DR.lyp/lyp bone marrow maintains lymphopenia and promotes diabetes in lyp/lyp but not in +/+ recipient DR.lyp BB rats

Lymphopenia is due to a frameshift mutation in Gimap5 on rat chromosome 4 and is linked to type 1 diabetes in the diabetes prone (DP) BB rat. The hypothesis that bone marrow derived cells confer the lymphopenia phenotype was tested by reciprocal bone marrow transplantation in 40-day-old lethally irradiated diabetes resistant (DR) congenic DR.lyp/lyp (lymphopenia and diabetes) and DR.+/+ (no lymphopenia and no diabetes) rats. In two independent series of transplants, all DR.lyp/lyp rats (n=5 and 4) receiving DR.lyp/lyp bone marrow retained lymphopenia and developed insulitis (5/5 and 4/4) as well as diabetes in some (2/5 and 3/4). Both DR.+/+ and DR.lyp/lyp rats receiving DR.+/+ bone marrow cells as well as DR.+/+ rats receiving DR.lyp/lyp bone marrow cells showed no lymphopenia or diabetes. In accordance with earlier studies in non-congenic BB rats, the DR.+/+ rats receiving DR.lyp/lyp bone marrow cells recapitulated an intermediary phenotype rather than the +/+ or lyp/lyp phenotypes. Our data demonstrate that BBDP rat lymphopenia and diabetes are transferred by bone marrow transplantation to syngeneic DR.lyp/lyp but not DR.+/+ recipients. The intermediary recapitulation of DR.lyp/lyp T cells in recipient DR.+/-/+/- rats suggests that radiation resistant +/-/+/- T cells, the Gimap5 mutation in bone marrow cells, or both may not support the development of lymphopenia.     

血流感染患者外周血淋巴细胞减少的影响因素研究

背景淋巴细胞减少提示机体免疫功能下降,目前临床关于血流感染患者外周血淋巴细胞减少影响因素的研究较少。目的探讨血流感染患者外周血淋巴细胞减少的影响因素,以期为临床诊疗提供参考。方法回顾性选取2019-2020年北京市石景山医院收治的血流感染患者102例,依据患者血培养当日外周血淋巴细胞计数分为淋巴细胞减少组(外周血淋巴细胞计数<1.0×10⁹/L)69例和对照组(外周血淋巴细胞计数≥1.0×10⁹/L)33例。比较两组患者的临床资料、病原菌检出率。采用多因素Logistic回归分析探讨血流感染患者外周血淋巴细胞减少的影响因素,分析血流感染患者感染源与病原菌情况。结果两组患者性别、年龄、感染源、感染性休克发生率、压疮发生率、超敏C反应蛋白(hs-CRP)、近3个月内有住院史者所占比例、近3个月内有抗生素治疗史者所占比例、长期卧床者所占比例、气管插管者所占比例、留置导尿管者所占比例、深静脉置管者所占比例,高血压、糖尿病、冠心病、肿瘤、脑梗死、脑出血、慢性阻塞性肺疾病(COPD)、慢性支气管炎、心律失常、心功能不全、肾功能不全、高脂血症、肝损伤发生率及有外科手术史者所占比例比较,差异无统计学意义(P>0.05);淋巴细胞减少组患者PCT高于对照组(P <0.05)。两组患者革兰阳性菌、革兰阴性菌检出率比较,差异无统计学意义(P>0.05)。多因素Logistic回归分析结果显示,年龄[OR=0.949,95%CI(0.903,0.998)]、PCT[OR=1.026,95%CI(1.002,1.050)]、合并冠心病[OR=6.749,95%CI(1.429,31.868)]、肺炎克雷伯菌[OR=9.400,95%CI(1.040,84.990)]是血流感染患者淋巴细胞减少的独立影响因素(P <0.05)。金黄色葡萄球菌血流感染最常表现为肺部感染(35.7%),其次为导管相关性感染(21.4%);粪/屎肠球菌血流感染最常见于肺部感染(62.5%),其次为泌尿系统感染(25.0%);大肠埃希菌血流感染最常表现为泌尿系统感染(35.4%),其次为肺部感染(33.3%)、腹腔感染(16.7%);肺炎克雷伯杆菌血流感染最常见于肺部感染(57.7%),其次为腹腔感染(15.4%)、泌尿系统感染(15.4%);鲍曼不动杆菌血流感染最常表现于肺部感染(75.0%);铜绿假单胞菌血流感染较少见。结论血流感染患者淋巴细胞减少发生率为67.6%,年龄、PCT、合并冠心病、肺炎克雷伯菌是血流感染患者淋巴细胞减少的影响因素,尤其是肺部感染者需警惕肺炎克雷伯菌血流感染的发生。     

SARS-CoV-2-induced immunodysregulation and the need for higher clinical suspicion for co-infection and secondary infection in COVID-19 patients

Cases of co-infection and secondary infection emerging during the current Coronavirus Disease-19 (COVID-19) pandemic are a major public health concern. Such cases may result from immunodysregulation induced by the SARS-CoV-2 virus. Pandemic preparedness must include identification of disease natural history and common secondary infections to implement clinical solutions.     

