Successful outcome of severe aplastic anemia following Epstein-Barr virus infection

Virus-reactive T cells expanded in aplastic anemia eliminate hematopoietic progenitor cells by molecular mimicry

ABSTRACT

Acquired aplastic anemia is a bone marrow failure syndrome characterized by hypocellular bone marrow and peripheral blood pancytopenia. Frequent clinical responses to calcineurin inhibition and antithymocyte globulin strongly suggest critical roles for hematopoietic stem/progenitor cell-reactive T-cell clones in disease pathophysiology; however, their exact contribution and antigen specificities remain unclear. We determined differentiation states and targets of dominant T-cell clones along with their potential to eliminate hematopoietic progenitor cells in the bone marrow of 15 patients with acquired aplastic anemia. Single-cell sequencing and immunophenotyping revealed oligoclonal expansion and effector differentiation of CD8+ T-cell compartments. We reexpressed 28 dominant T-cell receptors (TCRs) of 9 patients in reporter cell lines to determine reactivity with (1) in vitro-expanded CD34+ bone marrow, (2) CD34- bone marrow, or (3) peptide pools covering immunodominant epitopes of highly prevalent viruses. Besides 5 cytomegalovirus-reactive TCRs, we identified 3 TCRs that recognized antigen presented on hematopoietic progenitor cells. T cells transduced with these TCRs eliminated hematopoietic progenitor cells of the respective patients in vitro. One progenitor cell-reactive TCR (11A5) also recognized an epitope of the Epstein-Barr virus-derived latent membrane protein 1 (LMP1) presented on HLA-A∗02:01. We identified 2 LMP1-related mimotopes within the human proteome as activating targets of TCR 11A5, providing proof of concept that molecular mimicry of viral and self-epitopes can drive T cell-mediated elimination of hematopoietic progenitor cells in aplastic anemia.

Pure red cell aplasia in a patient with trisomy X chromosome abnormality and reactivated Epstein-Barr virus infection

We describe a woman with a congenital chromosome anomaly, 47,XXX, who developed chronic pure red cell aplasia (PRCA). The patient had serologic reactivity consistent with that of reactivated Epstein-Barr virus (EBV) infection, as judged by high titers for anti-EBV viral capsid antigen (VCA) immunoglobulin G (IgG) and anti-early antigen (EA) IgG. Detection of EBV genome in peripheral blood cells and cell-free serum also supported the diagnosis. Although EBV infection has been implicated in the pathogenesis of acute PRCA, the viral infection rarely results in a chronic disease state. So far, only 1 case of EBV-associated chronic PRCA has been reported, to the best of our knowledge. Chronic PRCA also is known to occur on an autoimmune basis. Individuals carrying an extra X chromosome, such as XXY and XXX, are prone to development of immune abnormalities. Our patient had an anti-DNA autoantibody and a positive result of the direct Coombs test. The pathogenesis of PRCA in this case seemed to involve multiple factors. In addition to the infectious agent, host factors may have played a role. Although the etiologic link between chronic PRCA and trisomy X remains to be elucidated, our findings suggest the importance of karyotype analysis as well as search for infectious agents in patients with chronic PRCA.

Diagnosis of Epstein-Barr virus-associated diseases

Epstein-Barr virus (EBV) is a common DNA virus distributed worldwide. Usually the initial infection involves the upper respiratory tract without any problems and almost the entire population more than 25 years old test positive for anti-EBV antibodies. However, EBV often causes not only acute lytic infection but also chronic active infection with B cells and even T cells. In addition the EBV genome has been detected in tumors of hematopoietic or epithelial cell origin such as Burkitt's lymphomas, Hodgkin's disease, NK/T cell lymphomas, nasopharyngeal carcinomas (NPCs) and gastric adenocarcinomas. It is clearly important to make a correct diagnosis for EBV associated diseases and monitor the EBV load in individual patients for an appropriate therapy. In this paper recent advances in serological, immunological and molecular approaches for detection of EBV associated disease are described.

