Patients at high risk for CMV infection and disease show delayed CD8+ T-cell immune recovery after allogeneic stem cell transplantation

Engineered HCMV-infected APCs enable the identification of new immunodominant HLA-restricted epitopes of anti-HCMV T-cell immunity

Complications due to HCMV infection or reactivation remain a challenging clinical problem in immunocompromised patients, mainly due to insufficient or absent T-cell functionality. Knowledge of viral targets is crucial to improve monitoring of high-risk patients and optimise antiviral T-cell therapy. To expand the epitope spectrum, genetically-engineered dendritic cells (DCs) and fibroblasts were designed to secrete soluble (s)HLA-A*11:01 and infected with an HCMV mutant lacking immune evasion molecules (US2-6 + 11). More than 700 HLA-A*11:01-restricted epitopes, including more than 50 epitopes derived from a broad range of HCMV open-reading-frames (ORFs) were identified by mass spectrometry and screened for HLA-A*11:01-binding using established prediction tools. The immunogenicity of the 24 highest scoring new candidates was evaluated in vitro in healthy HLA-A*11:01+/HCMV+ donors. Thus, four subdominant epitopes and one immunodominant epitope, derived from the anti-apoptotic protein UL36 and ORFL101C (A11SAL), were identified. Their HLA-A*11:01 complex stability was verified in vitro. In depth analyses revealed highly proliferative and cytotoxic memory T-cell responses against A11SAL, with T-cell responses comparable to the immunodominant HLA-A*02:01-restricted HCMVpp65NLV epitope. A11SAL-specific T cells were also detectable in vivo in immunosuppressed transplant patients and shown to be effective in an in vitro HCMV-infection model, suggesting their crucial role in inhibiting viral replication and improvement of patient's outcome. The developed in vitro pipeline is the first to utilise genetically-engineered DCs to identify naturally presented immunodominant HCMV-derived epitopes. It therefore offers advantages over in silico predictions, is transferable to other HLA alleles, and will significantly expand the repertoire of viral targets to improve therapeutic options.

Cytomegalovirus Matching in Deceased Donor Kidney Allocation: Results From a U.S. National Simulation Model

Background

Cytomegalovirus (CMV) infects >60% of adults and can pose an independent risk factor for allograft loss and mortality in solid organ transplant recipients. The purpose of this study is to evaluate the impact of a nationwide implementation of CMV seromatching (donor/recipient: D-/R- and D+/R+) in the U.S. deceased donor kidney allocation system (KAS).

Methods

Adult candidates on the U.S. kidney-only transplant waiting list and deceased donor kidneys offered to the U.S. transplant centers were considered. A discrete-event simulation model, simulating the pre-COVID-19 period from January 1, 2015, to January 1, 2018, was used to compare the performances of currently employed KAS-250 policy (without CMV matching) to various simulated CMV matching policies parameterized by calculated panel reactive antibody exception threshold. Outcomes included CMV serodistribution, waiting time, access to transplantation among various groups, transplant rate, graft survival, kidney discard rate, and antigen-mismatch distribution, stratified by CMV serostatus.

Results

CMV matching policy with a calculated panel reactive antibody exception threshold of 50% (namely, the CMV">50%" policy) strikes a better balance between benefits and drawbacks of CMV matching. Compared with KAS-250, CMV">50%" reduced CMV high-risk (D+/R-) transplants (6.1% versus 18.1%) and increased CMV low-risk (D-/R-) transplants (27.2% versus 13.1%); increased transplant rate for CMV R- patients (11.54 versus 12.57) but decreased for R+ patients (10.68 versus 10.48), yielding an increase in aggregate (11.09 versus 10.94); and reduced mean time to transplantation (by 6 wk); and reduced kidney discard rate (25.7% versus 26.2%).

Conclusions

Our findings underscore the feasibility and potential advantages of a nationwide CMV seromatching policy in kidney transplantation.

Secretion of IFN-γ by specific T cells in HCMV infection

One major risk for recipients undergoing allogeneic hematopoietic stem cell transplants (allo-HSCTs) is infection with the human cytomegalovirus (HCMV). For HCMV treatment, it is especially crucial to be able to differentiate between recipients who are at high risk of reactivation and those who are not. In this study, HCMV-DNA was collected from 60 HLA-A*02 allo-HSCT recipients before and after transplantation. After transplantation, the release of interferon (IFN)-γ by T cells specific to HCMV was assessed using the enzyme-linked immunospot assay (ELISPOT). The results show that the median viral load (VL) was significantly higher in the HCMV persistent-infection group compared to the non-persistent-infection group (p = 0.002), and that the late-infection rate was considerably higher in the high-VL group compared to the low-VL group (p = 0.014). The uninfected group had a considerably higher median IFN-γ spot-forming cell (SFC) count than the persistent-infection group (p = 0.001), and IFN-γ SFC counts correlated negatively and linearly with VLs (r = -0.397, p = 0.002). The immune-response groups showed significantly difference in median VL (p = 0.018), and the high immune response group had a reduced late-infection rate than the no/low immune response groups (p = 0.049). Our study showed that allo-HSCT recipients with a high VL at an early transplantation stage were at high risk for late HCMV infection. Further HCMV reactivation can be prevented by HCMV-specific T cells secreting enough IFN-γ.

Clinical and healthcare burden of disease associated with cytomegalovirus in allogeneic hematopoietic stem cell transplantation - A retrospective single-center study

BACKGROUND

CMV infection is a common complication in allogeneic hematopoietic stem cell transplantation (HSCT). We investigated the association of clinically significant CMV (CS-CMV) infection with clinical outcomes and healthcare resource utilization in allogeneic HSCT patients in Finland.

METHODS

This retrospective study included adult patients who received their first allogeneic HSCT between January 1, 2013, and December 31, 2018, at the Turku University Hospital. Data were collected from the hospital data lake. Clinical and healthcare outcomes were investigated at one year and mortality up to three years.

