Immunisation anti-érythrocytaire et anti-HLA au cours des hémoglobinopathies

AimEvaluate the anti-erythrocyte and anti-HLA immunization rates in hemoglobinopathies.Patients and methodsCross-sectional study (October 2009–March 2010) on 83 patients followed for hemoglobinopathies. The irregular antibodies research is realized by two techniques: indirect Coombs and enzymatic technique on gel cards. The search for anti-HLA class I antibodies is done by complement dependent lymphocytotoxicity.ResultsThe mean age was 30 years (14–64 years), the sex ratio M/F is 0.84. Our series included 42 cases of sickle cell disease (29 homozygous sickle cell anemia and 13 sickle-thalassemia) and 41 cases of thalassemia syndromes (26 major and 15 intermediate). The anti-erythrocyte alloimmunization rate is 10.84% without difference between thalassemia syndromes and sickle cell disease. The autoimmunization rate (22.89%) is higher in thalassemia syndromes (41.46%) than in the sickle cell disease (7.14%) (P < 0.001). The anti-HLA immunization rate is 31.6% without difference between thalassemia syndromes and sickle cell disease. The young age, transfusion at a young age and the total number of transfusions are the factors that increase the risk of anti-erythrocyte autoimmunization. No clinicobiological parameter does influence the anti-erythrocyte and anti-HLA alloimmunization. There is no significant association between anti-erythrocyte and anti-HLA immunization.ConclusionThe erythrocyte and anti-HLA anti-immunization rates are high in our series. Preventive strategy is needed to ensure optimal blood safety.     

Stratégies d’exploration de l’allo-immunisation plaquettaire pour la prévention et la prise en charge des inefficacités transfusionnelles plaquettaires

Platelet refractoriness is a serious complication for patients receiving recurrent platelet transfusions, which can be explained by non-immune and immune causes. Human Leukocyte Antigens (HLA) allo-immunization, especially against HLA class I, is the major cause for immune platelet refractoriness. To a lesser extent, allo-antibodies against specific Human Platelet Antigen (HPA) are also involved. Pregnancy, transplantation and previous transfusions can lead to allo-immune reaction against platelet antigens. After transfusion, platelet count is decreased by accelerated platelet destruction related to antibodies fixation on incompatible platelet antigens. New laboratory tests for allo-antibodies identification were developed to improve sensibility and specificity, especially with the LUMINEX^® technology. The good use and interpretation of these antibodies assays can improve strategies for platelet refractoriness prevention and management with a patient adapted response. Compatible platelets units can be selected according to their identity with recipient typing or immune compatibility regarding HLA or HPA antibodies or HLA epitope compatibility. Prospective studies are needed to further confirm the clinical benefit of new allo-antibodies identification methods and consensus strategies for immune platelet refractoriness management.     

Pathology's historic 2019 incoming residents: Why “the internationalization of pathology” may markedly advance transfusion medicine and cellular therapeutics

ObjectivesThis study had two objectives: (1) to determine if, in the United States of America (US), the proportion of non-US citizen international medical graduates (non-US IMGs) entering pathology residencies had increased (again) in 2019 and (2) to assess how this multi-year trend might impact transfusion medicine in the US.MethodsThe most recent (2019) “National Resident Matching Program” (NRMP) data were analyzed. To assess potential future impact, using controversies related to Plasmodium falciparum (Pf) malaria, conflicting US and non-US perspectives were reviewed. Differences between published US and non-US views were identified regarding, for example, the value of Pf-resistant (“variant”) red blood cells (RBCs) and exchange transfusions.ResultsYear 2019 is the first year non-US IMGs were the largest group to fill residency-training positions for a major US specialty via the “Main Residency Match.” Also notable, US and non-US views were found to differ markedly regarding (1) the value and safety of Pf-resistant RBC variants and exchange transfusions, and (2) the threat of drug-resistant Pf-malaria parasites. Non-US clinicians and researchers seem more concerned about Pf-malaria, and their interest in cellular therapies seems greater and more optimistic.ConclusionsIn 2019, the historically high proportion of non-US IMGs among incoming pathology residents dramatically highlights the steady demographic shift that began years ago: “the internationalization of pathology” in the US. Fortunately, a review of publications related to exchange transfusion, Pf-malaria, and variant RBCs suggests non-US IMGs may markedly promote and advance cell therapies such as therapeutically-rational exchange (T-REX) of disease-resistant RBCs.     

Potential challenges faced by blood bank services during COVID-19 pandemic and their mitigative measures: The Indian scenario

The current pandemic caused by SARS-CoV-2 virus is going to be a prolonged melee. Identifying crucial areas, proactive planning, coordinated strategies and their timely implication is essential for smooth functioning of any system during a crunch.Addressing the impact of COVID-19 on transfusion services, there are 4 potential challenges viz. blood/ component shortage, donor/ staff safety, consumable supply/ logistics and catering to the convalescent plasma need. In this review article, we will be discussing about these potential challenges in detail along with the necessary mitigative steps to be adopted to tide over the COVID-19 crisis in an Indian set up.     