Successful treatment of severe aplastic anemia associated with human parvovirus B19 and Epstein-Barr virus in a healthy subject with allo-BMT

Several reports have noted pancytopenia associated with Human parvovirus B19 (PVB19) or Ebstein-Barr virus (EBV) infections in patients who have no history of immunodeficiency. To our knowledge, we report the first case of severe aplastic anemia associated with both EBV and PVB19 infections in a previously healthy 22-year-old man. He was admitted to our hematology service due to anemia and thrombocytopenia. He had no symptoms or signs of infections of these viruses. His bone marrow biopsy revealed a hypocellular marrow. Specific IgM and IgG antibodies to EBV and PVB19 were elevated. EBV and PVB19 virus genomes were detected by PCR in the bone marrow nucleated cells and the peripheral blood lymphocytes. Two months after treatment with prednisone, acyclovir, and intravenous immune globulin (IVIg), the genomes of both these viruses disappeared. However, his transfusion requirement for platelet suspensions and packed red blood cells persisted. The patient underwent allogeneic bone marrow transplant (allo-BMT) and has had an enduring complete hematological response for 8 months.

Syngeneic blood stem cell transplantation for infectious mononucleosis-related aplastic anaemia

A 17-year-old girl developed severe aplastic anaemia following an episode of infectious mononucleosis. Her identical twin sister underwent mobilization with filgrastim and subsequent leukapheresis for blood stem cell collection. The cells were freshly infused without prior immunosuppression. The patient became transfusion-independent and achieved a trilineage complete haematological response. Her engraftment lasted 6 months, but subsequently she relapsed with pancytopenia. The patient then received a second infusion of syngeneic blood stem cells, preceded by conditioning with cyclophosphamide and antithymocyte globulin. This led to durable trilineage haematological recovery still ongoing at 16 months after her second transplant.

Epstein-Barr virus associated aplastic anaemia and hepatitis

We report a Chinese girl with Epstein-Barr virus (EBV) associated aplastic anaemia and hepatitis. Epstein-Barr virus genome was demonstrated in her bone marrow cells and EBV-specific serology suggested reactivation of EBV infection. She was initially treated with anti-thymocyte globulin (ATG) and methylprednisolone but with no haematologic response, and liver function continued to deteriorate. She was then treated with acyclovir. Her aplastic anaemia improved and hepatitis resolved, and there was eradication of EBV genome from her bone marrow cells.

Epstein-Barr virus infection and associated diseases in children. II. Diagnostic and therapeutic strategies

Epstein-Barr virus (EBV), an ubiquitous human B lymphotropic virus, is the cause of infectious mononucleosis. Moreover, EBV infection can be followed by lymphoproliferative diseases in patients with inherited and acquired immunodeficiencies. Primary EBV infection may be a threat to all children after marrow or organ transplantation or those receiving chronic immunosuppressive treatment for various other reasons. The virus has been also implicated in the pathogenesis of different malignant tumours such as Burkitt lymphoma, nasopharyngeal carcinoma, Hodgkin disease and also some T-cell lymphomas. This review focuses on various aspects of virus-host interactions, immune mechanisms of the host, and the still experimental therapeutic approaches in EBV-associated diseases.

Viruses and bone marrow failure

Many agents are associated with bone marrow failure, including toxins, inherited metabolic defects, ionizing radiation, and viral infection. In most cases, the etiologic agent is unknown. Many of these unclassified cases have symptomatic, immunologic, or epidemiologic similarities to viral infections. Viruses from different taxonomic families have been implicated in bone marrow failure syndromes, and they appear to cause hematosuppression by a variety of mechanisms. Some of the viruses involved in relatively well characterized suppressive interactions will be reviewed, including parovovirus B19, dengue, hepatitis viruses, Epstein-Barr virus, cytomegalovirus and the human immunodeficiency virus.