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.

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.

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.

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.

[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.

[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.

[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.

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.

Pregnancy in women with immune thrombocytopenic purpura.

Thirty-six women with immune thrombocytopenic purpura were studied during 37 pregnancies, and maternal characteristics with predictive value for the fetal platelet count were determined. Nine neonates were thrombocytopenic, with a platelet count of less than 50 x 10(9)/L in eight. Four of these nine neonates delivered to a subgroup of 31 mothers were studied prospectively; the frequency of thrombocytopenia in neonates of women with immune thrombocytopenic purpura was thus 13%. Only two of these nine neonates presented with hemorrhagic syndromes (two, petechial purpura; one, intracranial bleeding). The frequency of neonatal thrombocytopenia was higher in mothers with deep thrombocytopenia and in those who had not responded to corticosteroid treatment following diagnosis. No prognostic value could be assigned to the other maternal characteristics studied, such as a history of splenectomy, maternal treatment at the time of delivery, or the presence of platelet autoantibodies evaluated either with the platelet immunofluorescence test or the platelet Western blot immunoassay.

Hepatitis B vaccination in diabetic patients. Randomized trial comparing recombinant vaccines containing and not containing pre-S2 antigen.

OBJECTIVE: To investigate the immunogenicity of two recombinant hepatitis B vaccines containing S antigen alone (Engerix B) or both S and pre-S2 antigens (GenHevac B) in diabetic patients. RESEARCH DESIGN AND METHODS: Of the adult diabetic patients, 71 (26 IDDM, 45 NIDDM) were randomized to receive Engerix B or GenHevac B at 0, 1, 2, and 12 months in a single-blind clinical trial; if the antibody to hepatitis B surface antigen (anti-HBs) titers were < 10 i.u./l at month 4, a fourth injection of vaccine was given. A positive response was defined by anti-HBs titer > or = 10 IU/l at month 13. RESULTS: The anti-HBs response rate and the titers of anti-HBs did not differ significantly between the two types of vaccine. Overall, > 90% of the patients responded at month 13. In patients vaccinated with GenHevac B, anti-pre-S2 antibodies appeared earlier than anti-HBs. The anti-HBs response tended to decrease with age (P = 0.07) and tended to be higher in IDDM patients than in NIDDM patients (P = 0.06). Metabolic control, as assessed by HbA1c level, did not influence the response rate. The presence of the HLA DQ2 allele was associated with a low response. CONCLUSIONS: A large majority of diabetic patients can be efficiently vaccinated against the hepatitis B virus using a booster dose at month 4. The choice of the vaccine (with or without pre-S2 antigen) appears to have little influence, if any, on the response rate.

Predictive value of host-specific donor helper T-cell precursor frequency for acute graft-versus-host disease and relapse in HLA-identical siblings receiving allogeneic bone marrow transplantation for hematological malignancies.

BACKGROUND: Acute graft-versus-host disease (aGVHD) is still one of the main causes of morbidity and mortality after allogeneic bone marrow transplantation. Attempts to avoid GVHD are associated with an increased risk of relapse, probably because the graft-versus-leukemia effect is also abrogated. It was recently suggested that a high frequency of host-specific donor helper T cell precursors (HTLp) might be predictive of significant aGVHD (grade > or = II). METHODS: We retrospectively studied the frequency of HTLp by means of simplified limiting-dilution analysis to determine its predictive value for aGVHD and relapse. Pre-bone marrow transplantation, host-specific donor HLTp frequencies were analyzed in 32 patients who had received marrow from HLA-identical siblings for hematological malignancies, in terms of aGVHD and relapse. RESULTS: HTLp frequencies were significantly higher in patients who had aGVHD > or = grade II (n=14) than in those without aGVHD (n=18) (P=0.007). Patients who relapsed (n=13) had significantly lower HTLp frequencies than those who did not relapse (n=19) (P<0.0001). The probabilities of relapse (Kaplan-Meier method) when the HTLp frequency was higher and lower than 1/200,000 were 0% and 88%, respectively (P<0.0001). CONCLUSIONS: The definition of HTLp cut-off values predictive of aGVHD and relapse should contribute to donor selection and could open the way to protocols adapting immunomodulation to the likely risk of aGVHD and relapse.

Screening for autoimmune markers is unnecessary during follow-up of adults with autoimmune thrombocytopenic purpura and no autoimmune markers at onset.