RESULTS

The study included 251 patients. CMV seroprevalence was 69.7%. CS-CMV infection occurred in 59.0% of the patients, and of those, 14.2% had ≥2 infections. The median time to CS-CMV infection was 34.5 days (Q₁ -Q₃ , 27.0-45.0). Recipient and donor seropositivity, and lymphoproliferative diseases were associated with higher, and HLA identical sibling donors with lower CS-CMV infection risk. CS-CMV infection was not associated with mortality in three years of follow-up. One hundred thirty-three (89.8%) and 75 (72.8%) patients with and without CS-CMV infection, respectively, were readmitted to the hospital. Patients with CS-CMV infection had more hospital readmissions (incidence rate ratio [IRR] 1.38, 95% confidence interval [CI] 1.10-1.73, p = .005) and patients with one CS-CMV infection (IRR 1.48, 95% CI 1.12-1.94, p = .005) or ≥2 infections had longer length of hospital stay (IRR 2.71, 95% CI 1.76-4.35, p < .001).

CONCLUSION

CMV seroprevalence is relatively high among Finnish allogeneic HSCT patients. CS-CMV infection was common and associated with a higher readmission rate and longer length of hospital stay.

Efficacy of pp65-specific TCR-T cell therapy in treating cytomegalovirus infection after hematopoietic stem cell transplantation

Cytomegalovirus (CMV) infection remains a major cause of mortality after hematopoietic stem cell transplantation (HSCT). Current treatments, including antiviral drugs and adoptive cell therapy with CMV-specific cytotoxic T lymphocytes (CTLs), only show limited benefits in patients. T-cell receptor (TCR)-T cell therapy offers a promising option to treat CMV infections. Here, using tetramer-based screening and single-cell TCR cloning technologies, we identified various CMV antigen-specific TCRs from healthy donors, and generated TCR-T cells targeting multiple pp65 epitopes corresponding to three major HLA-A alleles. The TCR-T cells showed efficient cytotoxicity toward epitope-expressing target cells in vitro. After transfer into immune-deficient mice bearing pp65⁺ HLA⁺ tumor cells, TCR-T cells induced dramatic tumor regression and exhibited long-term persistence. In a phase I clinical trial (NCT04153279), CMV TCR-T cells were applied to treat patients with CMV reactivation after HSCT. Except one patient who withdrew at early treatment stage, all other six patients were well-tolerated and achieved complete response (CR), no more than grade 2 cytokine release syndrome (CRS) and other adverse events were observed. CMV TCR-T cells persisted up to 3 months. Among them, two patients have survived for more than 1 year. This study demonstrates the great potential in the treatment and prevention of CMV infection following HSCT or other organ transplantation.

Features of cytomegalovirus infection and evaluation of cytomegalovirus-specific T cells therapy in children’s patients following allogeneic hematopoietic stem cell transplantation: A retrospective single-center study

Cytomegalovirus (CMV) infection remains a critical cause of mortality after allogeneic hematopoietic stem cell transplantation (allo-HSCT), despite improvement by pre-emptive antivirus treatment. CMV-specific cytotoxic T lymphocytes (CMV-CTL) are universally used and proven well-tolerance after allo-HSCT in adult clinical trials. However, it is not comprehensively evaluated in children’s patients. Herein, we conducted a retrospective study to determine the risk factors of CMV infection and evaluation of CMV-CTL in children patients who underwent allo-HSCT. As result, a significantly poor 5-year overall survival was found in the CMV infection group (87.3 vs. 94.6%, p=0.01). Haploidentical HSCT (haplo-HSCT) was identified as an independent risk factor for CMV infection through both univariate and multivariate analyses (p<0.001, p=0.027, respectively). Furthermore, the cumulative incidence of CMV infection was statistically higher in the haplo-HSCT group compared to the HLA-matched donor group (44.2% vs. 21.6%, p<0.001). Finally, the overall response rate of CMV-CTL was 89.7% (26/29 patients) in CMV infection after allo-HSCT. We concluded that CMV infection following allo-HSCT correlated with increased mortality in children’s patients, and haplo-HSCT was an independent risk factor for CMV infection. Adoptive CMV-CTL cell therapy was safe and effective in pediatric patients with CMV infection.

Diagnosis and treatment for the early stage of cytomegalovirus infection during hematopoietic stem cell transplantation

Cytomegalovirus (CMV) infection remains a frequent complication after hematopoietic stem cell transplantation (HSCT) and causes significant morbidity and mortality in transplantation recipients. In this review, we highlight the role of major risk factors that are associated with the incidence of CMV infection. Advances in immunosurveillance may predict CMV infection, allowing early interventions to prevent severe infection. Furthermore, numerous therapeutic strategies against CMV infection after HSCT are summarized. A comprehensive understanding of the current situation of CMV treatment may provide a hint for clinical practice and even promote the development of novel strategies for precision medicine.

Prevention and management of human cytomegalovirus in pediatric HSCT recipients: A review

Cytomegalovirus (CMV), like other herpesviruses, has the unique ability to establish latent infection with subsequent reactivation during periods of stress and immunosuppression. Herpesviruses cause potentially devastating disease, particularly in hematopoietic stem cell transplant (HSCT) recipients. CMV is especially of concern in HSCT recipients given the high community seroprevalence, high risk of reactivation and high risk of transmission from HSCT donors to recipients causing primary infection after transplantation. The risk of CMV infection and severity of CMV disease varies depending on the underlying disease of the HSCT recipient, donor and recipient CMV status prior to HSCT, type of conditioning therapy in preparation for HSCT, allogeneic versus autologous HSCT, donor graft source, timing of infection in relation to HSCT, and other patient comorbidities. Different strategies exist for prevention (e.g., preemptive therapy vs. universal prophylaxis) as well as management of CMV disease (e.g., antiviral therapy, augmenting immune reconstitution, cytotoxic T-cell therapy). The purpose of this narrative review is to discuss diagnosis, prevention, and management of CMV infection and disease at different stages of HSCT, including key points illustrated through presentations of complex cases and difficult clinical scenarios. Traditional and novel strategies for CMV management will be discussed in the context of these unique clinical cases.

