Systemic chronic active Epstein-Barr virus infection (sCAEBV) was defined as a T- or NK-cell neoplasm in the 2017 World Health Organization (WHO) classification. To clarify the clinical features of sCAEBV under this classification and review the effects of chemotherapy, we performed a nationwide survey in Japan from 2016 through 2018 of patients with sCAEBV newly diagnosed from January 2003 through March 2016. One hundred cases were evaluated. The patients were aged 1 to 78 years (median, 21) and included 53 males and 47 females. Spontaneous regression was not observed in patients with active disease. In the childhood-onset group (age, <9 years), 78% of the patients were male. In contrast, 85% of the patients in the elderly-onset group (age, >45 years) were female. The prognosis of the childhood-onset group was better than those of the adolescent/adult- and elderly-onset groups. The main chemotherapies used were a combination of cyclosporine A, steroids, and etoposide (cooling therapy) in 52 cases and cyclophosphamide, doxorubicin, vincristine, and prednisolone (CHOP) in 45 cases. The rate of complete response (CR), defined as complete resolution of disease activity, was 17% for cooling therapy and 13% for CHOP. Virological CR was not observed. The 3-year overall survival rates in patients treated with chemotherapy only (n = 20), chemotherapy followed by allogeneic hematopoietic stem cell transplantation (allo-HSCT; n = 47), and allo-HSCT only (n = 12) were 0%, 65%, and 82%, respectively. Distinct characteristics were observed between childhood- and elderly-onset sCAEBV, and they appeared to be different disorders. Chemotherapy is currently insufficient to resolve disease activity and eradicate infected cells. The development of an effective treatment is urgently needed.

Epstein-Barr virus (EBV) causes various diseases in the elderly, including B-cell lymphoma such as Hodgkin's lymphoma and diffuse large B-cell lymphoma. Here, we show that EBV acts in trans on noninfected macrophages in the tumor through exosome secretion and augments the development of lymphomas. In a humanized mouse model, the different formation of lymphoproliferative disease (LPD) between 2 EBV strains (Akata and B95-8) was evident. Furthermore, injection of Akata-derived exosomes affected LPD severity, possibly through the regulation of macrophage phenotype in vivo. Exosomes collected from Akata-lymphoblastoid cell lines reportedly contain EBV-derived noncoding RNAs such as HI fragment A rightward transcript (BART) micro-RNAs (miRNAs) and EBV-encoded RNA. We focused on the exosome-mediated delivery of BART miRNAs. In vitro, BART miRNAs could induce the immune regulatory phenotype in macrophages characterized by the gene expressions of interleukin 10, tumor necrosis factor-α, and arginase 1, suggesting the immune regulatory role of BART miRNAs. The expression level of an EBV-encoded miRNA was strongly linked to the clinical outcomes in elderly patients with diffuse large B-cell lymphoma. These results implicate BART miRNAs as 1 of the factors regulating the severity of lymphoproliferative disease and as a diagnostic marker for EBV B-cell lymphoma.

Epstein-Barr virus (EBV) infection is usually asymptomatic and persists lifelong. Although EBV-infected B cells have the potential for unlimited proliferation, they are effectively removed by the virus-specific cytotoxic T cells, and EBV-associated lymphoproliferative disease develops only in immunocompromised hosts. Rarely, however, individuals without apparent immunodeficiency develop chronic EBV infection with persistent infectious mononucleosis-like symptoms. These patients have high EBV-DNA load in the peripheral blood and systemic clonal expansion of EBVinfected T cells or natural killer (NK) cells. Their prognosis is poor with life-threatening complications including hemophagocytic lymphohistiocytosis, organ failure, and malignant lymphomas. The term "chronic active EBV infection" (CAEBV) is now generally used for this disease. The geographical distribution of CAEBV is markedly uneven and most cases have been reported from Japan and other East Asian countries. Here we summarize the current understanding of CAEBV and describe the recent progress of CAEBV research in Japan.

Epstein-Barr virus (EBV), a ubiquitous B-lymphotropic herpesvirus, ectopically infects T or NK cells to cause severe diseases of unknown pathogenesis, including chronic active EBV infection (CAEBV) and EBV-associated hemophagocytic lymphohistiocytosis (EBV-HLH). We developed xenograft models of CAEBV and EBV-HLH by transplanting patients' PBMC to immunodeficient mice of the NOD/Shi-scid/IL-2Rγnull strain. In these models, EBV-infected T, NK, or B cells proliferated systemically and reproduced histological characteristics of the two diseases. Analysis of the TCR repertoire expression revealed that identical predominant EBV-infected T-cell clones proliferated in patients and corresponding mice transplanted with their PBMC. Expression of the EBV nuclear antigen 1 (EBNA1), the latent membrane protein 1 (LMP1), and LMP2, but not EBNA2, in the engrafted cells is consistent with the latency II program of EBV gene expression known in CAEBV. High levels of human cytokines, including IL-8, IFN-γ, and RANTES, were detected in the peripheral blood of the model mice, mirroring hypercytokinemia characteristic to both CAEBV and EBV-HLH. Transplantation of individual immunophenotypic subsets isolated from patients' PBMC as well as that of various combinations of these subsets revealed a critical role of CD4+ T cells in the engraftment of EBV-infected T and NK cells. In accordance with this finding, in vivo depletion of CD4+ T cells by the administration of the OKT4 antibody following transplantation of PBMC prevented the engraftment of EBV-infected T and NK cells. This is the first report of animal models of CAEBV and EBV-HLH that are expected to be useful tools in the development of novel therapeutic strategies for the treatment of the diseases.

