血小板凋亡与免疫性血小板减少症关系的研究进展

<正>免疫性血小板减少症(immune thrombocytopenia,ITP)是一种获得性、高度异质性的自身免疫介导的血液系统疾病。ITP的发病机制中同时存在血小板的破坏增多和生成不足。血小板自身抗体的形成在其中发挥着重要作用。既往认为抗体引起的血小板破坏主要是依赖于网状内皮系统Fc受体介导的吞噬作用。目前研究发现,ITP还存在Fc-非依赖性血小板清除途径,如血小板自身抗体引起的血小板凋亡和血小板的去唾液酸化等[1-3]。血小板是一种无核     

新型冠状病毒疫苗的研究进展

COVID-19已经被世界卫生组织列为引起国际关注的突发公共卫生事件。目前尚没有该病的特效治疗药物。随着新型冠状病毒的不断传播以及变异,亟需寻求新型治疗措施来对抗这种病毒,积极研发新型冠状病毒疫苗十分必要。本文就目前新型冠状病毒疫苗的研究现状进行阐述、分类、分析及前景展望。     

原发免疫性血小板减少症相关性疲劳的研究进展

原发免疫性血小板减少症(primary immune thrombocytopenia,ITP)是一种获得性自身免疫性疾病[1]。近年研究发现,除典型的血小板减少和出血症状外,部分患者有明显疲劳感[1-2]。ITP相关性疲劳的界定目前尚不明确,大多数学者认为疲劳与ITP疾病本身和(或)治疗有关,具体表现为与机体能量消耗不相符、不能为睡眠或休息所缓解的乏力感。     

MicroRNAs在原发免疫性血小板减少症中作用研究进展

<正>原发免疫性血小板减少症(primary immune thrombocytopenia,ITP)是临床上常见的一种以皮肤黏膜出血为主要表现的获得性出血性疾病,占出血性疾病的1/3,严重者可发生内脏出血、颅内出血等并发症[1]。ITP的发病机制非常复杂,迄今为止具体机制仍不明确[2-3]。目前研究公认的发病机制是患者对自身抗原免疫失耐受,从而导致自身免疫介导的血小板破坏过多及巨核细胞生成血小板不足[4]。MicroRNAs(miRNAs)     

冠状病毒疫苗研究进展

进入21世纪以来,严重急性呼吸综合征冠状病毒(severe acute respiratory syndrome coronavirus, SARS-CoV)、中东呼吸综合征冠状病毒(Middle East respiratory syndromecoronavirus, MERS-CoV)及最新出现的严重急性呼吸综合征冠状病毒-2(severe acute respiratory syndrome coronavirus-2, SARS-CoV-2)等高致病性冠状病毒先后在人群中暴发流行,成为影响地区、国家乃至全球的重大公共卫生事件,研发特异性疫苗成为防控病毒流行的当务之急。本文综述了SARS-CoV和MERS-CoV疫苗的研究进展,望对SARS-CoV-2疫苗研制提供参考。     

肝素诱导的血小板减少症研究进展

肝素诱导的血小板减少（HIT）是一种由肝素诱导、免疫介导的以血小板减少和血栓形成为主要特征的药物不良反应,具有一定的致残和致死风险,死亡发生率约为5％～10％.临床研究发现,约1％～5％接受肝素治疗的患者会在应用肝素5～10天后出现HIT[1].目前临床上尚未得到充分重视,极易漏诊、误诊.我们对近年来HIT的发生机制、临床表现、诊断和治疗进展作一综述.     

