Delayed hemolytic transfusion reaction in the French hemovigilance system.

In France, reporting of adverse events related, or likely to be related, to transfusion is mandatory. Since its creation in 1993, the French hemovigilance system has contributed to a better recognition of unappreciated risks like delayed hemolytic transfusion reactions (DHTR) in sickle-cell disease (SCD) patients. Long under-reported or misclassified, reports of this serious complication of transfusion have improved, particularly through the dissemination of information within the hemovigilance network. To our knowledge, the French hemovigilance system has one of the largest series of DHTR in SCD patients. Guidelines for diagnosis and reporting to hemovigilance system as well as a specific reporting form are being developed, which should contribute to the quality of data essential for epidemiological studies.

[Is the research of posttransfusional alloantibodies still relevant?] / Est-ce que la réalisation de la recherche d'anticorps antiérythrocytaires post­transfusionnelle est toujours pertinente ?

The decision of November 6th, 2006 defining the principles of best practices recommends that posttransfusional red cell alloantibodies research is performed after one to three months after. In the University hospital of Brest, the haemovigilance unit takes charge of sending the medical prescription within the required time and centralizing the results. We wished to estimate if the realization of this research still remains relevant. METHODS: A prospective analysis was performed in 2015. We evaluated the realization rate, the red cell alloantibodies rate and the recipient adverse reactions with the diagnostic category: alloimmunization (delayed serological transfusion reaction, DSTR). RESULTS: In 2015, 2162 prescriptions were sent to the 3271 transfused patients. One thousand and eighteen red cell alloantibodies research were done, i.e. a return rate of 61%. Among them, 12 alloantibodies appeared (0.9%) within an average of 56 days. Thirty-three other alloantibodies appeared and were discovered most frequently before a new transfusion. In 10 cases, a posttransfusional research was done that was negative. A survey was conducted among GHCOH members to describe the practices in these health institutions. Twelve questionnaires were analysed. Ten institutions performed a posttransfusional alloantibodies research by issuing a prescription at the patient's exit with a return rate between 0.14 and 16%; 1 institution has a centralized organization with a return rate of 68.3%; 1566 red cell alloantibodies research were performed and among them, 24 alloantibodies appeared (1.53%). CONCLUSION: These results indicate that to be effective, the management of this biological test must be centralized. Despite this, the red cell alloantibodies rate remains very low (0.9 and 1.53%) and raises the question of the relevance of this systematic testing after transfusion, which is in any case mandatory before a new transfusion of red blood cells.

[Delayed hemolytic transfusion reaction in sicle cell disease patients: a new challenge for the Hemovigilance network]. / Les hémolyses retardées post-transfusionnelles chez les patients drépanocytaires : un nouveau défi pour le réseau d'hémovigilance.

Delayed hemolytic reaction transfusion in patients with sickle cell disease (SCD) is a serious and still under diagnosed event. Clinical and biological presentation mimics an acute SCD complication. It is a life-threatening event, especially in hyperhemolysis syndrome (HS) characterized by a massive destruction of both the donor's and patient's red blood cells. The main cause is related to the presence of alloantibodies directed against red blood cell antigens, more rarely autoantibodies. In approximately a third of the cases, no new antibody is highlighted. Pathophysiological hypotheses are still under debate but most of the authors agree on the role played by the SCD inflammatory state. Several therapeutic approaches are used but the data are still insufficient to estimate their efficiency. It is admitted that a new transfusion may exacerbate the phenomenon and the benefit-risk of any transfusion must be carefully evaluated. Measures limiting alloimmunization and rigorous follow-up of SCD patients and their immunohematologic status can prevent some of these accidents. The Hemovigilance network has a role to play in the recognition and the description of this risk. A first analysis realized on the French national Hemovigilance database of the French National Agency for Medicines and Health Products Safety (ANSM) over the period 2000-2013, shows us interesting information but some inadequacies, described here, must be taken into account to strengthen these data and insure in the future a better reporting quality.

Thrombin triggers the de novo expression of an inducible NO synthase in porcine aortic valve endothelial cells.

The nitric oxide (NO) production by porcine aortic valve endothelial cells was estimated in cusps incubated at 37 degrees C by measuring their cyclic GMP content and the nitrite levels of the incubation medium. After a stabilization period, incubation for 5 min with acetylcholine, bradykinin, ADP and bovine thrombin resulted in a receptor-mediated increase in cyclic GMP which could be blocked by EGTA, N-omega-nitro-L-arginine methyl ester (L-NAME) and NG-monomethyl-L-arginine (L-NMMA). Incubation with lipopolysaccharide (endotoxin) from E. coli O111:B4 or bovine for 5 h, dose-dependently increased nitrite production as well as cyclic GMP content. The elevated nitrite production was completely abolished in the presence of the protein synthesis inhibitor cycloheximide, was reduced by more than 50% by dexamethasone but was not affected by EGTA. L-NMMA dose-dependently reduced the increased nitrite production and cyclic GMP content. These results suggest that besides the presence of a constitutive NO synthase in porcine aortic valve endothelial cells thrombin, like lipopolysaccharide, triggers the de novo expression of an inducible Ca(2+)-independent NO synthase.