Neonatal alloimmune thrombocytopenia due to an antibody against a labile component of human platelet antigen-3b (Bak b)

We report the second case of neonatal alloimmune thrombocytopenia due to anti-human platelet antigen (HPA)-3b (Bak(b)) antibody. The infant was severely affected with intracranial haemorrhage. Most importantly, we were able to detect this antibody only by using fresh, unfixed platelets as antigen. This antibody was detectable neither by conventional mixed passive haemagglutination, platelet immunofluorescence test using fixed platelets, nor by monoclonal antigen immobilization of platelet antigen assay using solubilized platelets. We assume that this antibody reacts only with fresh platelets and that the antigen is a labile component of HPA-3b (Bak(b)).     

Comparison of platelet antibody screen,crossmatching and HLA antibody testing in patients refractory to platelet transfusions

Patients undergoing recurrent platelet transfusions can become refractory to these transfusions. Platelet antibody screens (Immucor), platelet crossmatching assays (Immucor), and HLA antibody testing are commonly used to test these patients. The relative effectiveness of these tests has not been determined. A higher incidence of strongly positive screen results that did not predict crossmatch results was anecdotally noted. Therefore, the results of the platelet antibody screens and crossmatches were systematically compiled over a 12-year period from 2010 to 2021. Of note, the Immucor Capture-P Ready Screen (platelet antibody) had a recall in March 2013 after which the performance of the test appears to have changed. The positivity rate of the platelet antibody screen increased over the course of the study, and this was statistically significant when analyzing year as a continuous variable and when grouping years by four-year periods (2010–13,2014–17,2018–21). In contrast, platelet crossmatch reactivity decreased slightly throughout this period. During the 2018–21 period, HLA antibody testing was commonly performed and correlated well with the crossmatch testing but not with the screen. These results suggest that the drastic increase in positivity we observed in the platelet antibody screen over this period is due to increased analytic sensitivity (with possible reduced specificity) of the screen and not a change in our patient population. Based on these results, the platelet antibody screen has little clinical utility and directly performing platelet crossmatching or HLA antibody testing is recommended for patients suspected to be refractory to platelet transfusions due to alloimmune-mediated factors.     

HIV-1 infection alters gene expression in adipose tissue, which contributes to HIV- 1/HAART-associated lipodystrophy

BACKGROUND: The aetiopathogenic bases of HIV-l-/highly active antiretroviral treatment (HAART)-associated lipodystrophy (HALS) are poorly known, but this syndrome indicates that adipose tissue is highly sensitive to either HIV-1 infection, antiretroviral drugs or their combination. METHODS: To assess the relative contribution of infection and drugs, we compared the expression of marker genes corresponding to mitochondrial function, adipocyte differentiation and metabolism, and adipokines in subcutaneous adipose tissue from healthy controls, untreated HIV-1-infected patients, and HIV-1-infected patients treated with HAART with or without HALS. RESULTS: Subcutaneous adipose tissue from HIV-1-infected patients contained lower concentrations of the mRNA of the mitochondrial DNA-encoded cytochrome c oxidase subunit II than that of controls. These concentrations decreased further in association with HAART. The expression of nuclear genes coding for mitochondrial proteins, peroxisome proliferator-activated receptor-y, and adipocyte-specific markers was reduced in HIV-1-infected patients, treated or not, with respect to the controls. In contrast, the mRNA concentrations of uncoupling protein-3 and preadipocyte factor-1 increased in lipody-strophic HAART-treated patients. The genes coding for adipokines were strongly affected: tumour necrosis factor-alpha was upregulated, whereas adiponectin and leptin were downregulated in HIV-1-infected patients, treated or not. Thus, substantial alterations of gene expression were already present when naive patients were compared with controls. Further changes were associated with HAART and with the diagnosis of HALS. CONCLUSIONS: Disturbances in adipose tissue gene expression are already present in untreated HIV-1-infected patients, thus indicating a role of HIV-1 infection itself in eliciting adipose tissue alterations that are worsened by HAART, which ultimately leads to HALS.     

Autoimmune anti-HIV-1gp120 antibody with antiidiotype-like activity in sera and immune complexes of HIV-1-related immunologic thrombocytopenia.

