Baarle, D. van

Adequate control of primary EBV infection and subsequent reactivations after cardiac transplantation in an EBV seronegative patient (Article)

2012-08-01T00:00:00Z

EBV seronegative recipients of cardiac transplantation are at risk for development of post transplant lymphoproliferative disease following primary EBV infection due to the ongoing treatment with immunosuppressive drugs. Here we present detailed kinetics of the EBV-specific T-cell response following cardiac transplantation in an EBV seronegative recipient who developed a primary EBV infection 15weeks post transplantation and subsequent viral reactivations throughout follow up. The patient developed an EBV-specific CD8+T-cell response within 24days after first detection of the primary infection. Subsequently, an increased EBV-specific CD8+T-cell response developed upon viral reactivation, indicated by a threefold increase of EBV-specific CD8+T cells and increased IFNy production after stimulation with EBV-specific peptide pools. These data indicate that an EBV-specific T-cell response capable of adequate control of a primary EBV-infection and subsequent viral reactivations can develop in an EBV seronegative cardiac transplant recipient in the presence of severe immunosuppression.

Guiding the action of the immune system: Interactions between the immune system and non-immune tissues. NVVI-Dutch society for Immunology Course, Lunteren, March 31st-April 1st, 2010 (Article)

2011-07-01T00:00:00Z

Influence of donor cytomegalovirus (CMV) status on severity of viral reactivation after allogeneic stem cell transplantation in CMV-seropositive recipients (Article)

2011-04-01T00:00:00Z

We investigated the role of donor cytomegalovirus (CMV) serostatus on reactivation of CMV infection in CMV-infected transplant recipients. Reactivation of CMV infection occurred more frequently in patients receiving a CMV-positive graft but was less severe than in patients receiving a CMV-negative graft. These data suggest roles for both virus as well as CMV-specific immunity present in the graft.

T-cell responses at baseline and during therapy with peginterferon-α and ribavirin are not associated with outcome in chronic hepatitis C infected patients (Article)

2010-09-01T00:00:00Z

Background: Since the association between hepatitis C virus (HCV)-specific T-cell responses both pre-treatment and during interferon-α based therapy and viral clearance is unresolved, a combined analysis of distinctive T-cell characteristics (proliferation and interferon-γ production) is important to clarify this issue. Methods: Peripheral blood mononuclear cells (PBMC) collected in 22 chronic HCV infected patients at pre-treatment and at week 4 during pegIFN-α/ribavirin therapy, were stimulated with overlapping peptide pools in a [3H]-thymidine assay, an interferon-γ-ELISA, and a sensitive 12-day T-cell expansion assay. Results: Compared to the [3H]-thymidine proliferation and interferon-γ secretion assays, the 12-day T-cell expansion assay was more sensitive in detecting T-cell responses. No significant association was demonstrated between pre-treatment HCV-specific CD4+ or CD8+ T-cell responses and either a sustained virological response (SVR) or a rapid virological response (RVR). However, a skewing of individual responses towards the non-structural antigens was observed. During pegIFN-α/ribavirin therapy, HCV-specific CD4+ and CD8+ T-cells declined similarly in both SVR/RVR and non-SVR/non-RVR patients. Conclusion: No correlation was found between the magnitude of pre-treatment HCV-specific T-cell responses and the outcome of pegIFN-α/ribavirin therapy in terms of SVR and RVR. Moreover, the magnitude of HCV-specific T-cell responses declined in all patients early during treatment.

High level of perforin expression in T cells: An early prognostic marker of the severity of herpesvirus reactivation after allogeneic stem cell transplantation in adults (Article)

2010-03-01T00:00:00Z

Background. Epstein-Barr virus (EBV) and cytomegalovirus reactivations are frequent complications of hematopoeitic allogeneic stem cell transplantation (SCT) because of a lack of T cell control after immunosuppression. Early diagnosis of reactivation and subsequent preemptive therapy relies on frequent viral load measurement. Additional virus-specific T cell reconstitution data could improve the predictive value of viral load detection for viral complications after transplantation. Here, we studied perforin expression in CD8+ T cells as a measure of cytotoxic T cell capacity in relation to the occurrence of viral reactivation. Methods. In a prospective study, we monitored 40 patients during the first 3 months after transplantation and measured viral loads in combination with intracellular perforin expression in CD8+ T cells. Results. Median perforin expression in CD8+ T cells throughout follow-up was higher in patients with viral reactivations than in patients without viral reactivations (4.9% vs 2.3%; P = .001). The median percentage of perforin-expressing CD8+ T cells in patients with high viral reactivations exceeding 1000 copies/mL (10.7%) was statistically significantly higher than that in patients with minor reactivations of 50-1000 copies (4.0%), that in patients with detectable EBV loads that did not exceed the detection limit of 50 copies/mL (2.9%), and that in patients without reactivations (0.8%). Patients with high viral reactivations reached a high percentage of perforinexpressing CD8+ T cells (>10.2%) more often and faster than did patients with low viral loads (≤1000 copies/mL) or without viral reactivations. High perforin expression preceded high viral loads. Conclusion. Perforin-expressing CD8+ T cells may be useful as an easy-to-measure prognostic marker for identifying patients at risk for severe viral reactivation very soon after SCT.

