X-linked Hyper-IgM Syndrome: A Phenotype of Crohn's Disease with Hemophagocytic Lymphohistiocytosis

X-linked hyper-immunoglobulin M (IgM) syndrome is characterized by recurrent infections, low or undetectable levels of IgG and IgA, and normal to increased serum IgM, and is also rare. It is associated with mutation in the gene encoding CD40 ligand. This study aimed to describe the first international report of hemizygous CD40LG c.542G>A mutation in a 5-year-old boy with a phenotype of Crohn's disease and hemophagocytic lymphohistiocytosis. Also, the clinical implications of this mutation and associated atypical phenotype are discussed.     

异基因造血干细胞移植治疗噬血细胞综合征

噬血细胞综合征又称噬血细胞性淋巴组织细胞增生症,分为原发性和继发性两大类.对于家族性噬血细胞综合征(familial hemophagocytic lymphohistiocytosis,FHL)和难治性EB病毒相关噬血细胞综合征(EBV-HLH),异基因造血干细胞移植是目前唯一有效的治疗手段,但其鉴别诊断尤为困难,移植后多种并发症以及高病死率也受到越来越多人的关注.该文总结了近年来异基因造血干细胞移植治疗FHL和难治性EBV-HLH在诊断、预处理方案、移植后并发症、死亡原因分析及预后等方面的研究进展.     

显著高铁蛋白血症与噬血细胞性淋巴组织细胞增多症的相互关系

目的: 探讨显著高铁蛋白血症(marked hyperferritinemia,MHF)与噬血细胞性淋巴组织细胞增多症(hemophagocytic lymphohistiocytosis,HLH)患者的临床特征以及相关性。方法: 回顾性收集北京大学人民医院2017年1月至2018年9月急诊及住院的MHF患者的临床资料,包括患者一般资料,症状体征,血常规、生化、出凝血检测、血清铁蛋白检查,以及自然杀伤(natural killer, NK)细胞活性、可溶性白介素(interleukin, IL)-2受体、骨髓检查等。按是否诊断为HLH分为HLH组和非HLH组,按随访3个月结局分为死亡组与存活组,分别对各组进行比较分析。结果: 123例MHF患者平均年龄为(44.2±17.4)岁,男女比例为1.3 ∶1;常见病因为血液肿瘤、风湿免疫性疾病、铁超载、HLH。随着铁蛋白水平升高,HLH患者比例增加,铁蛋白在10 000~19 999、20 000~29 999、30 000~39 999、40 000~49 999、50 000 μg/L以上时,HLH占比分别为28.8%、40.0%、54.5%、50.0%、50.0%。HLH共46例(37.4%), 继发于肿瘤15例、风湿免疫性疾病14例、感染性疾病2例,不明原因15例。HLH组与非HLH组比较,两组间在年龄、性别、发热、意识障碍、初始铁蛋白、最高铁蛋白、血细胞改变、谷丙转氨酶(alanine aminotransferase, ALT)、谷草转氨酶(aspartate aminotransferase, AST)、总胆红素(total bilirubin,TBIL)、直接胆红素(direct bilirubin DBIL)、甘油三酯(triglyceride, TG)方面差异无统计学意义(P>0.05), 出凝血检测除纤维蛋白原(fibrinogen, Fib)外,差异也无统计学意义(P>0.05),在死亡率方面两组间差异无统计学意义(P>0.05);而在肝、脾、淋巴结肿大,白蛋白(albumin, ALB),Fib方面两组间差异有统计学意义(P<0.05)。死亡组与存活组比较,两组间在年龄,性别,发热,肝、脾、淋巴结肿大,初始铁蛋白,最高铁蛋白,中性粒细胞(neutrophil, Neu),血红蛋白(hemoglobin, Hb),ALT,AST,ALB,TG方面差异无统计学意义(P>0.05),出凝血检测除凝血酶原时间(prothrombin time, PT)外,两组间差异无统计学意义(P>0.05), HLH所占比例两组间差异也无统计学意义(P>0.05),而在意识障碍、血小板计数(platelet, PLT)、PT、TBIL、DBIL方面两组间差异有统计学意义(P<0.05)。结论: 随着铁蛋白水平升高,HLH患者的比例随之增加,但是MHF对于HLH诊断不具有特异性。     