Autoimmune antiidiotype-like antibody (Ab2) directed against anti-HIV-1gp120 (Ab1) was found in high titer in the sera of 10 consecutive homosexual and 11 narcotic addict HIV-1-related immunologic thrombocytopenia (HIV-1-ITP) patients, was barely detectable in 10 nonthrombocytopenic HIV-1 sero-positive individuals, and was not detectable in 5 normal subjects by use of a solid-phase RIA. Reactivity of autologous Ab2 for Ab1 was 4-120-fold greater than Ab2 for homologous Ab1. Affinity-purified Ab2 did not block the binding of affinity-purified Ab1 to its HIV-1gp120 epitopes on immunoblot, indicating the absence of "internal image" antiidiotype. Both Ab1 and Ab2 are precipitable from sera with polyethylene glycol (PEG) and present in a macromolecular complex that is excluded by gel filtration on G200 and contains IgG, IgM, C3, and the anti-F(ab')2 antiidiotype-like complex. PEG-precipitable complexes bind to platelets in a saturation-dependent manner. Neither affinity-purified Ab1 nor Ab2 binds to platelets. However, the combination of Ab1 and Ab2 (preincubated for 2 h at 22 degrees C) binds to platelets in a saturation-dependent manner at an optimum ratio range of 10-20:1. Ab2 reactivity correlates with serum PEG-precipitable immune complex level (r = 0.91; P less than 0.001) and with thrombocytopenia (r = 0.89; P less than 0.001). We suggest that the anti-HIV-1gp120 antiidiotype-like complex contributes to the markedly elevated platelet Ig and C3 level of HIV-1-ITP patients and propose that this may contribute to their thrombocytopenia.     

SIGN-R1 contributes to protection against lethal pneumococcal infection in mice

Rapid clearance of pathogens is essential for successful control of pyogenic bacterial infection. Previous experiments have shown that antibody to specific intracellular adhesion molecule-grabbing nonintegrin (SIGN)-R1 inhibits uptake of capsular polysaccharide by marginal zone macrophages, suggesting a role for SIGN-R1 in this process. We now demonstrate that mice lacking SIGN-R1 (a mouse homologue of human dendritic cell-SIGN receptor) are significantly more susceptible to Streptococcus pneumoniae infection and fail to clear S. pneumoniae from the circulation. Marginal zone and peritoneal macrophages show impaired bacterial recognition associated with an inability to bind T-independent type 2 antigens such as dextran. Our work represents the first evidence for a protective in vivo role for a SIGN family molecule.     

抗人血小板膜糖蛋白Ⅵ抗体的制备

目的:制备抗人血小板膜糖蛋白Ⅵ(glycoprotein Ⅵ,GPⅥ)多克隆抗体,用于建立流式细胞术(FCM)检测人血小板膜GPⅥ的方法,并观察健康人血小板表面GPⅥ表达情况.方法:以重组融合蛋白为抗原,制备抗人血小板膜GPⅥ多克隆抗体并鉴定其特异性,运用该抗体结合FCM检测101名健康受试者血小板膜GPⅥ.结果:所制备的多克隆抗体BJ010经免疫沉淀技术、ELISA双抗夹心法证实能与血小板裂解液中变性及天然血小板膜GPⅥ结合;经FCM检测证实可识别血小板膜GPⅥ.101名健康受试者血小板膜GPⅥ的平均几何荧光强度的中位数为57.7(28.8～98.0),最大值是最小值的3.5倍,性别间表达无差异.该法日内和日间变异系数分别为6.3%和8.8%.结论:成功制备获得抗人血小板膜GPⅥ多克隆抗体BJ010,并建立了FCM检测血小板膜GPⅥ的方法,该方法简单、快速,为临床研究提供了工具.     

The HIV-1 proviral landscape reveals that Nef contributes to HIV-1 persistence in effector memory CD4+ T cells

Despite long-term antiretroviral therapy (ART), HIV-1 persists within a reservoir of CD4⁺ T cells that contribute to viral rebound if treatment is interrupted. Identifying the cellular populations that contribute to the HIV-1 reservoir and understanding the mechanisms of viral persistence are necessary to achieve an effective cure. In this regard, through Full-Length Individual Proviral Sequencing, we observed that the HIV-1 proviral landscape was different and changed with time on ART across naive and memory CD4⁺ T cell subsets isolated from 24 participants. We found that the proportion of genetically intact HIV-1 proviruses was higher and persisted over time in effector memory CD4⁺ T cells when compared with naive, central, and transitional memory CD4⁺ T cells. Interestingly, we found that escape mutations remained stable over time within effector memory T cells during therapy. Finally, we provided evidence that Nef plays a role in the persistence of genetically intact HIV-1. These findings posit effector memory T cells as a key component of the HIV-1 reservoir and suggest Nef as an attractive therapeutic target.     

