Unusual prevalence of antibodies to Epstein-Barr virus early antigen in ataxia telangiectasia

The natural history of ataxia-telangiectasia (A-T): A systematic review

BACKGROUND

Ataxia-telangiectasia is an autosomal recessive, multi-system, and life-shortening disease caused by mutations in the ataxia-telangiectasia mutated gene. Although widely reported, there are no studies that give a comprehensive picture of this intriguing condition.

OBJECTIVES

Understand the natural history of ataxia-telangiectasia (A-T), as reported in scientific literature.

SEARCH METHODS

107 search terms were identified and divided into 17 searches. Each search was performed in PubMed, Ovid SP (MEDLINE) 1946-present, OVID EMBASE 1980 -present, Web of Science core collection, Elsevier Scopus, and Cochrane Library.

SELECTION CRITERIA

All human studies that report any aspect of A-T.

DATA COLLECTION AND ANALYSIS

Search results were de-duplicated, data extracted (including author, publication year, country of origin, study design, population, participant characteristics, and clinical features). Quality of case-control and cohort studies was assessed by the Newcastle-Ottawa tool. Findings are reported descriptively and where possible data collated to report median (interquartile range, range) of outcomes of interest.

MAIN RESULTS

1314 cases reported 2134 presenting symptoms. The most common presenting symptom was abnormal gait (1160 cases; 188 studies) followed by recurrent infections in classical ataxia-telangiectasia and movement disorders in variant ataxia-telangiectasia. 687 cases reported 752 causes of death among which malignancy was the most frequently reported cause. Median (IQR, range) age of death (n = 294) was 14 years 0 months (10 years 0 months to 23 years 3 months, 1 year 3 months to 76 years 0 months).

CONCLUSIONS

This review demonstrates the multi-system involvement in A-T, confirms that neurological symptoms are the most frequent presenting features in classical A-T but variants have diverse manifestations. We found that most individuals with A-T have life limited to teenage or early adulthood. Predominance of case reports, and case series demonstrate the lack of robust evidence to determine the natural history of A-T. We recommend population-based studies to fill this evidence gap.

Serological diagnosis of Epstein-Barr virus infection: Problems and solutions

Serological tests for antibodies specific for Epstein-Barr virus (EBV) antigens are frequently used to define infection status and for the differential diagnosis of other pathogens responsible for mononucleosis syndrome. Using only three parameters [viral capsid antigen (VCA) IgG, VCA IgM and EBV nuclear antigen (EBNA)-1 IgG],it is normally possible to distinguish acute from past infection: the presence of VCA IgM and VCA IgG without EBNA-1 IgG indicates acute infection, whereas the presence of VCA IgG and EBNA-1 IgG without VCA IgM is typical of past infection. However, serological findings may sometimes be difficult to interpret as VCA IgG can be present without VCA IgM or EBNA-1 IgG in cases of acute or past infection, or all the three parameters may be detected simultaneously in the case of recent infection or during the course of reactivation. A profile of isolated EBNA-1 IgG may also create some doubts. In order to interpret these patterns correctly, it is necessary to determine IgG avidity, identify anti-EBV IgG and IgM antibodies by immunoblotting, and look for heterophile antibodies, anti-EA (D) antibodies or viral genome using molecular biology methods. These tests make it possible to define the status of the infection and solve any problems that may arise in routine laboratory practice.

Effect of cyclosporin-A (CsA) on the ability of T lymphocyte subsets to inhibit the proliferation of autologous EBV-transformed B cells

