The effect of rituximab on anti‐platelet autoantibody levels in patients with immune thrombocytopenia

Rituximab is an effective therapy resulting in a platelet count improvement in 60% of patients with immune thrombocytopenia (ITP). Rituximab depletes B cells; thus, a reduction in platelet autoantibody levels would be anticipated in patients who achieve a clinical response to this treatment. The objectives of this study were to determine whether rituximab was associated with a reduction in platelet autoantibody levels, and to correlate the loss of autoantibodies with the achievement of a treatment response. We performed a case‐control study nested within a previous randomized controlled trial of standard therapy plus adjuvant rituximab or placebo. We measured platelet‐bound anti‐glycoprotein (GP) IIbIIIa and anti‐GPIbIX using the antigen capture test. Of 55 evaluable patients, 25 (45%) had a detectable platelet autoantibody at baseline. Rituximab was associated with a significant reduction in anti‐GPIIbIIIa levels (P = 0·02) but not anti‐GPIbIX levels (P = 0·51) compared with placebo. Neither the presence of an autoantibody at baseline nor the loss of the autoantibody after treatment was associated with a response to rituximab. The subset of patients with persistent autoantibodies after treatment failed to achieve a platelet count response, suggesting that persistence of platelet autoantibodies can be a marker of disease severity.     

Heparin-Induced Thrombocytopenia and Vascular Surgery

Heparin-induced thrombocytopenia (HIT) is of special interest to vascular surgeons as heparin is the predominant anticoagulant used before, during, and after vascular surgery. Further, the prothrombotic nature of this antibody-mediated disorder leads to a high frequency of limb ischemia due to large arterial occlusion by platelet-rich (“white”) clots or because of extensive venous thrombosis involving large veins and small venules. This latter syndrome has been associated with coumarin anticoagulation of HIT-associated deep-vein thrombosis (coumarin-induced venous limb gangrene). Non-heparin anticoagulants, such as the direct thrombin inhibitors (lepirudin, argatroban), may be needed for intraoperative management of a patient with suspected acute HIT who requires vascular surgery. The transience of HIT antibodies provides a rationale for intraoperative use of heparin in a patient who has recovered from HIT and in whom HIT antibodies are no longer detectable.     

Immune thrombocytopenia following immunisation with Vaxzevria ChadOx1-S (AstraZeneca) vaccine,Victoria, Australia

Emerging evidence suggest a possible association between immune thrombocytopenia (ITP) and some formulations of COVID-19 vaccine. We conducted a retrospective case series of ITP following vaccination with Vaxzevria ChadOx1-S (AstraZeneca) and mRNA Comirnaty BNT162b2 COVID-19 (Pfizer-BioNTech) vaccines and compare the incidence to expected background rates for Victoria during the first six months of the Australian COVID-19 vaccination roll-out in 2021. Cases were identified by reports to the Victorian state vaccine safety service, SAEFVIC, of individuals aged 18 years or older presenting with thrombocytopenia following COVID-19 vaccination without evidence of thrombosis. Twenty-one confirmed or probable cases of ITP were identified following receipt of AstraZeneca (n = 17) or Pfizer-BioNTech (n = 4) vaccines. This translates to an observed incidence of 8 per million doses for AstraZeneca vaccine, twice the expected background rate of 4.1 per million. The observed rate for Pfizer-BioNTech was consistent with the expected background rate. The median time to onset for the cases post AstraZeneca vaccination was 10 days (range 1–78) and median platelet nadir 5 × 10⁹/L (range 0–67 × 10⁹/L). Hospital presentations or admissions for management of symptoms such as bleeding occurred in 18 (86%) of the cases. The majority of cases (n = 11) required intervention with at least 2 therapy modalities. In conclusion, we observed a substantially higher than expected rate of ITP following AstraZeneca vaccination. ITP is the second haematological adverse event, distinct from that of thrombosis with thrombocytopenia syndrome (TTS), observed following AstraZeneca vaccination.     