Post-HSCT graft failure due to refractory human cytomegalovirus successfully treated with haploidentical donor-derived immunoglobulins and stem cell graft infusion: A case report

Background

Human cytomegalovirus (HCMV) remains an important cause of transplant-related morbidity and mortality. The incidence of HCMV recurrence in the donor seronegative (D-)/recipient seropositive (R+) group is significantly higher than in other serostatus combinations as a result of a lack of pre-existing HCMV-specific memory T-lymphocytes in the donor, coupled with the eradication of the recipient's cellular immunity due to the conditioning regimen.

Case presentation

We describe the case of an 8-year-old βE-thalassemic girl from Bangladesh who was seropositive for human cytomegalovirus (HCMV) and underwent hematopoietic stem cell transplantation from a HLA-matched, unrelated, HCMV-seronegative donor. Despite administering antiviral prophylaxis with commercial pooled anti-HCMV immunoglobulin (Ig) from day +1, the post-transplant course was complicated by prompt viral reactivation, and foscarnet therapy was initiated. The virus was refractory to treatment, leading rapidly to complete bone marrow failure, and targeted immunotherapy was proposed as a second-line therapy. Hypothesizing that the patient and her relatives may have been exposed to similar HCMV strains, we selected the patient's mother, who presented a high HCMV antibody titer, as the donor of virus strain-specific anti-HCMV Ig and T-lymphocytes. Complete viral clearance was achieved after two transfusions of the mother's plasma. Subsequently, the patient underwent a haploidentical rescue transplant, promptly reaching full hematological recovery.

Conclusion

These findings suggest that treatment with virus strain-specific Ig may offer a new therapeutic option for critically ill patients.

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Human cytomegalovirus (HCMV) remains an important cause of transplant-related morbidity and mortality.

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Reactivation of multiple viral strains is particularly challenging to eradicate. .

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Virus strain-specific Ig is an inexpensive, non-toxic therapy to treat HCMV reactivation and improve transplant outcomes. .

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The efficacy of this approach as a means of prevention has only been demonstrated previously in mouse models.

Recent Approaches and Strategies in the Generation of Anti-human Cytomegalovirus Vaccines

Human cytomegalovirus is the largest human herpesvirus and shares many core features of other herpesviruses such as tightly regulated gene expression during genome replication and latency as well as the establishment of lifelong persistence following infection. In contrast to stereotypic clinical syndromes associated with alpha-herpesvirus infections, almost all primary HCMV infections are asymptomatic and acquired early in life in most populations in the world. Although asymptomatic in most individuals, HCMV is a major cause of disease in hosts with deficits in adaptive and innate immunity such as infants who are infected in utero and allograft recipients following transplantation. Congenital HCMV is a commonly acquired infection in the developing fetus that can result in a number of neurodevelopmental abnormalities. Similarly, HCMV is a major cause of disease in allograft recipients in the immediate and late posttransplant period and is thought to be a major contributor to chronic allograft rejection. Even though HCMV induces robust innate and adaptive immune responses, it also encodes a vast array of immune evasion functions that are thought aid in its persistence. Immune correlates of protective immunity that prevent or modify intrauterine HCMV infection remain incompletely defined but are thought to consist primarily of adaptive responses in the pregnant mother, thus making congenital HCMV a potentially vaccine modifiable disease. Similarly, HCMV infection in allograft recipients is often more severe in recipients without preexisting adaptive immunity to HCMV. Thus, there has been a considerable effort to modify HCMV specific immunity in transplant recipient either through active immunization or passive transfer of adaptive effector functions. Although efforts to develop an efficacious vaccine and/or passive immunotherapy to limit HCMV disease have been underway for nearly six decades, most have met with limited success at best. In contrast to previous efforts, current HCMV vaccine development has relied on observations of unique properties of HCMV in hopes of reproducing immune responses that at a minimum will be similar to that following natural infection. However, more recent findings have suggested that immunity following naturally acquired HCMV infection may have limited protective activity and almost certainly, is not sterilizing. Such observations suggest that either the induction of natural immunity must be specifically tailored to generate protective activity or alternatively, that providing targeted passive immunity to susceptible populations could be prove to be more efficacious.

Unknown cytomegalovirus serostatus in primary immunodeficiency disorders: A new category of transplant recipients

BACKGROUND

Cytomegalovirus (CMV) serostatus of recipient (R) and donor (D) influences hematopoietic stem cell transplant (HSCT) outcome. However, it is not a reliable indicator of CMV infection in primary immunodeficiency disorder (PIDD) recipients who are unable to make adequate antigen-specific immunoglobulin (Ig) or who receive intravenous Ig (IVIg) prior to testing.

OBJECTIVE

Since no data exist on PIDD with unknown CMV serostatus, we aimed to evaluate the relationship between pre-HSCT recipient and donor serostatus and incidence of CMV infection in recipients with unknown serostatus.

METHODS

A retrospective analysis of all pediatric PIDD HSCTs (2007-2018) was performed at University of California San Francisco. Recipients were separated into categories based on pre-transplant serostatus: 1) seropositive (R(+)), 2) seronegative (R(-)), and 3) unknown serostatus (R(x)). Patients with pre-HSCT active CMV viremia were excluded.

RESULTS

A total of 90 patients were included, 69% male. The overall incidence of CMV infection was 20%, but varied in R(+), R(-), and R(x) at 80%, 0%, and 14%, (P-value = .0001). Similarly, 5-year survival differed among groups, 60% R(+), 100% R(-), and 90% of R(x) (P-value = .0045). There was no difference in CMV reactivation by donor serostatus (P-value = .29), however, faster time to clearance of CMV was observed for R(x)/D(+) group (median 9.5 days (IQR 2.5-18), P-value = .024).

CONCLUSION

We identify a novel group of recipients, R(x), with an intermediate level of survival and CMV incidence post-HSCT, when compared to seropositive and seronegative recipients. No evidence of CMV transmission from D(+) in R(-) and R(x) was observed. We believe R(x) should be considered as a separate category in future studies to better delineate recipient risk status.