In an attempt to evaluate the frequency of autoimmune markers in autoimmune thrombocytopenic purpura (AITP) and to determine if autoimmune markers in patients with isolated AITP were associated with particular disease manifestations, we analyzed records of 122 consecutive adults with AITP. Twenty-nine patients (24%) had significant titers of one or several autoimmune markers at AITP onset. Among them, 16 (13%) had antinuclear antibodies. The presence of autoimmune markers did not correlate with presenting feature, response to treatment or long-term outcome of AITP. Six patients (5%) developed seven autoimmune diseases during follow-up, comprising systemic lupus erythematosus, an antiphospholipid syndrome, autoimmune haemolytic anemia (n = 2), Grave's disease, Hashimoto's disease and primary biliary cirrhosis. At AITP onset, three of these patients had isolated biological markers of the autoimmune disease they later developed. The annual average incidence rate of autoimmune diseases was 1% per patient-year in the entire group and 0.4% in the group of patients with no autoimmune markers at AITP onset. This low rate is probably due to careful assessment at diagnosis for concomitant overt autoimmune disease. We recommend extensive screening for autoimmune markers at AITP onset, and careful follow-up of patients with autoimmune markers. Routine screening for autoimmune markers during AITP follow-up is not necessary for patients with no autoimmune markers at AITP onset. Systemic lupus erythematosus (SLE) and other autoimmune disorders can complicate autoimmune thrombocytopenic purpura (AITP) or be diagnosed concomitantly with otherwise unremarkable AITP (1, 2). However, the frequency and prognostic value of isolated autoimmune markers (i.e. not associated with an autoimmune disorder), particularly antinuclear antibodies (ANA) at AITP onset or during follow-up is controversial (3-8). For example, the committee organized by George et al. (9) to write guideline on the diagnosis and treatment of AITP stated that the search for ANA and lupus anticoagulant were of "uncertain appropriateness at diagnosis and during follow-up". In an attempt to help practicians to make decisions, we analyzed the frequency of autoimmune markers and autoimmune disorders at onset and during the follow-up in 122 adults with AITP and no overt autoimmune disease at diagnosis. These consecutive patients were followed by the same physician for a mean period of 6 years, and had routine screening tests for autoimmune markers and disorders at onset, before steroid therapy, and regularly during follow-up.

High resolution HLA class I and II typing and CTLp frequency in unrelated donor transplantation: a single-institution retrospective study of 69 BMTs.

UNLABELLED: The results of unrelated donor transplantation (URD-BMT) are difficult to analyze since the continuous advances in HLA typing technology allow the detection of new mismatches unknown at the time of transplantation. We sought to confirm that matched recipient-donor pairs are in fact often mismatched when advanced HLA typing techniques are used. We retrospectively studied the impact of the results of high resolution HLA typing for HLA class I (-A, -B, -C) and HLA class II (-DR, -DQ, -DP) loci, and cytotoxic T lymphocyte precursor (CTLp) frequency, on the outcome of 69 URD-BMT procedures. At the time of transplant, six (6/69) and two (2/69) donor-recipient pairs were mismatched for HLA class I (-A and -B by serology) and HLA class II, respectively, while one pair was mismatched for both HLA class I and II. Using high resolution DNA typing, HLA class I mismatches were found in 31 (45%) pairs and HLA class II mismatches in nine (13%) pairs. Twenty-three of the 69 pairs were HLA-C mismatched. Low CTLp frequencies were found among the 19 HLA class I matched pairs tested, and also in 5/14 mismatched pairs (of whom three had severe aGVHD). The overall survival of the cohort was 28 +/- 6%. Among the 33 patients who were fully matched with their donors, the survival rate was 66% in the 18 patients with a standard hematological risk and 9% in the 15 high risk patients. Only two of the 33 patients developed severe aGVHD, and only one had graft rejection. Among the 36 mismatched pairs, the survival rate was 31% in the 13 patients with a standard hematological risk and 8% in the 23 high risk patients. Sixteen of these 36 patients died from severe aGVHD and four had graft failure or rejection. Three of the 10 patients with only an HLA-C mismatch died from severe aGVHD, and two had graft rejection. IN CONCLUSION: (1) donor-recipient matching based on high resolution HLA class I and II DNA typing is associated with significantly better outcome after URD-BMT; (2) the results of URD-BMT with classical GVHD prevention are comparable to those of geno-identical BMT when donor and recipient are fully matched for HLA-A, -B, -C, -DRB1 and -DQB1 on the basis of high resolution typing; (3) CTLp frequencies do not correlate constantly with HLA class I matching, and our results fail to show that CTLp assay can distinguish between permissible and non-permissible class I mismatches; (4) clinical trials involving donor-recipient pairs with known HLA class I mismatches are needed to improve aGVHD prevention without increasing graft failure rate.

