Detection of primary Epstein-Barr virus infection in a patient with X-linked lymphoproliferative disease receiving immunoglobulin prophylaxis

Pathogenesis and diagnosis of X-linked lymphoproliferative disease

X-linked lymphoproliferative syndrome (XLP) is a rare, often fatal, primary immunodeficiency that has profound and damaging effects on the immune system of affected individuals. It is characterized by a dysregulated immune response, most commonly to Epstein-Barr viral infection. The defective gene in this syndrome has been identified as SAP-SLAM (signaling lymphocyte activation molecule)-associated protein. It is an adapter molecule that is required for appropriate function of the SLAM-related receptors. There is now a greater understanding of the molecular associations and cellular pathogenesis of SAP and this review will summarize the most recent findings. Clinically, XLP may be difficult to diagnose as a result of its varied clinical phenotype, and protein and genetic assays are currently used to make a definitive diagnosis. With the advances in gene analysis and genomics technology, it is likely that better and more rapid diagnostic techniques will become available.

Advanced therapeutic and prophylactic strategies for Epstein-Barr virus infection in immunocompromised patients

Epstein-Barr virus (EBV) is an ubiquitous human herpesvirus. Primary infection is generally subclinical but in certain circumstances, such as in patients with either hereditary or secondary immunodeficiency, EBV infection may cause overt disease that is often lethal. Strategies for the prophylaxis and treatment of these potentially life-threatening complications of EBV infection have advanced dramatically. They include immunological-based approaches targeted at EBV-infected cells, as well as improvement in the treatment of the underlying and predisposing disease. This review will discuss EBV biology and immune events that occur in both immunocompetent and immunocompromised individuals and introduce the novel prophylactic and therapeutic strategies for EBV-associated life-threatening diseases.

Loss of circulating CD27+ memory B cells and CCR4+ T cells occurring in association with elevated EBV loads in XLP patients surviving primary EBV infection

Detailed longitudinal studies of patients with X-linked lymphoproliferative disease (XLP) may increase our understanding of the immunologic defects that contribute to the development of lymphoma and hypogammaglobulinemia in XLP. We describe progressive changes observed in immunoglobulin concentrations, lymphocyte subsets, and Epstein-Barr virus (EBV) loads occurring in a 2-year period in a newly infected, but otherwise healthy, carrier (patient 9). We compare these findings with those observed in the patient's brother, who had hypogammaglobulinemia and XLP (patient 4). Immunoglobulin G (IgG), IgM, and IgA concentrations increased in patient 9 during acute EBV infection, but thereafter they decreased steadily to concentrations consistent with hypogammaglobulinemia, reaching a plateau 5 months after infection. In both patients, CD19+ B-lymphocyte rates remained lower than 3%, with a contraction of the B-cell memory compartment (CD27+ CD19+/CD19+) to 20% (normal range, 32%-56%). T-lymphocyte subpopulations showed a reduction in CD4+ T-cell counts and a permanent CD8+ T-cell expansion. Interestingly, CXCR3 memory TH1 cells were expanded and CCR4+ TH2 lymphocytes were reduced, suggesting that abnormal skewing of memory T-cell subsets might contribute to reduced antibody synthesis. Despite an expanded number of CD3+CD8+ lymphocytes, increased EBV loads occurred in both patients without overt clinical symptoms of mononucleosis, lymphoproliferative disease, or lymphoma.

Epstein-Barr virus in patients with immunodeficiency disorders

The Epstein-Barr virus (EBV), one of eight known human herpesviruses, causes a wide spectrum of diseases under certain conditions. In particular, in the setting of immunodeficiency, which includes primary or secondary/acquired immunodeficiencies, they have been increasingly reported. The major clinical phenotype is the EBV genome-positive lymphoproliferative disorder, which ranges from benign lymphoproliferation to malignant lymphoma with cytogenetic alterations. Severe or fatal infectious mononucleosis may develop in some patients with immunodeficiencies such as X-linked lymphoproliferative disease.

Decreased cytoplasmic immunoglobulin A production during Epstein-Barr virus immortalization on lymphocytes from patients with ataxia-telangiectasia

Previously, we have reported significantly lower immunoglobulin (Ig) A production in supernatants of cultured lymphoblastoid cells using enzyme-linked immunosorbent assay from patients with ataxia-telangiectasia (AT) when compared to that of age- and sex-matched healthy individuals. Here, we further assess the degree of cytoplasmic Ig production in these cells and also analyze it during the early phase of Epstein-Barr virus immortalization. All classes of cytoplasmic IgM, IgG, and IgA productions were demonstrated in cells from healthy controls. In contrast, cells from patients with AT showed only cytoplasmic IgM and IgG with low or nondetectable levels of IgA during and after the immortalizing process. These results suggest B lymphocytes bearing IgA are functionally immature and/or defective in patients with AT.

Primary immunodeficiency diseases and Epstein-Barr virus-induced lymphoproliferative disorders

Increased incidence of malignant disorders is noted in patients with both primary and acquired immunodeficiency diseases. The pathogenetic mechanism(s) for these disorders remain unclear. Defective immunosurveillance of these patients, however, is mainly postulated to be responsible for the increased risk of these malignant disorders. Of the malignant disorders, Epstein-Barr virus (EBV)-induced lymphoproliferative disorders (LPD) have been increasingly reported, possibly due to improved therapeutic management techniques such as bone marrow transplantation, which results in prolonged survival periods for the primary immunodeficiency; the dramatic development of immunosuppressive treatments for transplant recipients; and the growing numbers of acquired immunodeficiency syndrome (AIDS) patients. This review focuses on the primary immunodeficiency diseases and EBV-induced LPD, and discusses pathogenetic mechanism(s) for the increased incidence of these malignant disorders.