Guidelines for the management of cytomegalovirus infection in patients with haematological malignancies and after stem cell transplantation from the 2017 European Conference on Infections in Leukaemia (ECIL 7)

Cytomegalovirus is one of the most important infections to occur after allogeneic haematopoietic stem cell transplantation (HSCT), and an increasing number of reports indicate that cytomegalovirus is also a potentially important pathogen in patients treated with recently introduced drugs for hematological malignancies. Expert recommendations have been produced by the 2017 European Conference on Infections in Leukaemia (ECIL 7) after a review of the literature on the diagnosis and management of cytomegalovirus in patients after HSCT and in patients receiving other types of therapy for haematological malignancies. These recommendations cover diagnosis, preventive strategies such as prophylaxis and pre-emptive therapy, and management of cytomegalovirus disease. Antiviral drugs including maribavir and letermovir are in development and prospective clinical trials have recently been completed. However, management of patients with resistant or refractory cytomegalovirus infection or cytomegalovirus disease is a challenge. In this Review we summarise the reviewed literature and the recommendations of the ECIL 7 for management of cytomegalovirus in patients with haematological malignancies.

Human Cytomegalovirus Latency and Reactivation in Allogeneic Hematopoietic Stem Cell Transplant Recipients

Human cytomegalovirus (HCMV) reactivation is a major infectious cause of morbidity and mortality after allogeneic hematopoietic stem cell transplantation (HSCT). HCMV is a ubiquitous beta-herpesvirus which asymptomatically infects immunocompetent individuals but establishes lifelong latency, with the potential to reactivate to a life-threatening productive infection when the host immune system is suppressed or compromised. Opportunistic HCMV reactivation is the most common viral complication following engraftment after HSCT and is associated with a marked increase in non-relapse mortality, which appears to be linked to complex effects on post-transplant immune recovery. This minireview explores the cellular sites of HCMV latency and reactivation in HSCT recipients and provides an overview of the risk factors for HCMV reactivation post-HSCT. The impact of HCMV in shaping post-transplant immune reconstitution and its relationship with patient outcomes such as relapse and graft-versus-host disease will be discussed. Finally, we survey current and emerging strategies to prevent and control HCMV reactivation in HSCT recipients, with recent developments including adoptive T cell therapies to accelerate HCMV-specific T cell reconstitution and new anti-HCMV drug therapy for HCMV reactivation after HSCT.

The prognostic impact of the cytomegalovirus serostatus in patients with chronic hematological malignancies after allogeneic hematopoietic stem cell transplantation: a report from the Infectious Diseases Working Party of EBMT

It has been shown recently that donor and/or recipient cytomegalovirus (CMV) seropositivity is associated with a significant overall survival (OS) decline in acute leukemia patients who underwent allogeneic hematopoietic stem cell transplantation (allo-HSCT). We now analyzed the prognostic impact of the donor/recipient CMV serostatus in 6968 patients with chronic hematological malignancies who underwent allo-HSCT. Donor and/or recipient CMV seropositivity was associated with a significantly reduced 2-year progression-free survival (PFS, 50% vs. 52%, p = 0.03) and OS (62% vs. 65%, p = 0.01). Multivariate Cox regression analyses showed an independent negative prognostic impact of donor and/or recipient CMV seropositivity on PFS (HR, 1.1; 95% CI, 1.0-1.2; p = 0.03), OS (HR, 1.1; 95% CI, 1.0-1.2; p = 0.003), and non-relapse mortality (HR, 1.2; 95% CI, 1.0-1.3; p = 0.02). OS decline was strongest for CMV-seropositive recipients with a CMV-seronegative donor (HR, 1.2; 95% CI, 1.1-1.3), followed by CMV-seropositive patients with a CMV-seropositive donor (HR, 1.1; 95% CI, 1.0-1.2). Conversely, OS did not differ significantly between CMV-seronegative recipients allografted from a CMV-seropositive donor (HR, 1.0; 95% CI, 0.9-1.2) and patients with donor/recipient CMV seronegativity (p = 0.001 for the four groups together). Non-relapse mortality was also significantly (p = 0.01) higher for CMV-seropositive patients with a CMV-seronegative graft (HR, 1.2; 95% CI, 1.1-1.4) than for CMV-seropositive patients with a CMV-seropositive graft (HR, 1.1; 95% CI, 0.9-1.2) or CMV-seronegative recipients with a CMV-seropositive graft (HR, 1.0; 95% CI, 0.8-1.2). Donor and/or recipient CMV seropositivity still results in an OS decline in patients with chronic hematological malignancies who have undergone allo-HSCT. However, this OS decline seems to be lower than that described for acute leukemia patients previously.

Maternal Immunity and the Natural History of Congenital Human Cytomegalovirus Infection

Congenital human cytomegalovirus (HCMV) is the most common viral infection of the developing fetus, and a significant cause of neurodevelopmental abnormalities in infants and children. Congenital HCMV infections account for an estimated 25% of all cases of hearing loss in the US. It has long been argued that maternal adaptive immune responses to HCMV can modify both the likelihood of intrauterine transmission of HCMV, and the severity of fetal infection and risk of long term sequelae in infected infants. Over the last two decades, multiple studies have challenged this paradigm, including findings that have demonstrated that the vast majority of infants with congenital HCMV infections in most populations are born to women with established immunity prior to conception. Furthermore, the incidence of clinically apparent congenital HCMV infection in infants born to immune and non-immune pregnant women appears to be similar. These findings from natural history studies have important implications for the design, development, and testing of prophylactic vaccines and biologics for this perinatal infection. This brief overview will provide a discussion of existing data from human natural history studies and animal models of congenital HCMV infections that have described the role of maternal immunity in the natural history of this perinatal infection.

Assessing the risk of CMV reactivation and reconstitution of antiviral immune response post bone marrow transplantation by the QuantiFERON-CMV-assay and real time PCR

BACKGROUND

CMV reactivation is a major cause of severe complications in allogeneic hematopoietic stem cell transplant (HSCT) recipients. The risk of CMV reactivation depends on the serostatus (+/-) of the donor (D) and recipient (R). The reconstitution of CMV-specific T-cell responses after transplantation is crucial for the control of CMV reactivation.