Characterization of circulating and cultured Tfh-like cells in sickle cell disease in relation to red blood cell alloimmunization status

BackgroundPeople living with sickle cell disease (SCD) are prone to red blood cell (RBC) alloimmunization. We hypothesized that subjects with alloantibodies (responders) would have differences in circulating T-follicular helper (Tfh)-like cells compared to subjects without alloantibodies (non-responders).Materials and methodsPeripheral blood mononuclear cells were collected from 28 subjects, including those with SCD and controls. Circulating CD4 T-cell subsets were first evaluated at baseline. CD4 T-cell subsets were also evaluated after naïve CD4 T-cells were differentiated into Tfh-like cells following in vitro culture with CD3/CD28 beads, IL-7, IL-12, and Activin A. Transfusion and alloantibody histories were extracted from the electronic medical record.ResultsNon-responders had a lower percentage of CD45RA negative Tmemory cells than responders or controls (p<0.05). Notably, there were no differences in circulating Tfh-like cells between any group. However, naïve CD4 T-cells from subjects with SCD were more likely to express CXCR5 after in vitro culture than cells from controls. After culture, CXCR5 expressing cells from responders were more likely to express PD1 and ICOS (16.43 %, sd. 20.23) compared to non-responders (3.69 %, s.d. 3.09) or controls (2.78 %, s.d. 2.04).DiscussionThe tendency for naïve CD4 T-cells from responders to differentiate into Tfh-like cells after in vitro culture may suggest these cells are prepared to assist B-cells with antibody production regardless of antigen specificity. Further studies are needed, but it is possible that these results may explain why some responders form RBC alloantibodies with multiple specificities, in addition to RBC autoantibodies and HLA alloantibodies.     

Validation of the age-adjusted shock index for pediatric casualties in Iraq and Afghanistan

Background:Pediatric casualties account for a notable proportion of encounters in the deployed setting based on the humanitarian medical care mission.Previously published data demonstrates that an age-adjust shock index may be a useful tool in predicting massive transfusion and death in children.We seek to determine if those previous findings are applicable to the deployed,combat trauma setting.Methods:We queried the Department of Defense Trauma Registry(DODTR)for all pediatric subjects admitted to US and Coalition fixed-facility hospitals in Iraq and Afghanistan from January 2007 to January 2016.This was a secondary analysis of casualties seeking to validate previously published data using the shock index,pediatric age adjusted.We then used previously published thresholds to determine patients outcome for validation by age grouping,1-3 years(1.2),4-6 years(1.2),7-12 years(1.0),13-17 years(0.9).Results:From January 2007 through January 2016 there were 3439 pediatric casualties of which 3145 had a documented heart rate and systolic pressure.Of those 502(16.0％)underwent massive transfusion and 226(7.2％)died prior to hospital discharge.Receiver operating characteristic(ROC)thresholds were inconsistent across age groups ranging from 1.0 to 1.9 with generally limited area under the curve(AUC)values for both massive transfusion and death prediction characteristics.Using the previously defined thresholds for validation,we reported sensitivity and specificity for the massive transfusion by age-group:1-3(0.73,0.35),4-6(0.63,0.60),7-12(0.80,0.57),13-17(0.77,0.62).For death,1-3(0.75,0.34),4-6(0.66-0.59),7-12(0.64,0.52),13-17(0.70,0.57).However,negative predictive values(NPV)were generally high with all greater than 0.87.Conclusions:Within the combat setting,the age-adjusted pediatric shock index had moderate sensitivity and relatively poor specificity for predicting massive transfusion and death.Better scoring systems are needed to predict resource needs prior to arrival,that perhaps include other physiologic metrics.We were unable to validate the previously published findings within the combat trauma population.     

危重病患者中的输血相关性移植物抗宿主病

目的分析ICU患者中输血相关性移植物抗宿主病(TA_GVHD)的发病情况并对影响因素进行探讨。方法女性患者输血前后自身对照,采取静脉血样,用PCR技术进行TA_GVHD插入基因片段及人Y染色体特异基因荧光检测。结果26例患者中,有14例患者输血后出现Y染色体特异基因片段检测阴性而同时TA_GVHD插入基因片段检测阳性的结果,发生率为53.8%。结论ICU中TA_GVHD发生率较文献报道明显增多,可能与ICU中危重症患者的免疫功能低下等有关。     

Neonatal RBC transfusions: Do benefits outweigh risks?

Preterm neonates represent one of the most transfused categories of patients. Their target hematocrits, however, are mainly based on expert opinion. The risk of transfusions are very high in the smallest preterm baby with a weak immune response, immature antioxidant ability, fragile germinal matrix and impaired cerebral autoregulation, yet red cell transfusions remain the only life saving measure in the baby with symptomatic anemia.Minimizing phlebotomy losses, following a restrictive transfusion policy and using screened, leukocyte depleted, irradiated, single donor blood remain the best means of avoiding the possible risks while maximizing the benefits of red cell transfusions in the preterm newborn.     

Released washed platelet concentrates are effective and safe in patients with a history of transfusion reactions

Background

Plasma removal by washing is an effective approach to prevent transfusion reactions by platelet concentrates (PCs). Recently, washed PCs were released by the Japanese Red Cross Society (JRCS).