免疫性血小板减少症的淋巴细胞功能研究

目的:通过测定原发免疫性血小板减少症(PITP)及继发于结缔组织病的血小板减少症(SITP)患者B细胞活化培养中细胞因子水平、血小板膜糖蛋白Ⅱb-Ⅲa(GPⅡb-Ⅲa)特异性效应B细胞和记忆B细胞频数,评价二者T、B淋巴细胞功能的异同。方法:分离、培养PITP(70例)和SITP(33例)患者的外周血单个核细胞(PBMC),应用酶联免疫斑点法(ELISPOT)检测效应B和记忆B细胞频数,采用流式微球分析法(CBA)测定培养上清的Th1/Th2/Th17细胞因子水平,对结果进行对比分析。结果:在加入B细胞刺激培养液的记忆组产生IgG的总的B细胞频数为(288.3±355.4)/105 PBMC,显著高于效应组的(28.5±54.8)/105 PBMC(P<0.01)。PITP组GPⅡb-Ⅲa特异性效应B细胞频数为(8.2±27.2)/106 PBMC,SITP组为(7.9±20.8)/106 PBMC(P=0.174);而对照组(10例)特异性效应B细胞频数为(1.0±1.1)/106 PBMC,显著低于PITP组(P=0.003)和SITP组(P=0.010)。PITP组(52例)GPⅡb-Ⅲa特异性记忆B细胞频数为(81.6±164.5)/106 PBMC,实际频数为(27.4±30.1)%,SITP组(24例)GPⅡb-Ⅲa特异性记忆B细胞频数为(23.8±43.5)/106 PBMC,实际频数为(11.0±15.1)%(均P=0.001),2组均显著高于对照组(6例)的0(均P<0.01)。CBA法测定20例PITP及14例SITP培养上清的Th1/Th2/Th17细胞因子,34例患者记忆组白细胞介素(IL)-4、IL-6、IL-10、肿瘤坏死因子(TNF)、IL-17A值均显著高于效应组(均P<0.01)。记忆组IL-4、IL-6、IL-10、TNF、IL-17A浓度与产IgG的总的记忆B细胞频数呈显著正相关(P<0.01),IL-4、IL-6、IL-10浓度与特异性记忆B细胞频数呈显著正相关(P<0.05)。PITP效应组的TNF浓度显著低于SITP(P=0.011),而记忆组的IL-4、IL-17A浓度显著高于SITP组(P=0.013和0.012)。结论:Th2细胞可能对PITP患者记忆B细胞的活化起关键作用。ELISPOT方法检测特异性GPⅡb-Ⅲa效应B细胞无法区分PITP和SITP。PITP患者特异性GPⅡb-Ⅲa记忆B细胞实际频数显著高于SITP,这可能有助于PITP和SITP的鉴别。     

免疫性血小板减少症患者血小板生成素受体激动剂的停药研究进展

免疫性血小板减少症(immune thrombocytopenia,ITP)是一种获得性自身免疫性疾病,其主要发病机制为血小板自身抗体的产生、细胞免疫和体液免疫异常活化,共同介导血小板破坏加速及巨核细胞产生血小板不足[1].ITP进展到慢性期后,发生出血的风险增加,严重影响患者的生活质量.研究表明,ITP患者生活质量和...     

Humoral response to mRNA-based COVID-19 vaccine in patients with immune thrombocytopenia

Data for COVID-19 vaccine response in patients with immune thrombocytopenia (ITP) are very limited. In a study of 28 patients with ITP, anti-severe acute respiratory syndrome coronavirus 2 spike antibody titres were measured after vaccination. The seroconversion rate for ITP patients was 91.3%, comparable to that in healthy controls (HCs). However, the antibody titre in ITP patients was significantly lower than that in HCs and declined with ageing. Furthermore, the antibody titre in ITP patients who received a minimum prednisolone dose of at least 5 mg/day at any time-point at or after initial vaccination was lower than that in other patients.     

The durability of natural infection and vaccine-induced immunity against future infection by SARS-CoV-2

The durability of vaccine-mediated immunity to SARS-CoV-2, the durations to breakthrough infection, and the optimal timings of booster vaccination are crucial knowledge for pandemic response. Here, we applied comparative evolutionary analyses to estimate the durability of immunity and the likelihood of breakthrough infections over time following vaccination by BNT162b2 (Pfizer-BioNTech), mRNA-1273 (Moderna), ChAdOx1 (Oxford-AstraZeneca), and Ad26.COV2.S (Johnson & Johnson/Janssen). We evaluated anti-Spike (S) immunoglobulin G (IgG) antibody levels elicited by each vaccine relative to natural infection. We estimated typical trajectories of waning and corresponding infection probabilities, providing the distribution of times to breakthrough infection for each vaccine under endemic conditions. Peak antibody levels elicited by messenger RNA (mRNA) vaccines mRNA-1273 and BNT1262b2 exceeded that of natural infection and are expected to typically yield more durable protection against breakthrough infections (median 29.6 mo; 5 to 95% quantiles 10.9 mo to 7.9 y) than natural infection (median 21.5 mo; 5 to 95% quantiles 3.5 mo to 7.1 y). Relative to mRNA-1273 and BNT1262b2, viral vector vaccines ChAdOx1 and Ad26.COV2.S exhibit similar peak anti-S IgG antibody responses to that from natural infection and are projected to yield lower, shorter-term protection against breakthrough infection (median 22.4 mo and 5 to 95% quantiles 4.3 mo to 7.2 y; and median 20.5 mo and 5 to 95% quantiles 2.6 mo to 7.0 y; respectively). These results leverage the tools from evolutionary biology to provide a quantitative basis for otherwise unknown parameters that are fundamental to public health policy decision-making.