We have analyzed the effect of Cyclosporin-A (CsA) on the in vitro suppression of Epstein-Barr virus (EBV)-induced B-cell proliferations separated on the basis of cell density. CsA abolished the growth-inhibitory capacity of high-density T cells but influenced only marginally the activity of low-density lymphocytes; this suggested that different mechanisms mediate suppression in the two subsets. Stimulation with irradiated EBV-transformed cells had a different impact on the activity of low- and high-density lymphocytes. Proliferative and cytotoxic responses were inversely correlated, i.e. high-density cells proliferated but exerted low cytotoxicity, while the lytic activity of the low-density subset was stronger in the absence of significant cell proliferation. Proliferation and generation of cytotoxicity were abrogated by CsA in both subsets. The activities could be restored by addition of exogenous IL-2, suggesting that the drug may interfere with the cascade of lymphokine--cell interactions which leads to activation of immune responses. From the analysis of athe CsA effects on the two subsets it seems that the high-density one contains specific memory T cells which are activated and proliferate upon encounter with EBV-infected cells. On the other hand, low-density lymphocytes are induced to release soluble factors with antiproliferative activity. The secretory function was resistant to the suppressive effect of CsA.

Epstein-Barr virus (EBV)-specific cell-mediated and humoral immune responses in ataxia-telangectasia patients

As a part of studies on cell-mediated immune (CMI) responses of immunocompromised, Epstein-Barr virus (EBV)-infected patients who can or cannot restrict the proliferation of EBV-transformed B cells, we have studied 16 Turkish patients with ataxia-telangectasia (AT). Fifteen were EBV seropositive; one was seronegative. Among the seropositives, eight had no or only low anti-EBV-determined nuclear antigen (EBNA) antibody titers, while seven had normal anti-EBNA levels. EBV-seropositive and -seronegative healthy Turkish children were used as controls. We have particularly asked the question whether low EBNA antibody titers can be correlated with the level of EBV-specific and -nonspecific cell-mediated immunity. Non-EBV-specific tests included cell count, phenotypical characterization with monoclonal antibodies, assessment of natural killer (NK)-cell activity, and ability to suppress mitogen-induced immunoglobulin production. Two EBV-specific CMI tests were used: outgrowth inhibition (OI) and leukocyte migration inhibition (LMI). The majority of the patients of the low-EBNA antibody group was IgA deficient and had high levels of alpha-fetoprotein (a-FP). Cells reacting with OKT8 monoclonal antibody predominated in both AT patient groups. In contrast, the suppressor activity was present in only a few patients and NK and interferon-activated killing (IAK) activities were normal. EBV-specific cell-mediated responses were defective in seven of eight patients in the low-anti-EBNA group and five of seven patients in the group with normal anti-EBNA titers. It is concluded that AT patients are often defective in their EBV-specific cell-mediated immune responses and with regard to their EBNA antibody levels. These defects are associated with a predominance of T cells reacting with OKT8 monoclonal antibody.

Large granular lymphocytes inhibit the in vitro growth of autologous Epstein-Barr virus-infected B cells

The effect of lymphocyte subsets, separated on the basis of cell density, on Epstein-Barr virus (EBV)-induced B-cell proliferation was studied. The experiments were performed with lymphocytes of seropositive individuals. After 2 weeks of culture, the growth of B cells was inhibited by the T subset, which is also active in natural killer assays, i.e., the low-buoyant density lymphocyte fractions. However, if the cultures were observed for a longer time, the initial growth regressed even in cultures containing the subsets which did not have natural killing (NK) function, i.e., those with high cell density. The initial cell concentration at which the cultures were seeded determined the outcome of the experiments and the demonstration of inhibitory effects. An important difference was seen between the subsets with regard to radiosensitivity. The prompt inhibitory effect of the NK-positive subset remained after irradiation, while the function of the NK-negative one was abrogated. In the presence of the irradiated T-enriched total population, infected B cells (BEBV) grew. Consequently, the radiation-resistant effector compartment, represented by the low-density cells, was not sufficient to counteract the establishment of BEBV lines. They contributed, nevertheless, to the regression because the kinetics of B-cell growth were different in cultures containing separated high-density cells or the total population. In the former, growth continued for a longer time and complete regression occurred only in the cultures initiated with high cell concentrations. The experiments showed that two types of cells contribute to the regression of BEBV growth in cultures initiated with lymphocytes of seropositive donors. One acts promptly and is independent of cell proliferation; another is activated for proliferation by encounter with B blasts.