Plasma HCV-RNA decline in the first 48 h identifies hepatitis C virus mono-infected but not HCVHIV-coinfected patients with an undetectable HCV viral load at week 4 of peginterferon-alfa-2aribavirin therapy (Article)

2009-12-01T00:00:00Z

During peginterferon-alfa-2aribavirin therapy, plasma hepatitis C virus (HCV)-RNA decreases with a rapid first phase and a slower second phase. We compared the viral load decrease and slope in the first 48 h in patients with a rapid viral response (RVR, i.e. HCV-RNA < 50 IUmL at week 4) with patients not achieving an RVR. From 23 HCV-infected (14 mono-infected and nine HCVHIV-coinfected) genotype 1 or 4 positive peginterferon-alfa-2aribavirin- treated patients, plasma HCV-RNA was determined at baseline, 48 h, weeks 1, 2, 4, 8, 12, 48 and 72. The HCV viral load decrease (0-48), the slope (λ1) and the efficiency factor (ε) were determined in the first 48 h after the start of therapy. Five (36%) HCV mono-infected patients and three (33%) HIVHCV-coinfected patients achieved an RVR whereas six (43%) HCV mono-infected patients and five (56%) HIVHCV-coinfected patients reached a sustained viral response (SVR). In contrast to HIVHCV-coinfected patients, five HCV mono-infected patients with an RVR showed both a larger 0-48 and steeper1(-1.77log10IUmL ± 0.66 and -2.04day ± 0.76) compared to nine non-RVR patients (-0.66log10IUmL ± 0.39; P = 0.019 and -0.76day ± 0.41; P = 0.019). When divided by SVR, a greater 0-48 and steeper λ1were also seen in both HCV mono-infected and HIVHCV-coinfected patients. Thus, in the first 48 h after the start of therapy, HCV mono-infected patients with an RVR have a larger viral load decrease, steeper viral slope and a higher efficiency factor as compared with non-RVR patients.

Human herpesvirus type 6 reactivation after haematopoietic stem cell transplantation (Article)

2008-12-01T00:00:00Z

Human herpesvirus type 6 (HHV6) is known to reactivate after hematopoetic stem cell transplantation (HSCT) and has been suggested to be associated with increased mortality and severe clinical manifestations, including graft versus host disease (GvHD). The exact etiological role of HHV6 reactivation in increased morbidity and mortality after HSCT remains unclear. This review will focus on the current available evidence of HHV6 reactivation after HSCT and its immuno-modulatory capacities, with particular emphasis on the severe complication GvHD. At present, no effective specific antiviral treatment for HHV6 reactivation has been identified. The currently available antiviral agents are outlined, as well as possible future strategies for the treatment of HHV6 reactivation. Non-toxic, specific treatment or prevention of HHV6 reactivation might improve the safety and efficacy of the HSCT procedure.

Recognition of homo- and heterosubtypic variants of influenza A viruses by human CD8+ T lymphocytes (Article)

2004-01-01T00:00:00Z

In the present study, the recognition of epitope variants of influenza A viruses by human CTL was investigated. To this end, human CD8(+) CTL clones, specific for natural variants of the HLA-B*3501-restricted epitope in the nucleoprotein (NP(418-426)), were generated. As determined in (51)Cr release assays and by flow cytometry with HLA-B*3501-peptide tetrameric complexes, CTL clones were found to be specific for epitopes within one subtype or cross-reactive with heterosubtypic variants of the epitope. Using eight natural variants of the epitope, positions in the 9-mer important for T cell recognition and involved in escape from CTL immunity were identified and visualized using multidimensional scaling. It was shown that positions 4 and 5 in the 9-mer epitope were important determinants of T cell specificity. The in vivo existence of CD8(+) cells cross-reactive with homo- and heterosubtypic variants of the epitope was further confirmed using polyclonal T cell populations obtained after stimulation of PBMC with different influenza A viruses. Based on the observed recognition patterns of the clonal and polyclonal T cell populations and serology, it is hypothesized that consecutive infections with influenza viruses containing different variants of the epitope select for cross-reactive T cells in vivo.