A UMLS-based knowledge acquisition tool for rule-based clinical decision support system development.

Decision support systems in the medical field have to be easily modified by medical experts themselves. The authors have designed a knowledge acquisition tool to facilitate the creation and maintenance of a knowledge base by the domain expert and its sharing and reuse by other institutions. The Unified Medical Language System (UMLS) contains the domain entities and constitutes the relations repository from which the expert builds, through a specific browser, the explicit domain ontology. The expert is then guided in creating the knowledge base according to the pre-established domain ontology and condition-action rule templates that are well adapted to several clinical decision-making processes. Corresponding medical logic modules are eventually generated. The application of this knowledge acquisition tool to the construction of a decision support system in blood transfusion demonstrates the value of such a pragmatic methodology for the design of rule-based clinical systems that rely on the highly progressive knowledge embedded in hospital information systems.

[Not Available].

Autoimmune thrombocytopenic purpura (AITP) is a common nonmalignant disease that can be complicated by life-threatening haemorrhage. The thrombocytopenia is due to antiplatelet antibodies that opsonise the platelet membrane, leading to platelet destruction by phagocytes, principally in the spleen. Acute and chronic forms are observed; spontaneous remission only occurs in the former. Treatment with high doses (2 g/kg) of intravenous immunoglobulin (IVIg) originating from the plasma of blood donors is frequently given at disease onset in severe thrombocytopenia, as it regularly induces rapid platelet recovery. The best responses are obtained when IVIg is administered over 2 days and when ;intact' (chemically unmodified) immunoglobulin concentrates are used. However, the effect is usually transient, severe adverse effects may occur and the cost is high, leading many physicians to reduce the dosage of IVIg and to limit its use to patients with life-threatening complications and contraindications to corticosteroids. Finally, even if repeated administration of IVIg can sometimes induce prolonged remissions, there is no proof that the treatment can cure a significant number of patients with chronic AITP. Anti-D (Rhesus) human immunoglobulin concentrates can also transiently increase the platelet count in patients with AITP. However, the platelet response is slower than with IVIg and use should be limited to selected patients in whom a transient, possibly delayed, increase in the platelet count is required, or where splenectomy is contraindicated.

Plateletpheresis concentrates produced with the COMTEC cell separator: the French experience.

The latest generation of cell separators such as Trima (Gambro), Amicus (Baxter) and AS-TEC 204 (Fresenius), allow the collection of leucocyte-reduced platelet concentrates without secondary filtration. Fresenius has recently developed the COMTEC cell separator whose performance has been evaluated by several teams in France. This new cell separator is an improved version of the Fresenius AS-TEC 204 cell separator, designed to allow more efficient platelet collections. This study reports on the experience of six French teams (from Bordeaux, Clermont-Ferrand, Creteil, Dijon, Lille and Nancy) who obtained 696 leucocyte-reduced plateletpheresis concentrates in the course of collection using the new Fresenius COMTEC cell separator. All healthy volunteer donors fulfilled French selection criteria for platelet apheresis. Donors were eligible if they had suitable venous accesses, if their bodyweight was *50 kg and if their pre-apheresis platelet count was >150 x 10(9) l(-1). Between 4606 and 5229 ml of blood were processed. The mean volume of the platelet concentrates was between 439 and 493 ml (mean 460 +/- 63 ml). The platelet yield was of the order of 5.18 +/- 1.02 x 10(11) with only one platelet concentrate below the norm of 2 x 10(11) platelets (0.91 x 10(11)). No plausible explanation for this was found. The residual leucocyte levels conform to current norms. The platelet concentrates contained less than 1 x 10(6) leucocytes per concentrate (mean 0.233 +/- 0.150 x 10(6) leucocytes) in more than 97% of the components produced with >95% statistical confidence. The efficacy of the cell separator (52.44 +/- 7.35%) is comparable to that of other separators. The Fresenius COMTEC cell separator makes it possible to obtain leucocyte-reduced platelet concentrates which comply with current standards both in terms of platelet content and residual leucocyte level.