The unprecedented development of efficacious vaccines against SARS-CoV-2 has represented a triumph in the global effort to control the ongoing COVID-19 pandemic. Vaccines have been shown to provide short-term protection from major adverse health outcomes of hospitalization and death (1–4). However, protection against breakthrough infection wanes (5), and breakthroughs have been extensively documented (6, 7). In response, the Food and Drug Administration advisory committee has recommended a booster of the Pfizer-BioNTech and Moderna vaccines at least 5 mo after completion of the primary series to people ≥12 and ≥18 y of age, respectively (8). A booster dose of the Johnson & Johnson/Janssen vaccine has been authorized on a faster timescale—as early as 2 mo after the single dose to individuals 18 y of age and older (8). Nevertheless, the optimal timing of boosting remains challenging to assess. Consequently, rigorous prediction of the durability of immunity conferred by vaccination against the SARS-CoV-2 virus is essential to personal and public health decision-making, having major implications regarding policy decisions about COVID-19 vaccination around the world (9, 10).Short-term longitudinal studies of SARS-CoV-2-neutralizing antibodies in vaccinated individuals (11–13) can provide information crucial to our understanding of the durability of vaccine-mediated immunity. Peak antibody responses following vaccination versus natural responses have also been quantified (14), facilitating analytical comparison of initial immune responses. For endemic viruses, longitudinal data on reinfection can provide reinfection probabilities associated with antibody level. However, longitudinal data on SARS-CoV-2 reinfection are not available during the short term associated with pandemic spread. Nevertheless, longitudinal reinfection data for a diversity of coronaviruses have been collected (15–20). SARS-CoV-2 reinfection probabilities have been obtained from them by phylogenetic analysis, using continuous ancestral and descendent state estimation (21). These estimates, produced before reinfection was commonplace, proved accurate (predicting an 18% probability of reinfection at ∼270 d [ref. 21] that was validated by a subsequent empirical finding of 18% reinfection by 275 to 300 d after primary infection [ref. 22] and, likewise, predicting a 34% probability of reinfection at ∼450 d after primary infection [ref. 21] that was validated by a subsequent empirical finding of 34% breakthrough infection 420 to 480 d after primary vaccination [ref. 23]). Similar analyses pairing antibody response and rates of waning for each vaccine with infection probabilities can enable quantification of the durability of vaccine-mediated immunity against breakthrough infections. The aim of this study is to leverage data on antibody response to each vaccine and corresponding probabilities of infection to estimate the durability of vaccine-mediated immunity against breakthrough SARS-CoV-2 infection for four well-studied vaccines: mRNA-1273, BNT162b2, ChAdOx1, and Ad26.COV2.S.     

Laboratory testing for suspected COVID-19 vaccine–induced (immune) thrombotic thrombocytopenia

COVID-19 (coronavirus disease 2019) represents a pandemic, and several vaccines have been produced to prevent infection and/or severe sequelae associated with SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2) infection. There have been several reports of infrequent post vaccine associated thrombotic events, in particular for adenovirus-based vaccines. These have variously been termed VIPIT (vaccine-induced prothrombotic immune thrombocytopenia), VITT (vaccine-induced [immune] thrombotic thrombocytopenia), VATT (vaccine-associated [immune] thrombotic thrombocytopenia), and TTS (thrombosis with thrombocytopenia syndrome). In this report, the laboratory test processes, as utilised to assess suspected VITT, are reviewed. In published reports to date, there are notable similarities and divergences in testing approaches, potentially leading to identification of slightly disparate patient cohorts. The key to appropriate identification/exclusion of VITT, and potential differentiation from heparin-induced thrombocytopenia with thrombosis (HITT), is identification of potentially differential test patterns. In summary, testing typically comprises platelet counts, D-dimer, fibrinogen, and various immunological and functional assays for platelet factor 4 (PF4) antibodies. In suspected VITT, there is a generally highly elevated level of D-dimer, thrombocytopenia, and PF4 antibodies can be identified by ELISA-based assays, but not by other immunological assays typically positive in HITT. In addition, in some functional platelet activation assays, standard doses of heparin have been identified to inhibit activation in suspected VITT, but they tend to augment activation in HITT. Conversely, it is also important to not over-diagnose VITT, given that not all cases of thrombosis post vaccination will have an immune basis and not all PF4-ELISA positive patients will be VITT.     