T cells generated in the absence of a thoracic thymus fail to establish homeostasis

Cervical thymus mimics the thoracic thymus in supporting T‐cell development and exists in a subset of mice and humans. Importantly, it remains unknown whether the cervical thymus can generate T cells that are self‐tolerant in the complete absence of signals from the thoracic thymus. Using a fetal liver reconstitution model in thoracic thymectomized RAG^?/? mice, we found that T cells could be generated without contribution from the thoracic thymus. However, these mice had decreased T cells, increased proportions of effector memory T cells and Treg phenotype cells, increased serum IgG1/2b, and increased frequency of T cells expressing IFN‐γ, IL‐17 or IL‐10. Half of the mice that received a thoracic thymectomy and fetal liver cells, unlike sham surgery controls, developed substantial morbidity with age. Disease was associated with lymphopenia‐driven activation rather than inherent defects in the cervical thymus, as both thoracic and cervical thymocytes could generate disease in lymphopenic recipients. Administration of the homeostatic cytokine IL‐7 caused a rapid, transient increase in T‐cell numbers and reduced the time to disease onset. Together the data suggests that the cervical thymus can function in the complete absence of the thoracic thymus; however, the T cells generated do not establish homeostasis.     

Chemoradiation-Related Lymphopenia and Its Association with Survival in Patients with Squamous Cell Carcinoma of the Anal Canal

BackgroundAlthough treatment‐related lymphopenia (TRL) is common and associated with poorer survival in multiple solid malignancies, few data exist for anal cancer. We evaluated TRL and its association with survival in patients with anal cancer treated with chemoradiation (CRT).Materials and MethodsA retrospective analysis of 140 patients with nonmetastatic anal squamous cell carcinoma (SCC) treated with definitive CRT was performed. Total lymphocyte counts (TLC) at baseline and monthly intervals up to 12 months after initiating CRT were analyzed. Multivariable Cox regression analysis was performed to evaluate the association between overall survival (OS) and TRL, dichotomized by grade (G)4 TRL (<0.2k/μL) 2 months after initiating CRT. Kaplan‐Meier and log‐rank tests were used to compare OS between patients with versus without G4 TRL.ResultsMedian time of follow‐up was 55 months. Prior to CRT, 95% of patients had a normal TLC (>1k/μL). Two months after initiating CRT, there was a median of 71% reduction in TLC from baseline and 84% of patients had TRL: 11% G1, 31% G2, 34% G3, and 8% G4. On multivariable Cox model, G4 TRL at two months was associated with a 3.7‐fold increased risk of death. On log‐rank test, the 5‐year OS rate was 32% in the cohort with G4 TRL versus 86% in the cohort without G4 TRL.ConclusionTRL is common and may be another prognostic marker of OS in anal cancer patients treated with CRT. The association between TRL and OS suggests an important role of the host immunity in anal cancer outcomes.Implications for PracticeThis is the first detailed report demonstrating that standard chemoradiation (CRT) commonly results in treatment‐related lymphopenia (TRL), which may be associated with a poorer overall survival (OS) in patients with anal squamous cell carcinoma. The association between TRL and worse OS observed in this study supports the importance of host immunity in survival among patients with anal cancer. These findings encourage larger, prospective studies to further investigate TRL, its predictors, and its relationship with survival outcomes. Furthermore, the results of this study support ongoing efforts of clinical trials to investigate the potential role of immunotherapy in anal cancer.     

淋巴细胞减少及抗淋巴细胞抗体在系统性红斑狼疮中的分布及意义

目的 了解淋巴细胞减少、抗淋巴细胞抗体(ALA)在系统性红斑狼疮(SLE)中的分布及意义,并探讨ALA在淋巴细胞减少中的作用.方法 回顾性选取2003年2月至2008年2月住院的110例SLE患者作为研究对象.利用间接免疫荧光法测定上述患者的ALA.结果 ①淋巴细胞减少(＜1.5×109/L)的发生率为68.2%.淋巴细胞减少组与正常组在皮疹、浆膜炎、肾脏受累、神经系统异常、白细胞减少、抗核抗体(ANA)、抗双链DNA(dsDNA)抗体、红细胞沉降率(ESR)增快、IgG升高等方面的差异有统计学意义.淋巴细胞计数与SLE疾病活动指数(SLEDAI)评分的相关度好于白细胞计数.②ALA阻性率为46.4%,淋巴细胞减少组与健康组分别为61.3%与14.3%,两组差异具有统计学意义(P=0.000).ALA阳性组与阴性组在狼疮肾炎(LN)、神经精神性狼疮、白细胞计数、C3降低、ANA、抗dsDNA抗体、SLEDAI评分等方面差异有统计学意义.结论 淋巴细胞减少和疾病活动度显著相关.淋巴细胞减少和ALA相关,ALA可作为疾病活动的指标,并且和内脏损害及预后相关.     

