[Pre-hospital red blood cells transfusions : Logistical aspects]. / Aspects logistiques de la transfusion de concentrés érythrocytaires en milieu préhospitalier.

Pre-hospital red blood cell transfusion is already used in many countries, both in military and civilian settings, and provides a better chance of survival for patients suffering from massive bleeding. However, this is not a current practice in Switzerland. This article aims to study Swiss specificities and provide a turnkey concept for the implementation of red blood cell transfusion in an emergency pre-hospital setting, by road or by air. The transfusion benefits and risks, the logistical aspect and the costs are discussed.

La transfusion de concentrés érythrocytaires (CE) en milieu préhospitalier est déjà réalisée dans de nombreux pays tant dans un contexte militaire que civil et permet d'augmenter les chances de survie des patients souffrant d'hémorragie massive. En Suisse, cette pratique n'est pas courante. Cet article a pour but d'étudier les spécificités suisses et de proposer un concept clé en main pour l'implémentation de la transfusion de CE dans un service de sauvetage médicalisé terrestre ou héliporté. Les bénéfices et les risques de la transfusion, les modalités logistiques et les coûts y sont abordés.

[Autoimmune hemolytic anemia in emergency department]. / Anémie hémolytique autoimmune: quelle prise en charge en urgence ?

Autoimmune hemolytic anemia is an uncommon disease that can be challenging to manage both for the emergency department physician and the general practitioner. The diagnosis is based on specific biological changes and on a positive direct Coombs test. Depending on the severity of the anemia and its clinical impact, an urgent blood transfusion can be required. However, ABO blood group typing and antibody screening may be impaired by autoantibodies. In case of vital need, a transfusion of ABO, Rh D and, if possible, C, c, E, e and Kell antigen matched red cells can be performed, before the complete achievement of the pre-transfusion testing. Further management includes the introduction of immunosuppression and the treatment of a possible underlying disease. Early contact with the hematologist, is strongly recommended.

L'anémie hémolytique autoimmune (AHAI) est une pathologie peu fréquente, dont la prise en charge peut représenter un défi pour l'urgentiste et le généraliste. Le diagnostic est posé sur la base des modifications spécifiques du bilan biologique et sur la positivité du test de Coombs direct. Selon la sévérité de l'anémie, une transfusion sanguine en urgence peut s'avérer nécessaire. Les tests prétransfusionnels peuvent être perturbés par la présence des autoanticorps. En cas d'urgence vitale, on transfusera en compatibilité ABO, Rh D et en essayant de respecter les antigènes C, c, E, e et Kell, sans attendre les tests prétransfusionnels complets. La suite de la prise en charge s'articulera autour de l'introduction de l'immunosuppression ainsi que sur la recherche d'une maladie sous-jacente. L'appel précoce à l'hématologue est de rigueur.

Viral Metagenomics of Blood Donors and Blood-Derived Products Using Next-Generation Sequencing.

Transfusion-transmitted infections remain a permanent threat in medicine. It keeps the burden of the past, marked by serious infections transmitted by transfusion, and is constantly threatened by emerging viruses. The global rise of immunosuppression among patients undergoing frequent transfusions exacerbates this problem. Over the past decade, criteria for donor selection have become increasingly more stringent. Although routine nucleic acid testing (NAT) for virus-specific detection has become more sensitive, these safety measures are only valuable for a limited number of select viruses. The scientific approach to this is however changing, with the goal of trying to identify infectious agents in donor units as early as possible to mitigate the risk of a clinically relevant infection. To this end, and in addition to an epidemiological surveillance of the general population, researchers are adopting new methods to discover emerging infectious agents, while simultaneously screening for an extended number of viruses in donors. Next-generation sequencing (NGS) offers the opportunity to explore the entire viral landscape in blood donors, the so-called metagenomics, to investigate severe transfusion reactions of unknown etiology. In the not too distant future, one could imagine this platform being used for routine testing of donated blood products.

Cell-free nucleic acids are present in blood products and regulate genes of innate immune response.

BACKGROUND: Extracellular nucleic acids circulate in plasma. They are expected to be present in manufactured blood products eligible for transfusion, but little is known about their biological activity on human cells. The aim of this study is to investigate whether cell-free nucleic acids (CFNAs) are present and biologically active in red blood cell units (RBCUs), fresh frozen plasmas, and platelet concentrates. STUDY DESIGN AND METHODS: CFNAs were extracted from RBCUs, fresh frozen plasma, and platelet concentrates. Their nature and structure were analyzed by regular methods of nucleic acid detection/quantification. A normalized polymerase chain reaction combining amplification of a CFNA marker (Alu 115) and amplification of an internal nonhuman DNA control spiked in all samples (phiX 174) was developed to study CFNA release after RBCU storage. The impact of CFNAs on gene regulation was tested by microarray after coculture with peripheral blood mononuclear cells and macrophages. RESULTS: Extracellular double-stranded DNA was present in all blood products, with higher amounts found in cellular suspensions (RBCUs and platelet concentrates). Storage up to 40 days did not influence release from RBCUs, and CFNA amount varied considerably from one unit to another. Microarray experiments showed that exposition of macrophages to CFNA increased the expression of genes involved in the innate immune response including chemokines, chemokine receptors, and receptors of the innate response. CONCLUSION: CFNAs are present in blood products. Immunoregulatory properties of CFNA are shown in vitro, providing new insights on biologically active components of blood products besides those for intended therapeutic use.