Extensive severe fever with thrombocytopenia syndrome virus contamination in surrounding environment in patient rooms

ObjectivesSevere fever with thrombocytopenia syndrome (SFTS) is an emerging tick-borne disease in Korea and China. Although there is previous evidence of person-to-person transmission via direct contact with body fluids, the role of environmental contamination by SFTS virus (SFTSV) in healthcare settings has not been established. We therefore investigated the contamination of the healthcare environment by SFTSV.MethodsWe investigated the possible contamination of hospital air and surfaces with SFTSV transmission by collecting air and swabbing environmental surface samples in two hospitals treating six SFTS patients between March and September 2017. The samples were tested using real-time RT-PCR for SFTS M and S segments.ResultsOf the six SFTS patients, four received mechanical ventilation and three died. Five rooms were occupied by those using mechanical ventilation or total plasma exchange therapy in isolation rooms without negative pressure and one room was occupied by a patient bedridden due to SFTS. SFTSV was detected in 14 (21%) of 67 swab samples. Five of 24 swab samples were obtained from fomites including stethoscopes, and 9 of 43 were obtained from fixed structures including doorknobs and bed guardrails. Some samples from fixed structures such as television monitors and sink tables were obtained in areas remote from the patients. SFTSV RNA was not detected in five air samples from three patients' rooms.ConclusionsOur data suggest that SFTSV contamination was extensive in surrounding environments in SFTS patients' rooms. Therefore, more strict isolation methods and disinfecting procedures should be considered when managing SFTS patients.     

Heparin-induced thrombocytopenia associated with pulmonary embolism after total knee arthroplasty： a case report and review of literatures

Type II heparin-induced thrombocytopenia (HIT) is a life-threatening adverse drug reaction initiated by heparin administration. We described a rare case of LMWH-induced HIT complicated with proven pulmonary embolism (PE) in a 75-year-old male patient who hospitalized with diagnose of right knee osteoarthritis and was underwent total knee arthroplasty. The patient was successfully treated with argatroban. Early recognition and timely alternative therapy are of great importance in the treatment of this severe disorder.     

Prise en charge des grossesses à risque dans un contexte d’incompatibilité fœto-maternelle plaquettaire et/ou d’allo-immunisation : avis du groupe d’experts du GFHT (Groupe français d’études sur l’hémostase et la thrombose)

IntroductionFetal and neonatal alloimmune thrombocytopenia (FNAIT) is a potentially devastating disease, seen in 1/800–1000 neonates. FNAIT is the most common cause of early-onset isolated severe neonatal thrombocytopenia in maternity wards. A working group on fetomaternal platelet alloimmunization was created in 2017, under the auspices on the French Group of Thrombosis and Hemostasis (GFHT).ObjectivesThe objective was to survey clinical practices for management of high-risk pregnancies in a context of suspected or confirmed FNAIT.MethodsRecommendations published by the ICTMG were translated in French, and discussed (Fetal and neonatal alloimmune thrombocytopenia: recommendations for evidence-based practice, an international approach. British J of Haematology, 2019, 185, 549–562).ResultsThe study involved centers from France, Switzerland and Belgium: Angers, Besançon, Bordeaux, Brest, Créteil/Clamart, Genève, Grenoble, Liège, Lille, Lyon, Marseille, Nantes, Nîmes, Paris (hôpitaux Necker, Robert Debré et Trousseau), Poitiers, Rennes, Saint-Etienne, Strasbourg, Toulouse, Tours.ConclusionsExpert opinion was validated on September 23, 2020 (consensus ≥ 90%).     

Molecular basis of inherited thrombocytopenias

Inherited thrombocytopenias (IT) are a heterogeneous group of diseases caused by at least 20 different genes. At present, these genes account for approximately 50% of cases, suggesting that novel genes have yet to be identified for a comprehensive understanding of platelet biogenesis defects. This review provides an update of ITs focusing on the molecular basis and potential pathogenic mechanisms affecting megakaryopoiesis and platelet production.     

发热伴血小板减少综合征研究热点的可视化分析

[摘要]　目的　对发热伴血小板减少综合征（severe fever with thrombocytopenia syndrome, SFTS）的相关文献进行文献计量学和可视化分析，探寻近年来的研究现状、热点及趋势，为临床治疗和基础研究提供参考。方法?以Web of Science（WOS）核心合集和中国知网（China national knowledge infrastructure, CNKI）数据库为文献来源，检索2011年1月1日—2021年12月31日有关SFTS的文献，导入CiteSpace.5.7.R2软件，以国家、作者、文献共被引、关键词为节点进行可视化分析，并绘制相关图谱。结果?在WOS核心合集共检索到797篇文献，在CNKI数据库共检索到714篇文献。相关领域发文量总体呈上升趋势，中国发文量居首位，美国和日本之间机构合作密切。研究热点集中在发病机制、抗体、特异性治疗等领域。非结构蛋白、临床预后、血小板减少、SFTS感染的靶细胞等将是未来的研究重点。结论?国内外关于SFTS的研究逐渐成熟，新型布尼亚病毒、免疫功能、预后是研究重点，但是对SFTS发病机制和病毒受体尚不清楚，仍须进一步探索。