platelets); 68.8% and 53.2% respectively for leukocyte depletion from RBC and platelets; 64% for phenotyped RBC; 68.2% for compatibilized RBC; and 57.3% for apheresis platelet concentrates. There was no difference in results depending on the type of center, private or public, and the quality of LBP prescribed. The answers obtained from the anaesthesiologists' clinical cases were less accurate with regard to RBC but more accurate with regard to PC compared with other specialists. CONCLUSION: This study shows the correct management of the indications for transfusion by the prescribing physicians who participated in the study, but the lack of knowledge with regard to the indications for specifications and/or transformations of LBP. The respect of the indications for transfusion is the corner stone of safe transfusion and this phase should be optimized with improved dissemination of information on transfusion and training for the physicians and programs that would improve the quality.

[HPA-5b neonatal allo-immune thrombocytopenia: two cases described in Tunisia]. / Thrombopénies néonatales dues à un allo-anticorps anti-HPA-5b: à propos de deux cas observés en Tunisie.

UNLABELLED: Alloimmune thrombocytopenia is due to feto-maternal incompatibility in the HPA systems and is usually considered in the diagnosis of neonatal thrombocytopenia after other causes have been excluded. We report on two Tunisian observations of alloimmune neonatal thrombocytopenia due to anti-HPA-5b (Bra) antibodies. CASE REPORT: Two neonates presented at birth with a thrombocytopenic purpura unexplained by usual causes of neonatal thrombocytopenia. Alloimmune neonatal thrombocytopenia was diagnosed by the determination of parental and neonatal platelets antigens phenotypes and by the presence of HPA-5b (antiBra) antibodies in maternal sera. A favourable evolution was obtained after maternal platelet transfusions. CONCLUSION: Alloimmune neonatal thrombocytopenia is a serious affection, which exposes to intracranial haemorrhage. These observations of HPA-5 neonatal alloimmunisation in Tunisia provide additional information on the geographic distribution of the disease and its prognosis.

The nonexpression of CD36 on reticulocytes and mature red blood cells does not modify the clinical course of patients with sickle cell anemia.

It is thought that an increase in the adhesion of circulating reticulocytes to the vascular endothelium may initiate the vascular occlusion underlying the painful crises and organ failures typical of sickle cell disease (SCD). At least 2 receptors, usually present on reticulocytes, seem to be involved in this adhesion process: glycoprotein CD36 (glycoprotein IV) and integrin alpha(4)beta(1) (very late activation antigen--4). Recently, a high frequency of the platelet CD36--deficient phenotype was reported in black Africans. The frequency of this deficiency was similar in subjects with and without SCD. The role of CD36 in vaso-occlusion was then investigated by comparing the clinical course in 2 groups of black Africans homozygous for hemoglobin S, with and without CD36 deficiency, but similar in age, sex, geographical origin, number of alpha-globin genes, and beta-globin gene haplotype. Flow cytometry showed that CD36 was absent from the circulating red blood cells and reticulocytes of platelet CD36--deficient individuals but present on those from patients with normal platelet CD36 expression, and that alpha(4)beta(1) integrin levels were similar on the reticulocytes of the 2 groups. Neither clinical severity, as evaluated by the frequency and characteristics of vaso-occlusive events, nor biological data differed significantly in the 2 groups of patients. Finally, although CD36 has been suggested to play a critical role in the pathogenesis of vaso-occlusion, this study, despite including only a small number of patients, supports the idea that the modulation of expression of a single type of adhesion molecule is insufficient to counteract the pathological process leading to vaso-occlusion in SCD patients. (Blood. 2001;98:966-971)