Metagenomics analysis of the virome of 300 concentrates from a Swiss platelet bank.

BACKGROUND AND OBJECTIVES: Platelet concentrates are frequently transfused to patients with reduced immunity. An exhaustive description of their viral content is needed to prevent unwanted infection. MATERIAL AND METHODS: To track viral sequences, a shotgun metagenomics approach was used on a bank of 300 platelets concentrates. Sequences were analysed through the diagnostics-oriented pipeline ezVIR. RESULTS: We only observed viruses commonly described in healthy individuals. CONCLUSION: Herein is reported the first viral landscape of a platelet concentrates bank.

Metagenomics analysis of red blood cell and fresh-frozen plasma units.

BACKGROUND: Although the risk of transmitting infectious agents by blood transfusion is dramatically reduced after donor selection, leukoreduction, and laboratory testing, some could still be present in donor's blood. A description of metagenomes in blood products eligible for transfusion represents relevant information to evaluate the risk of pathogen transmission by transfusion. STUDY DESIGN AND METHODS: Detection of viruses, bacteria, and fungi genomes was made by high-throughput sequencing (HTS) of 600 manufactured blood products eligible for transfusion: 300 red blood cell (RBC) and 300 fresh-frozen plasma (FFP) units. RESULTS: Anelloviruses and human pegivirus, frequent in the blood of healthy individuals, were found. Human papillomavirus type 27 and Merkel cell polyomavirus, present on the skin, were also detected. Unexpectedly, astrovirus MLB2 was identified and characterized in a FFP unit. The presence of astrovirus MLB2 was confirmed in donor's blood and corresponded to an asymptomatic acute viremia. Sequences of bacteria and fungi were also detected; they are likely the result of environmental contamination. CONCLUSION: This study demonstrates that HTS is a promising tool for detecting common and less frequent infectious pathogens in blood products.

Physiology of iron metabolism.

A revolution occurred during the last decade in the comprehension of the physiology as well as in the physiopathology of iron metabolism. The purpose of this review is to summarize the recent knowledge that has accumulated, allowing a better comprehension of the mechanisms implicated in iron homeostasis. Iron metabolism is very fine tuned. The free molecule is very toxic; therefore, complex regulatory mechanisms have been developed in mammalian to insure adequate intestinal absorption, transportation, utilization, and elimination. 'Ironomics' certainly will be the future of the understanding of genes as well as of the protein-protein interactions involved in iron metabolism.

Ferritin: A Biomarker Requiring Caution in Clinical Decision.

OBJECTIVES: To determine the ferritin inter-assay differences between three "Conformité Européenne" (CE) marked tests, the impact on reference intervals (RI), and the proportion of individuals with iron deficiency (ID), we used plasma and serum from healthy blood donors (HBD) recruited in three different Switzerland regions. DESIGN AND METHODS: Heparinized plasma and serum from HBD were obtained from three different transfusion centers in Switzerland (Fribourg, Geneva, and Neuchatel). One hundred forty samples were recruited per center and per matrix, with a gender ratio of 50%, for a total of 420 HBD samples available per matrix. On both matrices, ferritin concentrations were quantified by three different laboratories using electrochemiluminescence (ECL), latex immunoturbidimetric assay (LIA), and luminescent oxygen channeling immunoassay (LOCI) assays, respectively. The degree of agreement between matrices and between the three sites/methods was assessed by Passing-Bablok and we evaluated the proportion of individuals deemed to have ID per method. RESULTS: Overall, no difference between serum and heparinized plasma ferritin values was observed according to Passing-Bablok analyses (proportional bias range: 1.0-3.0%; maximum constant bias: 1.84 µg/L). Significant median ferritin differences (p < 0.001 according to Kruskal-Wallis test) were observed between the three methods (i.e., 83.6 µg/L, 103.5 µg/L, and 62.1 µg/L for ECL, LIA, and LOCI in heparinized plasma, respectively), with proportional bias varying significantly between ±16% and ±32% on serum and from ±14% to ±35% on plasma with no sign of gender-related differences. Affecting the lower end of RI, the proportion of ID per method substantially varied between 4.76% (20/420) for ECL, 2.86% (12/420) for LIA, and 9.05% (38/420) for LOCI. CONCLUSIONS: Serum and heparinized plasma are exchangeable for ferritin assessment. However, the order of magnitude of ferritin differences across methods and HBD recruitment sites could lead to diagnostic errors if uniform RI were considered. Challenging the recently proposed use of uniform ferritin thresholds, our results highlight the importance of method- and region-specific RI for ferritin due to insufficient inter-assay harmonization. Failing to do so significantly impacts ID diagnosis.