Macrophage Activation Syndrome-Associated Markers in Severe Dengue

Hemophagocytosis, a phenomenon of which activated macrophages phagocytosed hematopoietic elements was reportedly observed in severe dengue patients. In the present study, we investigated whether markers of macrophage activation syndrome (MAS) can be used as differential diagnostic markers of severe dengue. Two hundred and eight confirmed dengue patients were recruited for the study. Sandwich ELISA was used to determine serum ferritin, soluble CD163 (sCD163), and soluble CD25 (sCD25) levels. The population of circulating CD163 (mCD163) monocytes was determined using flow cytometry. Receiver operating characteristic (ROC) analysis was plotted to determine the predictive validity of the biomarkers. Serum ferritin and sCD163 were found significantly increased in severe dengue patients compared to dengue fever patients (P = 0.003). A fair area under ROC curves (AUC) at 0.72 with a significant P value of 0.004 was observed for sCD163. sCD25 and mCD163 levels were not significantly different between severe dengue and dengue fever patients. Our findings suggest that in addition to serum ferritin, sCD163 can differentiate severe dengue from that of dengue fever patients. Hence, sCD163 level can be considered for use as a predictive marker for impending severe dengue.     

Liver-associated immune abnormalities

In recent years, the cross talk between the liver and the immune system is being uncovered, in part by studying liver involvement in primary immune deficiencies (PID) and in part by investigating the alterations of the immune system following orthotopic liver transplantation (OLT). Here we review some of the reciprocal interactions between the liver and the immune system. Patients with PID, particularly those involving inherited defects in T and B cells or innate immunity are prone to infections and inflammatory responses that often involve the liver. Omenn's syndrome, familial hemophagocytic lymphohistiocytosis, AIRE, FOXP3 and CD25 deficiencies, common variable immunodeficiency, CD40 ligand deficiency, chronic granulomatous disease and autoimmune lymphoproliferative syndrome are some of the notable PID associated with typical hepatobiliary abnormalities. Knowledge gained from studying these PID together with laboratory and histological evaluations can assist in managing PID-associated liver dysfunction. The liver itself also has important effects on the immune system, as evident from the growing experience with patients surviving OLT. Up to 40% of pediatric patients who receive OLT suffer from post transplantation allergy, autoimmunity, and immune-mediated disorders (PTAA). PTAA is more common after liver and heart transplantations than kidney transplantations. Potential contributing factors for the increased frequency of PTAA after OLT include the age of the patients, the prolonged use of tacrolimus and the reduced regulatory immune function with a shift towards a TH2 immune response. Better understanding of the mechanisms leading to the development of PTAA after OLT will also improve the management of these conditions.     

Signaling pathways involved in the T‐cell‐mediated immunity against Epstein‐Barr virus: Lessons from genetic diseases

Primary immunodeficiencies (PIDs) provide researchers with unique models to understand in vivo immune responses in general and immunity to infections in particular. In humans, impaired immune control of Epstein‐Barr virus (EBV) infection is associated with the occurrence of several different immunopathologic conditions; these include non‐malignant and malignant B‐cell lymphoproliferative disorders, hemophagocytic lymphohistiocytosis (HLH), a severe inflammatory condition, and a chronic acute EBV infection of T cells. Studies of PIDs associated with a predisposition to develop severe, chronic EBV infections have led to the identification of key components of immunity to EBV – notably the central role of T‐cell expansion and its regulation in the pathophysiology of EBV‐associated diseases. On one hand, the defective expansion of EBV‐specific CD8 T cells results from mutations in genes involved in T‐cell activation (such as RASGRP1, MAGT1, and ITK), DNA metabolism (CTPS1) or co‐stimulatory pathways (CD70, CD27, and TNFSFR9 (also known as CD137/4‐1BB)) leads to impaired elimination of proliferating EBV‐infected B cells and the occurrence of lymphoma. On the other hand, protracted T‐cell expansion and activation after the defective killing of EBV‐infected B cells is caused by genetic defects in the components of the lytic granule exocytosis pathway or in the small adapter protein SH2D1A (also known as SAP), a key activator of T‐ and NK cell‐cytotoxicity. In this setting, the persistence of EBV‐infected cells results in HLH, a condition characterized by unleashed T‐cell and macrophage activation. Moreover, genetic defects causing selective vulnerability to EBV infection have highlighted the role of co‐receptor molecules (CD27, CD137, and SLAM‐R) selectively involved in immune responses against infected B cells via specific T‐B cell interactions.     