Vaccine-induced immune thrombotic thrombocytopenia

Vaccine-induced immune thrombotic thrombocytopenia (VITT) is primarily a complication of adenoviral vector-based covid-19 vaccination. In VITT, thrombocytopenia and thrombosis mediated by anti-platelet factor 4 (PF4) antibodies can be severe, often characterized by thrombosis at unusual sites such as the cerebral venous sinus and splanchnic circulation. Like in heparin-induced thrombocytopenia (HIT) and spontaneous HIT, VITT antibodies recognize PF4-polyanion complexes and activate PF4-treated platelets but additionally bind to un-complexed PF4, a critical finding that could be leveraged for more specific detection of VITT. Intravenous immunoglobulin and non-heparin-based anticoagulation remain the mainstay of treatment. Second dose/boosters of mRNA covid-19 vaccines appear safe in patients with adenoviral vector-associated VITT. Emerging data is consistent with the possibility that ultra-rare cases of VITT may be seen in the setting of mRNA and virus-like particle (VLP) technology-based vaccinations and until more data is available, it is prudent to consider VITT in the differential diagnosis of all post-vaccine thrombosis and thrombocytopenia reactions.     

Successful treatment of thrombotic thrombocytopenic purpura with plasmapheresis and anti-CD20 antibodies in a patient with immune thrombocytopenia and systemic lupus erythematosus: Case report

Rationale:Systemic lupus erythematosus (SLE) is an autoimmune disease of unknown etiology with diverse clinical and laboratory manifestations, including thrombocytopenia. About 25% of patients with SLE may be affected by thrombocytopenia, many of whom are asymptomatic. Some patients, however, experience platelet counts that drop quite low and predispose them to bleeding. Thrombotic thrombocytopenic purpura (TTP) is defined with a classic pentad of clinical features, such as thrombocytopenia, microangiopathic hemolytic anemia, neurological symptoms and signs, renal symptoms and signs, and fever. The association of TTP and SLE has been sporadically reported in the literature.Patient concerns and diagnosis:We describe a 16-year-old girl with SLE and immune thrombocytopenia, in whom TTP was diagnosed.Interventions and outcomes:She was treated with pulse methylprednisolone, whose platelet counts normalized after therapy with plasmapheresis and an anti-CD20 monoclonal antibody (rituximab).Conclusion:A pediatric patient with SLE and immune thrombocytopenia in whom TTP developed was treated with plasmapheresis and rituximab therapy successfully, though the patient experienced a disease relapsed after 18 months, which was controlled by the same management.     

Delayed-phase thrombocytopenia in patients with coronavirus disease 2019 (COVID-19)

Coronavirus disease 2019 (COVID-19) can affect the haematopoietic system. Thrombocytopenia at admission was prevalent, while late-phase or delayed-phase thrombocytopenia (occurred 14 days after symptom onset) is rare. This retrospective, single-centre study screened 450 COVID-19 patients and enrolled 271 patients at the Union Hospital, Wuhan, China, from January 25 to March 9, 2020. COVID-19-associated delayed-phase thrombocytopenia occurred in 11·8% of enrolling patients. The delayed-phase thrombocytopenia in COVID-19 is prone to develop in elderly patients or patients with low lymphocyte count on admission. The delayed-phase thrombocytopenia is significantly associated with increased length of hospital stay and higher mortality rate. Delayed-phase nadir platelet counts demonstrated a significantly negative correlation with B cell percentages. We also provided and described bone marrow aspiration pathology of three patients with delayed-phase thrombocytopenia, showing impaired maturation of megakaryocytes. We speculated that immune-mediated platelet destruction might account for the delayed-phase thrombocytopenia in a group of patients. In addition, clinicians need to pay attention to the delayed-phase thrombocytopenia especially at 3–4 weeks after symptom onset.