Kinetics of disappearance and appearance of isoagglutinins A and B after ABO-incompatible hematopoietic stem cell transplantation.

ABO-incompatible allogeneic hematopoietic stem cell transplantation (HSCT) can be complicated by poor red cell engraftment and hemolysis, both mediated by isoagglutinins. Anecdotally, isoagglutinins indicates an activation of donor's immunity or even relapse. Consequently, the routine monitoring of isoagglutinins could help physicians to predict the risk of complications. The purpose of this study is to investigate the time to disappearance and appearance of isoagglutinins after ABO-incompatible allogeneic HSCT. In a one-year follow-up, data of 136 ABO-incompatible hematopoietic stem cell (HSC) allogeneic transplanted patients were studied, of which 60 had major, 61 minor and 15 bidirectional incompatibility. Survival analyses were conducted and association with hematological diseases, HLA-compatibility and transplantation strategy was investigated. We observed a disappearance of isoagglutinin A in 82.0% of cases at one year with a median and 75th percentile of 38.4 and 138.6 days, respectively. For isoagglutinin B, these same values were 96.4%, 15.9 and 29.1 days, respectively. The appearance of isoagglutinin A occurred in 10.7% of cases. Disappearance of isoagglutinin A was significantly slower in patients with myeloid diseases compared to other diseases. The results of this study provide useful values to detect early risks of preventable immunohematological complications and possibly, in exceptional cases, relapse.

Neutralization capacity of antibodies elicited through homologous or heterologous infection or vaccination against SARS-CoV-2 VOCs.

Emerging SARS-CoV-2 variants raise questions about escape from previous immunity. As the population immunity to SARS-CoV-2 has become more complex due to prior infections with different variants, vaccinations or the combination of both, understanding the antigenic relationship between variants is needed. Here, we have assessed neutralizing capacity of 120 blood specimens from convalescent individuals infected with ancestral SARS-CoV-2, Alpha, Beta, Gamma or Delta, double vaccinated individuals and patients after breakthrough infections with Delta or Omicron-BA.1. Neutralization against seven authentic SARS-CoV-2 isolates (B.1, Alpha, Beta, Gamma, Delta, Zeta and Omicron-BA.1) determined by plaque-reduction neutralization assay allowed us to map the antigenic relationship of SARS-CoV-2 variants. Highest neutralization titers were observed against the homologous variant. Antigenic cartography identified Zeta and Omicron-BA.1 as separate antigenic clusters. Substantial immune escape in vaccinated individuals was detected for Omicron-BA.1 but not Zeta. Combined infection/vaccination derived immunity results in less Omicron-BA.1 immune escape. Last, breakthrough infections with Omicron-BA.1 lead to broadly neutralizing sera.

Safety of Red Blood Cell Transfusion Using Small Central Lines in Neonates: An in vitro Non-inferiority Study.

Aim: This study aimed to investigate the safety of transfusing red blood cell concentrates (RBCCs) through small [24 gauge (24G)] and extra-small [28 gauge [28G)] peripherally inserted central catheters (PICCs), according to guidelines of transfusion practice in Switzerland. Methods: We performed a non-inferiority in vitro study to assess the safety of transfusing RBCC for 4 h at a 4 ml/h speed through 24G silicone and 28G polyurethane PICC lines, compared with a peripheral 24G short catheter. The primary endpoint was hemolysis percentage. Secondary endpoints were catheter occlusion, inline pressure, and potassium and lactate values. Results: For the primary outcome, hemolysis values were not statistically different among catheter groups (0.06% variation, p = 0.95) or over time (2.75% variation, p = 0.72). The highest hemolysis values in both 24G and 28G PICCs were below the non-inferiority predefined margin. We did not observe catheter occlusion. Inline pressure varied between catheters but followed the same pattern of rapid increase followed by stabilization. Potassium and lactate measurements were not statistically different among tested catheters (0.139% variation, p = 0.98 for potassium and 0.062%, p = 0.96 for lactates). Conclusions: This study shows that RBCC transfusion performed in vitro through 24G silicone and 28G polyurethane PICC lines is feasible without detectable hemolysis or pressure concerns. Also, it adds that, concerning hemolysis, transfusion of RBCC in small and extra-small PICC lines is non-inferior to peripheral short 24G catheters. Clinical prospective assessment in preterm infants is needed to confirm these data further.