Profound granulocytopenia associated with infectious mononucleosis

Tree Shrew Is a Suitable Animal Model for the Study of Epstein Barr Virus

Epstein-Barr virus (EBV) is a human herpesvirus that latently infects approximately 95% of adults and is associated with a spectrum of human diseases including Infectious Mononucleosis and a variety of malignancies. However, understanding the pathogenesis, vaccines and antiviral drugs for EBV-associated disease has been hampered by the lack of suitable animal models. Tree shrew is a novel laboratory animal with a close phylogenetic relationship to primates, which is a critical advantage for many animal models for human disease, especially viral infections. Herein, we first identified the key residues in the CR2 receptor that bind the gp350 protein and facilitate viral entry. We found that tree shrew shares 100% sequence identity with humans in these residues, which is much higher than rabbits (50%) and rats (25%). In vitro analysis showed that B lymphocytes of tree shrews are susceptible to EBV infection and replication, as well as EBV-enhanced cell proliferation. Moreover, results of in vivo experiments show that EBV infection in tree shrews resembles EBV infection in humans. The infected animals exhibited transient fever and loss of weight accompanied by neutropenia and high viremia levels during the acute phase of the viral infection. Thereafter, tree shrews acted as asymptomatic carriers of the virus in most cases that EBV-related protein could be detected in blood and tissues. However, a resurgence of EBV infection occurred at 49 dpi. Nanopore transcriptomic sequencing of peripheral blood in EBV-infected animals revealed the dynamic changes in biological processes occurring during EBV primary infection. Importantly, we find that neutrophil function was impaired in tree shrew model as well as human Infectious Mononucleosis datasets (GSE85599 and GSE45918). In addition, retrospective case reviews suggested that neutropenia may play an important role in EBV escaping host innate immune response, leading to long-term latent infection. Our findings demonstrated that tree shrew is a suitable animal model to evaluate the mechanisms of EBV infection, and for developing vaccines and therapeutic drugs against EBV.

Infectious mononucleosis complicated by haemolytic anaemia due to the Donath Landsteiner antibody and by severe neutropenia

A young man developed infectious mononucleosis complicated by profound anaemia due to haemolysis. The Donath Landsteiner antibody was found in his serum. He was treated successfully by blood transfusion but subsequently developed severe neutropenia. Both complications have been reported previously but not in the same individual. No underlying immune deficiency could be identified.

Epstein-Barr virus in patients with chronic lymphocytic leukemia: a pilot study

The objective of this study was to assess the incidence and the clinical significance of Epstein-Barr virus (EBV) in patients with chronic lymphocytic leukemia (CLL)/small lymphocytic lymphoma (SLL). Patients with CLL/SLL who presented at The University of Texas M. D. Anderson Cancer Center over a 2-year period and had available marrow paraffin blocks were studied for evidence of EBV infection using a highly specific in-situ hybridization assay for detection of EBV encoded RNA (EBERs). Results were analysed in relation to other presenting characteristics and outcome. Thirty-two patients were examined. EBERs were detected in the bone marrow of 12 of 32 (38%) CLL/SLL marrows vs 0 of 20 normal marrows (p = 0.002). EBERs were observed in sporadic granulocytes alone or in addition to its presence in lymphocytes in nine of the 12 EBV-positive patients. EBERs were detected less frequently in patients with Rai stage 0 - 1 disease (20%) compared with Rai stage 2 - 4 (66%; p = 0.008). EBER-positive patients tended to have higher lactate dehydrogenase levels (p = 0.053). The 10-year survival rate was 22% vs 58% for patients with and without discernible EBERs (log-rank, p = 0.08). Evidence of EBV infection was found in 38% of patients with CLL/SLL. Despite the small number of patients tested, discernable EBERs were significantly more common in individuals with more advanced Rai stage and there was a trend toward shorter survival in patients in whom EBV EBERs were discerned. Larger studies are needed to determine the prognostic value and role of EBV infection in patients with CLL/SLL.

Epstein-Barr virus immunossuppression of innate immunity mediated by phagocytes

Epstein-Barr virus (EBV) is an oncogenic human herpesvirus that persistently infects approximately 90% of the world's population. Such a remarkably sustained of viral infectivity relies on EBV's ability to evade the host immune defenses. A crucial part of this anti-EBV response is mediated by cytotoxic CD8+ T lymphocytes, which maintain a life-long control over proliferating latently-infected B cells in order to prevent these from giving rise to lymphomatous diseases. On the other hand, little has been done to assess the role of phagocytes-mediated innate immunity in the pathogenesis of EBV infection. In the course of primary EBV infection, episodes of neutropenia and monocytopenia can be observed during the acute phase of infection. According to the role of those cells in the non specific and specific immunity, such a decrease in circulating phagocytes may then temporarily affect the immune defense and potentially influence the outcome of EBV infection. Recent studies have demonstrated that EBV infects both neutrophils and monocytes and modulates several of their biological functions. This review covers the current state of our knowledge relative to the role of neutrophils and monocytes in EBV pathogenesis and describes the nature of countermeasures deployed by EBV against these cells.