OBJECTIVES

The study aimed to determine the cellular immune status correlating with protection from high-level CMV viremia (>5000 copies/ml) and disease.

STUDY DESIGN

We monitored CMV-specific cellular immune responses in 9 high-risk (D-/R+), 14 intermediate risk (D+/R+) and 3 low risk individuals (D+/R-), and 8 CMV negative controls (D-/R-). Interferon- γ (IFN-γ) levels as a marker for the CD8+ T-cell response were determined by the QuantiFERON-CMV-assay and compared to viral loads determined by PCR.

RESULTS

Early CMV reactivation was detected in all high-risk and 13/14 intermediate risk individuals. High-level viremia was detected in 5/7 high and 7/14 intermediate risk patients. Reconstitution of the CMV-specific cellular immune response started from 3 months after transplantation and resulted in protection against CMV reactivation. Re-establishing of CMV-specific T-cell immune responses with IFN- γ levels >8.9 IU/ml is crucial for protection from high-level CMV viremia.

CONCLUSIONS

Monitoring of HSCT-recipients with the QuantiFERON-CMV-assay might be of great benefit to optimize antiviral treatment.

Who Is the Patient at Risk of CMV Recurrence: A Review of the Current Scientific Evidence with a Focus on Hematopoietic Cell Transplantation

Cytomegalovirus (CMV) is an agent of global infection, and its acquisition in a population is characterized by an age-dependent rise in seropositivity. After primary infection, CMV remains in the host cells in latent form, and it can reactivate in the case of immune suppression. The risk of CMV recurrence is dependent on the level of incompetency of the immune system, manifested as an impairment of T-cell immunity, including the presence and function of CMV-specific cytotoxic T lymphocytes. This article presents data on the incidence of CMV recurrence in groups of immunocompromised patients, including allogeneic hematopoietic stem cell transplantation (HSCT) patients and other groups of patients, based on a summary of reported data. The median rate of CMV recurrence in HSCT recipients was estimated as 37% after allogeneic transplant and 12% after autologous transplant, 5% in patients with nontransplant hematological malignancies, 14% in recipients of anti-CD52 therapy, 30% in solid organ transplant recipients, 21% in patients with primary immunodeficiencies, 20% during active replication in HIV-positive patients and 3.3% during antiretroviral therapy, 7% in patients with chronic kidney disease, 0.6% in patients with congenital infection, and 0.6% in neonates with primary infection. The highest risk of CMV recurrence and CMV disease is reported for HSCT CMV-seropositive recipients, regardless of donor serostatus. The odds ratio (OR) for CMV recurrence is higher for recipient-positive versus recipient-negative CMV serostatus transplants (OR 8.0), donor-negative/recipient-positive versus donor-positive/recipient-positive CMV serostatus transplants (OR 1.2), unrelated/mismatched versus matched-family donor transplants (OR 1.6), and acute graft-versus-host-disease versus other diseases (OR 3.2). Other risk factors have minor significance.

Long-term control of recurrent or refractory viral infections after allogeneic HSCT with third-party virus-specific T cells

Donor-derived adoptive T-cell therapy is a safe and effective treatment of viral infection posttransplant, but it is limited by donor serostatus and availability and by its personalized nature. Off-the-shelf, third-party virus-specific T cells (VSTs) appear promising, but the long-term safety and durability of responses have yet to be established. We conducted a prospective study of 30 allogeneic hemopoietic stem cell transplant (HSCT) patients with persistent or recurrent cytomegalovirus (CMV) (n = 28), Epstein-Barr virus (n = 1), or adenovirus (n = 1) after standard therapy. Patients were treated with infusions of partially HLA-matched, third-party, ex vivo-expanded VSTs (total = 50 infusions) at a median of 75 days post-HSCT (range, 37 to 349 days). Safety, viral dynamics, and immune recovery were monitored for 12 months. Infusions were safe and well tolerated. Acute graft versus host disease occurred in 2 patients, despite a median HLA match between VSTs and the recipient of 2 of 6 antigens. At 12 months, the cumulative incidence of overall response was 93%. Virological control was durable in the majority of patients; the reintroduction of antiviral therapy after the final infusion occurred in 5 patients. CMV-specific T-cell immunity rose significantly and coincided with a rise in CD8⁺ terminal effector cells. PD-1 expression was elevated on CD8⁺ lymphocytes before the administration of third-party T cells and remained elevated at the time of viral control. Third-party VSTs show prolonged benefit, with virological control achieved in association with the recovery of CD8⁺ effector T cells possibly facilitated by VST infusion. This trial was registered at www.clinicaltrials.gov as #NCT02779439 and www.anzctr.org.au as #ACTRN12613000603718.

Identifying Cytomegalovirus Complications Using the Quantiferon-CMV Assay After Allogeneic Hematopoietic Stem Cell Transplantation

Background

A simple test to identify recovery of CMV-specific T-cell immunity following hematopoietic stem cell transplantation (HSCT) could assist clinicians in managing CMV-related complications.

Methods

In an observational, multicenter, prospective study of 94 HSCT recipients we evaluated CMV-specific T-cell immunity at baseline, 3, 6, 9, and 12 months after transplant using the Quantiferon-CMV, an enzyme-linked immunosorbent spot assay (ELISpot), and intracellular cytokine staining.

Results

At 3 months after HSCT, participants who developed CMV disease (n = 8) compared with CMV reactivation (n = 26) or spontaneous viral control (n = 25) had significantly lower CD8+ T-cell production of interferon-γ (IFN-γ) in response to CMV antigens measured by Quantiferon-CMV (P = .0008). An indeterminate Quantiferon-CMV result had a positive predictive value of 83% and a negative predictive value of 98% for identifying participants at risk of further CMV reactivation. Participants experiencing CMV reactivation compared with patients without CMV reactivation had a reduced proportion of polyfunctional (IFN-γ+/tumor necrosis factor α-positive) CD4+ and CD8+ T cells and a higher proportion of interleukin 2-secreting cells (P = .01 and P = .002, respectively).