Clinicopathological findings of virus-associated hemophagocytic syndrome in bone marrow: Association with Epstein-Barr virus and apoptosis

Non-neoplastic hemophagocytic syndrome (HPS), also called virus-associated hemophagocytic syndrome (VAHS), has been thought to be a distinct clinical entity. A spontaneous recovery is common, but the prognosis of Epstein-Barr virus (EBV)-associated VAHS is poor. However, the role of EBV has yet to be clearly elucidated. A retrospective study of the bone marrow of 30 cases, in which the diagnosis of non-neoplastic VAHS was clinicopathologically confirmed, was performed. We were unable to histologically confirm the presence of neoplastic lesions, especially lymphoma cell infiltration. Ten of the patients were children (aged less than 15 years) and young adults (aged under 20 years; median age, 10 years). Twenty patients were adults (aged over 21 years; median age, 48 years). Twelve of these patients died, while 18 showed a spontaneous recovery. We performed immunological staining and in situ hybridization (ISH) for EBV. To clarify the presence of apoptosis, an in situ apoptosis detection (tunnel) method was used. In situ hydridization showed an EBV-presence in 16 of the 30 patients. In addition, the EBV-presence was confined in the lymphocytes, especially T lymphocytes in double stainings. The number of EBV-infected cells varied; however, the EBV presence was associated with ages. Nine of the 10 children and young adults showed an EBV-presence, while EBV was detected in seven of the 20 adults. Especially in 10 patients aged over 49 years, no EBV was detected. According to the in situ apoptosis detection, apoptotic cells were increased in number and considered to be lymphoid cells, but not myeloid or histiocytic cells. Some apoptotic cells were phagocyted with histiocytes. Histologically, apoptosis may be one of the factors that induced phagocytosis.     

Induction of apoptosis and caspase activation in cells obtained from familial haemophagocytic lymphohistiocytosis patients

Familial haemophagocytic lymphohistiocytosis (FHL) is a rare and uniformly fatal disorder of early childhood characterized by fever, hepatosplenomegaly, cytopenia and widespread infiltration of vital organs by activated lymphocytes and macrophages. In order to test whether the massive accumulation of immune cells in these patients is associated with a perturbation of apoptosis, lymphocytes were isolated from eight patients and subjected to the chemotherapeutic agent etoposide or agonistic anti-Fas monoclonal antibodies in vitro. These stimuli elicited a normal apoptotic response in FHL patient cells when compared to healthy controls, as determined by phosphatidylserine exposure, DNA fragmentation, in vitro cleavage of the caspase-3-like substrate aspartate-glutamate-valine-aspartate-7-amino-4-methyl-coumarin (DEVD-AMC) and proteolysis of the anti-apoptotic protein Bcl-2. In addition, the degree of constitutive and Fas-triggered apoptosis in freshly isolated neutrophils was monitored in three children, with similar results. These studies indicate that immune cells derived from FHL patients are not inherently resistant to apoptosis induction. Specifically, etoposide-induced and Fas-triggered activation of intracellular caspases appears to remain intact in these individuals. However, the degree of spontaneous activation of caspase-3-like enzymes in activated lymphocytes was attenuated in three of the four patients tested prior to initiation of therapy, suggesting a possible biological deficiency in these individuals.