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Le test de Coombs direct est utilise en premiere ligne pour le diagnostic de l'anemie hemolytique auto-immune (AHAI). Il permet de detecter la presence d'anticorps ou de fragments du complement a la surface d'erythrocytes. La positivite du test peut atteindre 0,1 % dans une population de donneurs de sang et jusqu'a 15 % chez des personnes malades hospitalisees. Vu le nombre important de publications associant la COVID-19 et l'AHAI, le taux de positivite du test de Coombs direct a ete evaluee aux Cliniques Universitaires Saint-Luc (Bruxelles). Une large cohorte de patient hospitalises dans notre hopital (n = 225) a ete selectionnee sur base d'une PCR recemment positive pour le SARS-CoV-2. 44 % des echantillons recoltes ont donne un resultat positif. Une difference statistiquement significative a pu etre mise en evidence entre le taux de positivite des patients hospitalises dans une unite de soins classique et celui des patients aux soins intensifs. Ceci plaide en faveur du fait qu'un test de Coombs positif pourrait former un critere de gravite de la maladie. Le plasma de patients SARS-CoV-2-positifs ayant un Coombs direct a ete incube avec des globules rouges de patients COVID-19 ne presentant pas de test de Coombs direct positif. Une agglutination systematique est observee lorsque ces globules sont testes pour un Coombs direct. Le plasma des patients COVID a aussi ete incube avec des globules de poches sanguines, generant egalement une agglutination. Avec le plasma de patients non-COVID, ces derniers globules n'agglutinaient pas. Le Coombs direct semble donc « transmis » d'un globule rouge a l'autre par l'intermediaire du plasma des patients COVID ayant un Coombs direct positif. (French) [ABSTRACT FROM AUTHOR] Copyright of Transfusion Clinique et Biologique is the property of Elsevier B.V. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Objectives Our study aimed to update the seroprevalence and factors associated with anti-dengue virus (DENV) antibody positivity among blood donors and to discuss their implications for blood supply. Background Questions on the potential transmission of DENV by transfusion increased after the documentation of the risk of transmission of the West Nile virus. This risk was estimated after transfusion of DENV RNA-positive blood units of up to 37.5%. In Burkina Faso, very few studies on DENV in blood donors have been conducted. As a result, there were no reliable data on DENV to allow the implementation of appropriate measures to control the risk of transmission of the dengue virus by blood transfusion. Methods We conducted a 4-week cross-sectional study from December 4 to 30, 2016. Blood donors of both genders, aged 18-60 years, accepted for blood donation after medical selection were consecutively enrolled. Results Our study included a total of 1007 blood donors, in which donors living in urban areas represented 78.2%. The mean age was 26.1 ± 8.1 years. After adjustment in a multiple regression logistic model, the odds of having IgG anti-DENV increased as age increased. The odds of DENV was 53% lower in rural areas (OR = 0.47; P = .000) compared to urban settings and 42% lower in mobile sites (OR = 0.58; P = .03) compared to fixed ones. Conclusion Our study provides new and useful insights for future research on the risk of TT-DENV throughout blood transfusion.

Traceability is an essential tool for haemovigilance and transfusion safety. In Burkina Faso, the implementation of haemovigilance has been achieved as part of a pilot project from 2005 to 2009. Our study aims to evaluate the traceability of blood transfusions and reporting of adverse reactions over the 6-year postpilot phase. A cross-sectional study including all blood units ordered between 2010 and 2015 has been conducted in public and private health care facilities supplied with blood products by the transfusion center of Bobo-Dioulasso. The complete traceability was possible for 83.5% of blood units delivered. Adverse reactions were reported in 107 cases representing 2.1/1,000 blood units per annum. Transfusions of wrong blood to wrong patient were reported in 13 cases. Our study shows that the haemovigilance system in Burkina Faso must be improved. Healthcare workers have to be sensitized on how traceability and haemovigilance could impact the quality of care provided to patients.

International audience

Human leukocyte antigen (HLA) class I antigen defects may have a negative impact on the growing application of T-cell–based immunotherapeutic strategies for treatment of leukemia. Therefore in the present study, taking advantage of a large panel of HLA class I allele–specific human monoclonal antibodies, we have compared HLA class I antigen expression on leukemic cells with that on autologous and allogeneic normal cells. Down-regulation of HLA-A and/or -B allospecificities was present in the majority of the patients studied. However, down-regulation did not affect all HLA class I alleles uniformly, but was almost exclusively restricted to HLA-A allospecificities and to HLA-B allospecificities which belong to the HLA-Bw6 group. The latter allospecificities, at variance from those that belong to the HLA-Bw4 group, do not modulate the interactions of leukemic cells with natural killer (NK) cells. Therefore, our results suggest that the selective down-regulation of HLA-A and HLA-Bw6 allospecificities associated with HLA-Bw4 preservation provides leukemic cells with an escape mechanism not only from cytotoxic T lymphocytes (CTLs), but also from NK cells. As a result T-cell–based immunotherapeutic strategies for leukemia should utilize HLA-Bw4 alloantigens as restricting elements since a selective HLA-Bw4 allele loss would provide leukemic cells with an escape mechanism from CTLs, but would increase their susceptibility to NK cell–mediated lysis. (Blood. 2004;103:3122-3130)

This paper summarises the guidelines and recommendations that were generated during a number of discussion forums attended by the majority of Belgian cytometry laboratory professionals. These forums focused on the rational and optimal use of flow cytometric evaluations in the clinical laboratory setting. The aim was to improve the coherence of the testing panels and the quality of the results and -as such-the clinical diagnostic information. It was also the aim to provide the Belgian prescribing physician and interested laymen with an updated overview of the flow cytometric possibilities. Emphasis is placed on immunophenotyping of haematological malignancies, hematopoietic progenitor cell counting and follow-up of the viral infection caused by the human immunodeficiency virus.

We report here the distributions of lymphocyte populations bearing the following antigens: CD3 (T cells), CD19 (B cells), CD4 (T helper/inducer cells), CD8 (T suppressor/cytotoxic and some NK cells), and CD3-, CD16+, and/or CD56+ (NK cells). At four sites, analyses were performed on healthy, normal subjects between the ages of 18 and 70, using identical flow cytometry systems and techniques. Reference ranges (unadjusted for sex differences and age variation) are CD3 (61 to 85%), CD19 (7 to 23%), NK (6 to 29%), CD4 (28 to 58%), and CD8 (19 to 48%). The lymphocyte subpopulation distributions for all antigens were found to be similar at all sites. By combining data from all sites, it has been possible to estimate age variation and sex differences for each of these subpopulations. Age and sex associated differences are substantial for some lymphocyte subsets (CD3, CD4, NK cells), and proper accounting of these effects is essential in evaluating the individual patient, if further disease-related variation is to be accurately and consistently assessed. It appears possible to recommend reference ranges for lymphocyte population parameters applicable across national and laboratory boundaries. These ranges provide a basis for comparing results from different institutions and for combining such results on subjects and patients from several institutions, provided the methodology and equipment are identical at all sites.