尿毒症患者淋巴细胞亚群改变的研究

目的了解尿毒症患者淋巴细胞亚群的改变。方法采用血液细胞计数仪对血液细胞进行分类与计数;使用单激光三色流式细胞仪,分析带荧光标记单克隆抗体染色的淋巴细胞及其亚群。结果①血常规计数表明:尿毒症患者存在淋巴细胞减少症(P<0.005),中性粒细胞百分比高于正常对照组(P<0.005);②淋巴细胞亚群分析提示:尿毒症患者CD3 、CD4 、CD8 细胞百分数以及CD4/CD8比值,与正常对照组相比差异无显著性(P>0.05);NK细胞百分数明显增高(P<0.005),透析组CD8 细胞数较未透析组增加[(27.45±7.26)%Vs(20.33±7.01)%,P=0.042],单核细胞数高于正常对照组[(75.6±9.68)%Vs(63.98±12.82)%P=0.039];B淋巴细胞数低于正常对照组[(4.33±1.69)%Vs(9.49±3.30)%P=0.001];③尿毒症患者表现为Th2细胞优势(P<0.05),Th1/Th2比值显著降低(P<0.05),长期透析后上述表现无改善。结论尿毒症患者T细胞亚群表现为Th2优势,透析患者存在B淋巴细胞减少,淋巴细胞亚群的这些改变可能参与了血液透析患者免疫功能下降的发病机理。     

Natural Treg cells spontaneously differentiate into pathogenic helper cells in lymphopenic conditions

Induction of Forkhead‐box p3 (Foxp3) expression in developing T cells upon peptide‐MHC encountering has been proposed to define a lineage of committed Treg cells. However, sustained expression of Foxp3 is required for Treg function and what maintains Foxp3 expression in peripheral Treg remains obscure. To address this issue, we monitored natural Treg phenotype and function upon adoptive transfer into lymphocyte‐deficient mice. We first show that about 50% of Foxp3‐GFP⁺ Treg isolated from Foxp3^gfp KI animals loose Foxp3 expression in severe lymphopenic conditions. We next evidence that the cytokine IL‐2, either produced by co‐transferred conventional T cells or administrated i.v. prevents Foxp3 downregulation. Moreover, we document that Treg that lost Foxp3 expression upon adoptive transfer produce IL‐2 are not suppressive and promote tissue infiltration and damage upon secondary transfer into alymphoid mice. Our findings that Treg convert into pathogenic Th cells in absence of IL‐2 provide new clues to the success of Treg‐based immune therapies.     

Depletion of tumor‐induced Treg prior to reconstitution rescues enhanced priming of tumor‐specific,therapeutic effector T cells in lymphopenic hosts

We reported previously that vaccination of reconstituted, lymphopenic mice resulted in a higher frequency of tumor‐specific effector T cells with therapeutic activity than vaccination of normal mice. Here, we show that lymphopenic mice reconstituted with spleen cells from tumor‐bearing mice (TBM), a situation that resembles the clinical condition, failed to generate tumor‐specific T cells with therapeutic efficacy. However, depletion of CD25⁺ Treg from the spleen cells of TBM restored tumor‐specific priming and therapeutic efficacy. Adding back TBM CD25⁺ Treg to CD25^? naïve and TBM donor T cells prior to reconstitution confirmed their suppressive role. CD25⁺ Treg from TBM prevented priming of tumor‐specific T cells since subsequent depletion of CD4⁺ T cells did not restore therapeutic efficacy. This effect may not be antigen‐specific as three histologically distinct tumors generated CD25⁺ Treg that could suppress the T‐cell immune response to a melanoma vaccine. Importantly, since ex vivo depletion of CD25⁺ Treg from TBM spleen cells prior to reconstitution and vaccination fully restored the generation of therapeutic effector T cells, even in animals with established tumor burden, we have initiated a translational clinical trial of this strategy in patients with metastatic melanoma.     

Human neonatal thymectomy induces altered B‐cell responses and autoreactivity

An association between T‐cell lymphopenia and autoimmunity has long been proposed, but it remains to be elucidated whether T‐cell lymphopenia affects B‐cell responses to autoantigens. Human neonatal thymectomy (Tx) results in a decrease in T‐cell numbers and we used this model to study the development of autoreactivity. Two cohorts of neonatally thymectomized individuals were examined, a cohort of young (1–5 years post‐Tx, n = 10–27) and older children (>10 years, n = 26), and compared to healthy age‐matched controls. T‐cell and B‐cell subsets were assessed and autoantibody profiling performed. Early post‐Tx, a decrease in T‐cell numbers (2.75 × 10⁹/L vs. 0.71 × 10⁹/L) and an increased proportion of memory T cells (19.72 vs. 57.43%) were observed. The presence of autoantibodies was correlated with an increased proportion of memory T cells in thymectomized children. No differences were seen in percentages of different B‐cell subsets between the groups. The autoantigen microarray showed a skewed autoantibody response after Tx. In the cohort of older individuals, autoantibodies were present in 62% of the thymectomized children, while they were found in only 33% of the healthy controls. Overall, our data suggest that neonatal Tx skews the autoantibody profile. Preferential expansion and preservation of Treg (regulatory T) cell stability and function, may contribute to preventing autoimmune disease development after Tx.