Conclusions

Quantifying CMV-specific T-cell immunity after HSCT can identify participants at increased risk of clinically relevant CMV-related outcomes.

CMV-specific immune reconstitution following allogeneic stem cell transplantation

Cytomegalovirus (CMV) remains a major contributor to morbidity and mortality following allogeneic haemopoietic stem cell transplant (HSCT) despite widespread use of viraemia monitoring and pre-emptive antiviral therapy. Uncontrolled viral replication occurs primarily in the first 100 d post transplant but this high risk period can extend to many months if immune recovery is delayed. The re-establishment of a functional population of cellular effectors is essential for control of virus replication and depends on recipient and donor serostatus, the stem cell source, degree of HLA matching and post-transplant factors such as CMV antigen exposure, presence of GVHD and ongoing use of immune suppression. A number of immune monitoring assays exist but have not yet become widely accessible for routine clinical use. Vaccination, adoptive transfer of CMV specific T cells and a number of graft engineering processes are being evaluated to enhance of CMV specific immune recovery post HSCT.

Rapid reconstitution of CD4 T cells and NK cells protects against CMV-reactivation after allogeneic stem cell transplantation

BACKGROUND

Epstein-Barr virus and Cytomegalovirus reactivations frequently occur after allogeneic stem cell transplantation (SCT).

METHODS

Here we investigated the role of immune cell reconstitution in the onset and subsequent severity of EBV- and CMV-reactivation. To this end, 116 patients were prospectively sampled for absolute T cell (CD4 and CD8), B-cell (CD19) and NK-cell (CD16 and CD56) numbers weekly post-SCT during the first 3 months and thereafter monthly until 6 months post-SCT. Viral load was monitored in parallel.

RESULTS

In contrast to the general belief, we found that early T-cell reconstitution does not play a role in the onset of viral reactivation. CMV reactivation in the first 7 weeks after SCT however resulted in higher absolute CD8(+) T-cell numbers 6 months post-SCT in patients with high-level reactivation, many of which were CMV-specific. Interestingly, rapid reconstitution of CD4(+) T-cells, as well as NK cells and the presence of donor KIR3DL1, are associated with the absence of CMV-reactivation after SCT, suggestive of a protective role of these cells. In contrast, EBV-reactivations were not affected in any way by the level of immune reconstitution after SCT.

CONCLUSION

In conclusion, these data suggest that CD4(+) T-cells and NK cells, rather than CD8(+) T-cells, are associated with protection against CMV-reactivation.

Immunotherapy for opportunistic infections: Current status and future perspectives

The outcome after allogeneic haematopoietic stem cell transplantation (allo-HSCT) has significantly improved during the last decades. However, opportunistic infections such as viral and mold infections are still a major obstacle for cure. Within this field, adoptive T cell therapy against pathogens is a promising treatment approach. Recently, the techniques to develop T cell products including pathogen-specific T cells have been sophisticated and are now available in accordance to good manufacturing practice (GMP). Here, we aim to summarize current knowledge about adoptive T cell therapy against viral and mold infections.

Cytomegalovirus-specific T-cell therapies: current status and future prospects

Adoptive transfer of T cells specific for viral pathogens offers an attractive method for hastening immune reconstitution and protective immunity in patients following stem cell transplantation. The largest experience to date has been in the context of treatment or prevention of cytomegalovirus or Epstein-Barr virus. A number of technical hurdles have now been overcome allowing consideration of more widespread application of products compliant with Good Manufacturing Practice regulations, and of the development of commercialization pathways for these products. This review summarizes progress to date and highlights some of the areas that remain problematic and that require further innovation and evaluation before more widespread adoption is considered.

Low Counts of B Cells, Natural Killer Cells, Monocytes, Dendritic Cells, Basophils, and Eosinophils are Associated with Postengraftment Infections after Allogeneic Hematopoietic Cell Transplantation

Hematopoietic cell transplant (HCT) recipients are immunocompromised and thus predisposed to infections. We set out to determine the deficiency of which immune cell subset(s) may predispose to postengraftment infections. We determined day 28, 56, 84, and 180 blood counts of multiple immune cell subsets in 219 allogeneic transplant recipients conditioned with busulfan, fludarabine, and Thymoglobulin. Deficiency of a subset was considered to be associated with infections if the low subset count was significantly associated with subsequent high infection rate per multivariate analysis in both discovery and validation cohorts. Low counts of monocytes (total and inflammatory) and basophils, and low IgA levels were associated with viral infections. Low plasmacytoid dendritic cell (PDC) counts were associated with bacterial infections. Low inflammatory monocyte counts were associated with fungal infections. Low counts of total and naive B cells, total and CD56(high) natural killer (NK) cells, total and inflammatory monocytes, myeloid dendritic cells (MDCs), PDCs, basophils and eosinophils, and low levels of IgA were associated with any infections (due to any pathogen or presumed). In conclusion, deficiencies of B cells, NK cells, monocytes, MDCs, PDCs, basophils, eosinophils, and/or IgA plasma cells appear to predispose to postengraftment infections.

Sequential therapy combining clofarabine and T-cell-replete HLA-haploidentical haematopoietic SCT is feasible and shows efficacy in the treatment of refractory or relapsed aggressive lymphoma

Prognosis is poor for patients with biologically aggressive Non-Hodgkin lymphoma (NHL), refractory to chemotherapy or relapsed after autologous transplantation, especially when no disease control before allogeneic transplantation is achieved. In 16 patients (median age 53, median prior regimes 5) with relapsed or refractory non-remission NHL, we analysed retrospectively the efficacy of a sequential therapy comprising clofarabine re-induction followed by a reduced-intensity conditioning with fludarabine, CY and melphalan, and T-cell-replete HLA-haploidentical transplantation. High-dose CY was utilized post-transplantation. All patients engrafted. Early response (day +30) was achieved in 94%. Treatment-related grade III-IV toxicity occurred in 56%, most commonly transient elevation of transaminases (36%), while there was a low incidence of infections (19% CMV reactivation, 19% invasive fungal infection) and GVHD (GVHD: acute III-IV: 6%; mild chronic: 25%). One-year non-relapse mortality was 19%. After a median follow-up of 21 months, estimated 1- and 2-year PFS was 56 and 50%, respectively, with 11 patients (69%) still alive after 2 years. In summary, sequential therapy is feasible and effective and provides an acceptable toxicity profile in high-risk non-remission NHL. Presumably, cytotoxic reinduction with clofarabine provides enough remission time for the graft-versus lymphoma effect of HLA-haploidentical transplantation to kick in, even in lymphomas that are otherwise chemo-refractory.