A practical approach to neutrophil disorders

This review discusses disorders of altered neutrophil number and function and provide a basic framework for patient evaluation and management. The sections begin with neutropenia, neutrophilia and neutrophil dysfunction with a general screening approach to differentiate common, more benign syndromes from rare, often more serious disorders. Also included is a detailed discussion of some specific primary neutrophil syndromes at the end of each section. Focus is placed on specific disorders that are clinically common or particularly instructive.

Management of severe neutropenia with cyclosporin during initial treatment of Epstein-Barr virus-related hemophagocytic lymphohistiocytosis

Severe neutropenia (absolute neutrophil count <500/gl) is probably due to the combined effects of dysregulated cytokine production and chemotherapeutic agents, and is one of the risk factors in the initial treatment of patients with Epstein-Barr virus-related hemophagocytic lymphohistiocytosis (EBV-HLH). We report here 9 cases of neutropenic HLH, of which 8 were treated with cyclosporin (CSA, 2-6 mg/kg/day; continuous infusion, or 6 mg/kg/day; per os, for periods ranging from 9 days to >8 weeks) in the initial neutropenic phase during induction treatment using corticosteroids and etoposide. Five of the 6 cases, in which CSA treatment was started early (before the second week of induction), survived the critical period with recovery of neutrophil counts within a week. The remaining 3 cases, in which CSA was introduced later or not at all, died of infection. Based on these results, we recommend a prompt short-term CSA infusion during neutropenic episodes in the most common treatment regimen of etoposide and corticosteroids in patients with HLH. Improved neutrophil recovery as a result of CSA treatment makes it possible to continue immunochemotherapy safely and obtain improved patient outcomes.

Epstein-Barr Virus Infects and Induces Apoptosis in Human Neutrophils

The role of neutrophils during Epstein-Barr virus (EBV) infection is not known. Disruption of the initial and nonspecific immune response may favor the spread of EBV infection. We have previously shown that EBV interacts with human neutrophils and modulates protein expression. In this study we have investigated the ability of EBV to infect neutrophils. Electron microscopy studies showed penetration of virus and its subsequent localization to the nucleus. The presence of viral genomes in isolated nuclei from neutrophils was also shown by polymerase chain reaction (PCR). Expression of viral transcripts like EBNA-2 (Epstein-Barr nuclear antigen-2) and ZEBRA (BamHI Z EBV replication activator) was not detected by reverse transcriptase (RT)-PCR, suggesting that EBV does not seem to establish a latent or a lytic infection in neutrophils. However, at 20 hours post-EBV infection, 77% of cells were apoptotic as compared to 22% in uninfected cell cultures, as evaluated by flow cytometry. This EBV-induced apoptosis was prevented by the addition of granulocyte-macrophage colony-stimulating factor to the cell cultures. Apoptotic cell death seems to implicate the Fas/Fas ligand (L) pathway, as reflected by an increase of Fas/Fas L expression on neutrophils treated with EBV and an increase of soluble Fas L, which may function in an autocrine/paracrine pathway to mediate cell death. Lastly, EBV genome was detected from neutrophils of infectious mononucleosis (IM) patients in contrast to neutrophils obtained from healthy EBV-seropositive donors. Our findings on the interactions of EBV with neutrophils will then provide new insights on the immunosuppressive effects associated with EBV infection.

Antineutrophil antibodies in infectious mononucleosis

Antineutrophil antibodies were detected in the serum of 12 of 14 patients with acute Epstein-Barr virus-induced infectious mononucleosis. These antibodies were present in two patients with mononucleosis and severe neutropenia, and in 10 patients with mononucleosis uncomplicated by severe neutropenia. Antineutrophil antibodies were not detected in serum from five patients with cytomegalovirus-induced mononucleosis, or five renal allograft recipients with primary or reactivation Epstein-Barr virus infection. This study suggests that antineutrophil antibodies are among those produced by the polyclonal activation induced by Epstein-Barr virus during acute infectious mononucleosis.

Infectious mononucleosis and agranulocytosis

Infectious mononucleosis is often complicated by haematological abnormalities but agranulocytosis is so rare that a causal relationship has been questioned. We here describe 2 sisters, 3 and 5 years old, who both developed agranulocytosis or profound granulocytopenia 4-5 weeks after the acute onset of mononucleosis. No contributory cause could be found and we conclude that a constitutional disposition may be responsible for this complication.

Fatal aplastic anaemia complicating infectious mononucleosis

A 7-year-old boy developed fatal aplastic anaemia, 2 weeks after the first signs of infectious mononucleosis. Although some drugs were administered, infection with the Epstein-Barr virus, leading to infectious mononucleosis, is assumed to be the cause of this aplastic anaemia. Some mechanisms possibly leading to the aplasia are discussed.