低值血小板标本血小板计数方法学研究

[目的] 探讨低值血小板标本血小板计数仪器法与人工法的差异。[方法] 采集68例血液病患者的低值血小板标本，仪器法用静脉血2ml于EDTA-K2抗凝管中，放置30min后，用日本Sysmex公司XE-2100五分类血细胞分析仪的光学法血小板检测方法进行检测。同时采集患者无名指毛细血管血20μl，按全国临床检验操作规程在高倍镜下进行人工法血小板计数。[结果]两种方法结果无显著性差异，P为0．755，相关性较好，相关系数为0．892，人工法较仪器法偏低1．04％。人工法与仪器法的偏差程度随血小板的减少而增加，但明显低于文献报导。[结论]采用荧光染色法的五分类血细胞分析仪（XE-2100）检测低值血小板标本结果与人工法符合良好，因其抗干扰能力强，偏差明显低于阻抗法，对指导临床，提高检测准确度起到重要作用。     

1212例就诊患者血清抗嗜肺军团菌1～14血清型抗体水平调查

目的了解我院近5年来门诊及住院患者血清嗜肺军团菌的抗体阳性率以及1～14血清型的分布特点。方法用间接免疫荧光法检测患者血清抗嗜肺军团菌血清抗体,并查询临床资料。结果1212例患者血清抗嗜肺军团菌抗体阳性163例,总阳性率为13.4%。14个血清型中,4型的抗体阳性率最高,为12.0%;其次为12型(8.5%)、5型(7.8%)、14型(6.1%)、10型(5.9%);其余血清型的抗体阳性率较低。在阳性结果中,3种血清型同时阳性最为多见,占21.0%;其次为4种或5种同时阳性。各个科室中,呼吸病科嗜肺军团菌抗体阳性检出率最高,为23.3%,其中又以4型最为多见,为19.0%,其次为12型(17.2%)。结论我院就诊患者存在不同血清型的嗜肺军团菌感染,其中以4型最为多见,不同于既往报道的西方国家1型和国内6型。嗜肺军团菌与其他病原微生物以及自身各血清型之间可能存在交叉反应,研制血清型特异的抗原用于临床检测将有助于提高抗嗜肺军团菌抗体检测的准确性。     

Relationship of platelet-associated immunoglobulin G and platelet protein to platelet size and density in normal individuals and patients with thrombocytopenia

Total platelet-associated immunoglobulin G (PA-IgG) and platelet volume and protein content in normal individuals and in patients with idiopathic thrombocytopenic purpura (ITP) and other thrombocytopenias of presumed nonimmune origin have been measured on platelets separated into subpopulations on the basis of density on continuous polyvinylpyrrolidone (Percoll) gradients. In all subjects PA-IgG per platelet was primarily found in the lightest platelets at levels up to sevenfold greater than in the heavier platelets. PA-IgG level per platelet was raised in light platelets in 29% of patients with thrombocytopenia and in heavy platelets in 60%. In almost half of these instances the PA-IgG level fell to within the normal range when considered in relation to either platelet volume or protein content. PA-IgG levels of patients with untreated ITP did not differ significantly from those with treated ITP or thrombocytopenia of other causes. Mean platelet volume and protein content of the total platelet population of all subjects showed significant linear correlation (P less than 0.01). Thus PA-IgG of both controls and patients with thrombocytopenia of all causes is preferentially located in the lightest platelets, but increases in PA-IgG in immune thrombocytopenias occur more frequently in the heavier platelets. These findings suggest that part of the process of IgG accumulation by platelets is the same in normal individuals as in patients with thrombocytopenia.     