Impaired recovery of Epstein-Barr virus (EBV)--specific CD8+ T lymphocytes after partially T-depleted allogeneic stem cell transplantation may identify patients at very high risk for progressive EBV reactivation and lymphoproliferative disease (Article)

2003-01-01T00:00:00Z

Epstein-Barr virus (EBV)-specific cytotoxic T lymphocytes are considered pivotal to prevent lymphoproliferative disease (LPD) in allogeneic stem cell transplantation (SCT) recipients. We evaluated the recovery of EBV-specific CD8+ T cells after partially T-cell-depleted SCT and studied the interaction between EBV-specific CD8+ T cells, EBV reactivation, and EBV-LPD. EBV-specific CD8+ T cells were enumerated using 12 class I HLA tetramers presenting peptides derived from 7 EBV proteins. Blood samples were taken at regular intervals after SCT in 61 patients, and EBV DNA levels were assessed by real-time polymerase chain reaction. Forty-five patients showed EBV reactivation, including 25 with high-level reactivation (ie, more than 1000 genome equivalents [geq] per milliliter). Nine of these 25 patients progressed to EBV-LPD. CD8+ T cells specific for latent or lytic EBV epitopes repopulated the peripheral blood at largely similar rates. In most patients, EBV-specific CD8+ T-cell counts had returned to normal levels within 6 months after SCT. Concurrently, the incidence of EBV reactivations clearly decreased. Patients with insufficient EBV-specific CD8+ T-cell recovery were at high risk for EBV reactivation in the first 6 months after SCT. Failure to detect EBV-specific CD8+ T cells in patients with high-level reactivation was associated with the subsequent development of EBV-LPD (P =.048). Consequently, the earlier defined positive predictive value of approximately 40%, based on high-level EBV reactivation only, increased to 100% in patients without detectable EBV-specific CD8+ T cells. Thus, impaired recovery of EBV-specific CD8+ T cells in patients with high-level EBV reactivation may identify a subgroup at very high risk for EBV-LPD and supports that EBV-specific CD8+ T cells protect SCT recipients from progressive EBV reactivation and EBV-LPD.

Absolute level of Epstein-Barr Virus (EBV) DNA in human immunodeficiency virus type 1 infection is not predictive of AIDS-related non-Hodgkin lymphoma. (Article)

2002-08-01T00:00:00Z

To study whether Epstein-Barr virus (EBV) load can be used to predict the occurrence of acquired immunodeficiency syndrome-related non-Hodgkin lymphoma (AIDS-NHL), we determined EBV load longitudinally for individuals infected with human immunodeficiency virus type 1. EBV load in peripheral blood mononuclear cells (PBMC) was high and displayed considerable fluctuations over time, indicating that absolute EBV load in PBMC is not predictive of the development of AIDS-NHL. EBV DNA was also detectable in serum at some time points but at a lower level.

Dysfunctional Epstein-Barr virus (EBV)-specific CD8(+) T lymphocytes and increased EBV load in HIV-1 infected individuals progressing to AIDS-related non-Hodgkin lymphoma (Article)

2001-01-01T00:00:00Z

Acquired immunodeficiency syndrome-related non-Hodgkin lymphomas (AIDS-NHL) are thought to arise because of loss of Epstein-Barr Virus (EBV)-specific cellular immunity. Here, an investigation was done to determine whether cellular immunity to EBV is lost because of physical loss or dysfunction of EBV-specific cytotoxic T cells. Data on EBV-specific cellular immunity were correlated with EBV load. For comparison, individuals who progressed to AIDS with opportunistic infections (AIDS-OI) and long-term asymptomatics (LTAs) were studied. The number of virus-specific T cells was detected using tetrameric HLA-EBV-peptide complexes; function of these EBV-specific T cells was determined using the interferon-gamma (IFN-gamma) Elispot assay. It was observed that EBV-specific CD8(+) T cells were present in normal numbers in human immunodeficiency virus (HIV)-infected individuals. However, their functional capacity was decreased compared with HIV(-) individuals. In AIDS-NHL patients, EBV-specific T cells were not physically lost in the course of HIV-1 infection but showed progressive loss of their capability to produce IFN-gamma in response to EBV peptides. This loss of function correlated with lower CD4(+) T-cell numbers and was accompanied by increasing EBV load. In HIV-1-infected LTA individuals, in whom CD4(+) T-cell numbers were maintained, and progressors to AIDS-OI, IFN-gamma-producing EBV-specific T cells were stable and EBV load remained stable or decreased in the course of HIV infection, suggestive of immune control. Our data indicate that functional loss of EBV-specific CD8(+) T cells with a concomitant increase in EBV load may play a role in the pathogenesis of AIDS-NHL.