An update on the management and prevention of cytomegalovirus infection following allogeneic hematopoietic stem cell transplantation

ABSTRACT 

A significant progress has been made in deciphering critical aspects of the biology and immunology of CMV infection in the allogeneic stem cell transplantation setting. Genetic traits predisposing to active CMV infection and CMV end-organ disease have begun to be delineated. Reliable molecular assays for CMV DNA load quantitation in body fluids have been developed. Elucidation of immune mechanisms affording control of CMV infection will help to improve the management of active CMV infection. Finally, the advent of new CMV-specific antivirals and promising vaccine prototypes as well as the development of fine procedures for large-scale ex vivo generation of functional CMV-specific T cells for adoptive T cell transfer therapies will certainly minimize the negative impact of CMV on survival in these patients.

Donor cytomegalovirus status influences the outcome of allogeneic stem cell transplant: a study by the European group for blood and marrow transplantation

BACKGROUND

The use of a cytomegalovirus (CMV)-seronegative donor for a CMV-seronegative allogeneic hematopoietic stem cell transplant (HSCT) recipient is generally accepted. However, the importance of donor serostatus in CMV-seropositive patients is controversial.

METHODS

A total of 49 542 HSCT patients, 29 349 seropositive and 20 193 seronegative, were identified from the European Group for Blood and Marrow Transplantation database. Cox multivariate models were fitted to estimate the effect of donor CMV serological status on outcome.

RESULTS

Seronegative patients receiving seropositive unrelated-donor grafts had decreased overall survival (hazard ratio [HR], 1.13; 95% confidence interval [CI], 1.06-1.21; P < .0001) compared with seronegative donors, whereas no difference was seen in patients receiving HLA-matched sibling grafts. Seropositive patients receiving grafts from seropositive unrelated donors had improved overall survival (HR, 0.92; 95% CI, .86-.98; P < .01) compared with seronegative donors, if they had received myeloablative conditioning. This effect was absent when they received reduced-intensity conditioning. No effect was seen in patients grafted from HLA-identical sibling donors. The same association was found if the study was limited to patients receiving transplants from the year 2000 onward.

CONCLUSIONS

We confirm the negative impact on overall survival if a CMV-seropositive unrelated donor is selected for a CMV-seronegative patient. For a CMV-seropositive patient, our data support selecting a CMV-seropositive donor if the patient receives a myeloablative conditioning regimen.

T-cell therapy for cytomegalovirus infection

PURPOSE OF REVIEW

Human cytomegalovirus (CMV) reactivation and disease remains one of the major complications after allogeneic haemopoietic stem cell transplantation. Cell-mediated immunity is essential in counteracting CMV infection as evident by detection of high frequencies of CMV-specific CD8 and CD4 lymphocytes among the healthy CMV-seropositive individuals. Adoptive transfer of CMV-specific T cells to speed up reconstitution of CMV-specific immunity potentially offers clinical protection and reduces drug toxicities as well as outgrowth of drug-resistant strains from prolonged antiviral therapy.

RECENT FINDINGS

Different strategies to generate CMV-specific T cell have been explored. Similarly, vast diversities in term of cell dose and composition of the cellular product have been infused into small cohorts of patients. To date, a number of phase I/II clinical trials have demonstrated the feasibility of adoptive transferred CMV-specific T cells as prophylaxis, pre-emptive or therapeutic measure. In general, all these strategies showed variable degrees of efficacy without obvious adverse event particularly with regard to the induction of graft-versus-host disease.

SUMMARY

In this review, we would like to give a comprehensive synopsis regarding therapeutic application of CMV-specific T cells in fighting CMV infection.

Lower proportion of naïve peripheral CD8+ T cells and an unopposed pro-inflammatory response to human Cytomegalovirus proteins in vitro are associated with longer survival in very elderly people

The low percentages of naïve T cells commonly observed in elderly people are thought to be causally associated with mortality, primarily from infectious disease, and are taken as a hallmark of "immunosenescence". Whether low levels of naive cells actually do associate with mortality has, however, not been tested in longitudinal studies. Here, we present correlations between peripheral T-cell phenotypes and 8-year survival in individuals from the population-based prospective Leiden 85-plus Study. Counter-intuitively, we found that a lower frequency of naïve CD8+ T cells (characterized as CD45RA+CCR7+CD27+CD28+) at baseline (>88 years) correlated with significantly better survival, while there was a tendency for the reciprocal accumulation of late-differentiated effector memory cells (CD45RA-CCR7-CD27-CD28-) also to associate with better survival. These findings suggest that better retention of memory cells specific for previously encountered antigens may provide a survival advantage in this particular population. Given the prevalence of Cytomegalovirus (CMV) and its reported association with immunosenescence, we tested whether memory for this potential pathogen was relevant to survival. We found that individuals mounting an exclusively pro-inflammatory ex vivo response (TNF, IFN-γ, IL-17) to the major CMV target molecules pp65 and IE1 had a significant survival advantage over those also having anti-inflammatory responses (IL-10). These findings suggest that higher levels of naïve T cells may not necessarily be associated with a survival advantage and imply that the nature of immunosurveillance against CMV may be crucial for remaining longevity, at least in the very elderly.