Epstein-Barr virus-specific antibodies in patients with adult T-cell leukemia (ATL) and healthy ATL virus-carriers

Antibodies to Epstein-Barr virus (EBV)-capsid antigen (VCA), early antigen (EA) and EBV-associated nuclear antigen (EBNA) in the sera of 103 patients with adult T-cell leukemia (ATL) and the sera of 243 age- and sex-matched healthy adults, namely 99 anti-ATLA-positive (antibodies to ATL virus-associated antigen) and 144 anti-ATLA-negative individuals, were determined by indirect immunofluorescence. The anti-VCA titers in the sera from ATL patients were within the range observed in healthy controls. Anti-EA was found in 27% of the sera from ATL patients, but in only 8% of the sera from anti-ATLA-negative healthy controls. Antibodies to EBNA, which were present in almost all healthy adults, were not found in 30% of the sera from ATL patients. Of the sera of anti-ATLA-positive healthy adult donors 11% were negative for EBNA antibody. These results suggest that functional impairment of the T-cell system in most ATL patients, and also to a lesser extent in anti-ATLA-positive adults who might be healthy ATLV-carriers, may cause an unusual immune response of antibodies to EBV-associated antigens.

Seroepidemiological study of relationships between Epstein-Barr virus and rheumatoid arthritis

To elucidate the relationship between Epstein-Barr virus (EBV) and rheumatoid arthritis (RA), we measured antibodies to RA-associated nuclear antigen (anti-RANA) and three other EBV-related antigens in the sera of RA patients and controls. Our study groups consisted of 89 patients with definite or classical RA, mean age 56, male/female ratio 47:42; and 53 normal and osteoarthritis controls, mean age 51, male/female ratio 25:28. In addition to anti-RANA, we measured antibodies to viral capsid antigen (anti-VCA), early antigen (anti-EA) and EBV-associated nuclear antigen (anti-EBNA). Anti-RANA was detected in 71% of RA patients but in only 6% of controls. Elevated anti-VCA titers (greater than 1:160) were more common in RA patients than controls, 31% compared with 15%. The geometric mean titer of anti-VCA was significantly higher iun the RA group, 133 compared with 58. Anti-EA was present in 53% of RA patients but only 19% of controls. Anti-EA in elevated titers (greater than 1:20) was present in 26% of RA patients but only 7% of controls. Characterization of the anti-EA antibodies revealed that the RA patients reacted primarily with the diffuse component, whereas the majority of the controls reacted with the restricted component of the EA complex. In contrast, the frequencies, distributions, and geometric mean titers of anti-EBNA were not significantly different between the two groups. Correlative analysis of these antibodies showed highly significant relationships between anti-VCA and anti-EA, and anti-RANA and anti-EBNA in the RA group. These data are compatible with the interpretation that RA patients have either more active EBV infections than controls or an altered regulation of their immune response to this infectious agent.

Epstein-Barr virus-related serology in marrow transplant recipients

Serial sera from 50 marrow transplant recipients were examined for their spectra and titers of antibodies to EBV-specific antigens. Immediately before or after transplant, blood products passively transferred antibodies to EB viral capsid antigen (VCA) and EBV nuclear antigen (EBNA). In most recipients, passively-transferred antibodies were replaced by endogenous antibodies regardless of whether donor or recipient had EBV antibodies before transplantation. Commencement or resumption of endogenous EBV antibody production was not associated with signs of infectious mononucleosis or heterophil antibody responses. Antibodies to VCA rose to abnormally high titers, followed successively by antibody to early antigens (EA), and disproportionately low levels of anti-EBNA. Unusually high anti-VCA and anti-EA levels persisted when tests of immune function returned to normal. Antibodies to other herpes group viruses showed no consistent changes. We conclude that (1) EBV does not cause significant clinical problems in marrow transplant recipients; (2) persistent EBV infection can become established or reestablished in the presence of antibodies to EBV; (3) marrow transplant recipients show the same exaggerated immune response to EBV as other immunodeficient patients; and (4) the pattern of EBV-specific antibodies may be a more sensitive measure of defective cell-mediated immunity than most conventional tests of immune function.