Recombinant factor VIIa in patients with platelet function disorders or thrombocytopenia

Apart from on-label indications, recombinant factor VIIa (rFVIIa) is increasingly administered for treatment of life threatening bleeding events when appropriate standard therapy fails. Case reports and short treatment series document the efficacy and safety of rFVIIa to achieve haemostasis in patients with platelet function disorders and thrombocytopenias of various origin. An established on-label indication for the use of rFVIIa is given in patients with Glanzmann thrombasthenia with refractoriness to transfusions of platelet concentrates. Bolus applications of rFVIIa at dosages between 80 and 120 microg/kg body weight every 1.5 to 3 h are also administered successfully in patients with Bernard-Soulier syndrome, platelet storage pool defects, and other acquired platelet function disorders. In patients with Glanzmann thrombasthenia, at least three bolus injections are required to achieve effective haemostasis. In approximately half of the patients with thrombocytopenias, a single bolus of rFVIIa has been shown to be sufficient in managing otherwise untreatable bleeding complications. In these patients, haemostasis was achieved even at platelet counts <20,000/microl, although the efficacy of rFVIIa increases at higher platelet concentrations.     

Plantar feedback contributes to the regulation of leg stiffness

BACKGROUND: Running and hopping involve moving in a bouncing fashion during which the limbs behave as springs. The ability to alter the stiffness of these leg springs is essential to maintaining an efficient gait. Since the plantar surface of the foot is the only part of the body to encounter the ground during bipedal locomotion, it would seem logical that some aspect of the neurological functioning of the foot is responsible for transmission of information about the surface characteristics to the central nervous system, resulting in changes in leg stiffness. METHODS: Ten subjects (9 males, 1 female) participated in this experiment. Lidocaine was injected inferior and posterior to the lateral malleolus in order to achieve tibial nerve block at the level of the ankle. Subjects hopped at 2.2 Hz on a force plate while data were collected at 1000 Hz. Data were analyzed for peak force and leg stiffness and compared using a repeated measures ANOVA. FINDINGS: Tactile sensation, deep pressure sensation, and abductor hallucis activity displayed significant decreases following the injection, as did postural stability. Subjects demonstrated a significantly decreased leg stiffness after the nerve block (P<.01). INTERPRETATION: Plantar sensation has an effect on regulating leg mechanics in hopping. A loss of sensation in this region can exert a significant impact on the properties of the leg in gait, and future research should determine the specific pathways by which plantar feedback exerts this effect.     

网织血小板在系统性红斑狼疮患者的临床应用

目的：研究系统性红斑狼疮（SLE）患者合并血小板减少疾病的发病机制,探讨网织血小板（RP）在诊疗SLE合并血小板减少疾病中的临床应用价值。方法确诊为SLE患者55例和健康体检者50例,对SLE伴血小板减少的患者进行治疗前后检查,采用Sysmex XE-5000全自动血细胞分析仪检测网织血小板百分比（IPF）以及其他外周血细胞参数。结果 SLE患者组和正常对照组的IPF检测结果分别为（5．30＆#177;3．75）％、（2．74＆#177;1．05）％,两者比较差异有统计学意义（P＜0．05）;SLE伴血小板减少组的IPF[（10．14＆#177;3．66）％]、血小板计数（PLT）[（67．2＆#177;13．5）＆#215;109/L]、血小板平均体积（MPV）[（12．64＆#177;0．92）fL]、血小板分布宽度（PDW）[（18．24＆#177;1．70）fL]与正常对照组、SLE血小板未减少组比较,差异均有统计学意义（P＜0．05）;SLE伴血小板减少组治疗前后的IPF分别为（9．76＆#177;1．82）％和（5．86＆#177;0．96）％,两者比较差异有统计学意义（P＜0．05）。结论 SLE患者血小板减少的主要原因可能与外周血小板破坏有关,IPF的高低可以出反映骨髓血小板的生成情况,有助于疾病的辅助诊断和预后判断。     

New therapy to revert dysfunctional antibody responses during HIV-1 infection

Individuals infected with HIV-1 progress to AIDS at different rates. Rapid progressors develop AIDS within 2-5 years of initial infection, compared with approximately 10 years in typical progressors. Progression to AIDS is associated with impaired humoral and cellular immunity. In this issue of the JCI, Titanji and colleagues report that activated memory B (mBAct) cells are depleted in SIV-infected macaques defined as rapid progressors. Depletion was mediated by programmed death-1 (PD-1) and resulted in reduction of antibody titers specific for SIV and bacterial antigens. Interestingly, blockade of PD-1 in infected animals protected B cells from apoptosis and increased levels of SIV-specific antibodies in blood. These findings pave the way for a new therapeutic strategy aimed at improving humoral immunity in HIV-1 infection.