A nationwide survey was conducted for identifying ataxia-telangiectasia (AT) patients in Japan. Eighty-nine patients were diagnosed between 1971 and 2006. Detailed clinical and laboratory data of 64 patients including affected siblings were collected. Analyses focused on malignancy, therapy-related toxicity, infection, and hematological/immunological parameters. The phenotypic variability of AT was assessed by comparing 26 affected siblings from 13 families. Malignancy developed in 22% of the cases and was associated with a high rate of severe therapy-related complications: chemotherapy-related cardiac toxicity in 2 children, and severe hemorrhagic cystitis requiring surgery in 2 patients. The frequency of serious viral infections correlated with the T cell count. Hypogammaglobulinemia with hyper-IgM (HIGM) was recorded in 5 patients, and 3 patients developed panhypogammaglobulinemia. Differences in immunological parameters were noted in siblings. Four patients showed an HIGM phenotype, in contrast to their siblings with normal IgG and IgM levels. The patients with HIGM phenotype showed reduced levels of TRECs and CD27+CD20+ memory B cells. The findings suggest that hitherto unidentified modifier genes or exogenous environmental factors can influence the overall immune responses. Our data along with future prospective study will lead to better understanding of the hematological/immunological phenotypes and to better care of the patients.

Imadome K‐I, Fukuda A, Kawano F, Imai Y, Ichikawa S, Mochizuki M, Shigeta T, Kakiuchi T, Sakamoto S, Kasahara M, Fujiwara S. Effective control of Epstein–Barr virus infection following pediatric liver transplantation by monitoring of viral DNA load and lymphocyte surface markers. Abstract:  EBV‐associated PTLD is a serious complication of liver transplantation. We performed periodical molecular EBV monitoring in 140 consecutive pediatric patients who had living‐related liver transplantation in the National Center for Child Health and Development, Tokyo. Sixty‐three of the 140 patients showed elevation of EBV DNA level to >102 copies/μg DNA and were further examined immunologically by flow cytometry, and the dose of tacrolimus and/or cyclosporine A was adjusted according to the results. The decrease in CD4/CD8 ratio and the increase in the number of HLA‐DR+CD8+ cells were observed in parallel with the decrease in EBV DNA load and in the number of CD19+CD23+ cells following the reduction in immunosuppressive drugs. Analysis with HLA tetramers in a patient demonstrated a dramatic increase in the number of CD8+ T cells specific to the EBV latent protein LMP2 accompanying the decline of EBV DNA load, suggesting that T cells of this specificity were actually involved in the control of EBV infection. No clinically apparent PTLD has developed in the 140 recipients, suggesting that our program of EBV control by molecular EBV monitoring coupled with lymphocyte phenotype analyses is effective in controlling EBV infection in pediatric liver transplant recipients.

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The decision to perform liver transplantation (LT) in patients with Epstein-Barr virus (EBV)-induced fulminant hepatic failure (FHF) relies on a precise assessment of laboratory and pathological findings. In this study, we analyzed clinical and laboratory data as well as the pathological features of the liver in order to evaluate the pathogenesis and the need for LT in 5 patients with EBV-induced FHF. According to the King's College criteria, the Acute Liver Failure Early Dynamic (ALFED) model, and the Japanese criteria (from the Acute Liver Failure Study Group of Japan), only 1 patient was considered to be a candidate for LT. However, explanted liver tissues in 3 cases exhibited massive hepatocellular necrosis together with diffuse CD8-positive T cell infiltration in both the portal area and the sinusoid. EBV was detected in the liver, plasma, and peripheral blood mononuclear cells (PBMNCs). In 2 cases indicated to be at moderate risk by the ALFED model, liver biopsy showed CD8-positive and EBV-encoded RNA signal-positive lymphocytic infiltration predominantly in the portal area, but massive hepatocellular necrosis was not observed. These patients were treated with immunosuppressants and etoposide under the diagnosis of EBV-induced hemophagocytic lymphohistiocytosis or systemic EBV-positive T cell lymphoproliferative disease of childhood. EBV DNA was detected at a high level in PBMNCs, although it was negative in plasma. On the basis of the pathological analysis of the explanted liver tissues, LT was proposed for the restoration of liver function and the removal of the EBV-infected lymphocytes concentrated in the liver. Detecting EBV DNA by a quantitative polymerase chain reaction in plasma and PBMNCs was informative. An accurate evaluation of the underlying pathogenesis is essential for developing a treatment strategy in patients with EBV-induced FHF. Liver Transpl 21:362-368, 2015. V C 2015 AASLD. Received July 9, 2014 accepted November 14, 2014. In the majority of patients with infectious mononucleosis, asymptomatic, self-limited hepatic dysfunction, together with mild elevations of serum aminotransferase levels (2-3 times the upper limit of normal), is usually observed. In patients with Epstein-Barr virus (EBV)-induced fulminant hepatic failure (FHF), massive hepatocellular necrosis can happen. 1-3 For such cases, liver transplantation (LT) is imperative to prevent death. 2,3