Clinical factors influencing phenotype of HCMV-specific CD8+ T cells and HCMV-induced interferon-gamma production after allogeneic stem cells transplantation

Human cytomegalovirus (HCMV) infection causes significant morbidity and mortality after hematopoietic stem cell transplantation (HSCT). In this work, we characterized the phenotype and interferon-gamma (INF-γ) production of HCMV-specific T cells using QuantiFERON-HCMV assay in 26 patients 6 months after HSCT. We analysed whether these two parameters were associated with clinical variables. Our results showed that the patients receiving stem cells from donors ≥40 years old were 12 times more likely to have HCMV-specific CD8+ T cells with "differentiated phenotype" (CD45RA+CCR7+ ≤6.7% and CD28+ ≤30%) than patients grafted from donors <40 years old (OR = 12; P = 0.014). In addition, a detectable IFN-γ production in response to HCMV peptides (cutoff 0.2 IU/mL IFN-γ; "reactive" QuantiFERON-HCMV test) was statistically associated with HCMV replication after transplantation (OR = 11; P = 0.026), recipients ≥40 versus <40 years old (OR = 11; P = 0.026), and the use of peripheral blood versus bone marrow as stem cell source (OR = 17.5; P = 0.024). In conclusion, donor age is the only factor significantly associated with the presence of the "differentiated phenotype" in HCMV-specific CD8+ T cells, whereas HCMV replication after transplantation, recipient age, and stem cell source are the factors associated with the production of IFN-γ in response to HCMV epitopes.

Rapid T cell repopulation after rabbit anti-thymocyte globulin (rATG) treatment is driven mainly by cytomegalovirus

Rabbit anti-thymocyte globulin (rATG) induces a long-lasting lymphocytopenia. CD4(+) T cells remain depleted for up to 2 years, whereas the CD8(+) T cell compartment is refilled rapidly by highly differentiated CD27(-) CD45RA(+) CD57(+) effector-type cells. Because the presence of these highly differentiated CD8(+) T cells has been associated with cytomegalovirus (CMV) infection, we questioned to what extent restoration of CMV T cell immunity contributes to the re-emergence of T cells following rATG treatment. We compared T cell repopulation in six CMV-seropositive patients with CMV reactivation (reactivating CMV(+) ) to that in three CMV(+) patients without reactivation (non-reactivating CMV(+) ), and to that in three CMV-seronegative recipients receiving a kidney from a CMV-seronegative donor (CMV(-/-) ). All patients received rATG because of acute allograft rejection. Total CD4 and CD8 counts, frequency and phenotype of virus-specific CD8(+) T cells were determined. In reactivating CMV(+) patients, total CD8(+) T cells reappeared rapidly, whereas in non-reactivating CMV(+) patients they lagged behind. In CMV(-/-) patients, CD8(+) T cell counts had not yet reached pretransplant levels after 2 years. CMV reactivation was indeed followed by a progressive accumulation of CMV-specific CD8(+) T cells. During lymphocytopenia following rATG treatment, serum interleukin (IL)-7 levels were elevated. Although this was most prominent in the CMV-seronegative patients, it did not result in an advantage in T cell repopulation in these patients. Repopulated CD8(+) T cells showed increased skewing in their Vβ repertoire in both CMV(-/-) and reactivating CMV-seropositive patients. We conclude that rapid T cell repopulation following rATG treatment is driven mainly by CMV.

Immunoglobulin prophylaxis against cytomegalovirus infection in patients at high risk of infection following allogeneic hematopoietic cell transplantation

Reports on the efficacy of intravenous immunoglobulin (IVIG) prophylaxis against cytomegalovirus (CMV) infection after allogeneic hematopoietic cell transplantation (HCT) have often sparked controversy. In addition, we are not aware of any study that has examined whether prophylaxis with IVIG affects the incidence of CMV infection in high-risk patients--those who are elderly or have received human leukocyte antigen (HLA) mismatched HCT. In the present open-label, phase II study, we addressed this question. We enrolled 106 patients in the study. The cumulative incidences of CMV infection at 100 days after HCT were similar in the intervention and the control groups (68% and 64%, P=.89; 89% and 87%, P=.79, respectively, for patients 55 years or older and those who received HLA-mismatched HCT). In those who received HLA-mismatched HCT, 1-year overall survival after HCT was 46% in the intervention group and 40% in the control group (P=.31); for age≥55 years, the corresponding values were 46% and 40% (P=.27). Our data showed that prophylaxis with regular polyvalent IVIG did not affect the incidence of CMV infections or survival among older patients or those who receive HLA-mismatched HCT.

Dynamics of cell-mediated immune responses to cytomegalovirus in pediatric transplantation recipients

CMI responses, combined with quantification of CMV DNA (DNAemia), may identify transplantation recipients at risk for invasive disease. PBMC were collected in pediatric transplantation candidates at one, three, and six months post-transplant in 10 subjects (six renal, three cardiac, one stem cell) and at single time points in eight HC and 14 children greater than one yr post-transplant (LTTx). Cells were stimulated with anti-CD3mAb or CMV pp65 peptide pools and responses assessed by IFNG enzyme-linked immunosorbent spot assay and cytokine secretion. IFNG responses to anti-CD3mAb were significantly lower pretransplant relative to HC and were further decreased at one and three months post-transplant, but recovered to levels comparable to HC by six months. Responses to pp65 among CMV-seropositive recipients followed a similar pattern but recovered by three months. CMV-seropositive LTTx and HC showed a Th1 cytokine response to pp65 stimulation. Three LTTx subjects developed CMV DNAemia; two demonstrated decreased responses to anti-CD3mAB (and pp65 in the CMV seropositive subject) at the onset of DNAemia, which recovered as DNAemia resolved. Monitoring CMI in children is feasible and may provide an adjunct biomarker to predict CMV progression and recovery.

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

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.

Tetramer monitoring to assess risk factors for recurrent cytomegalovirus reactivation and reconstitution of antiviral immunity post allogeneic hematopoietic stem cell transplantation

BACKGROUND

Reactivation of cytomegalovirus (CMV) is a major cause of morbidity after allogeneic hematopoietic stem cell transplantation (HSCT). In healthy individuals, virus-specific T cells (CMV-CTL) control the reactivation of latent CMV. The monitoring of virus-epitope-binding CD8(+) T cells using major histocompatibility complex-I-peptide complexes (tetramers) has recently been established, allowing assessment of the reconstitution of CMV-CTL post HSCT.

PATIENTS AND METHODS

In order to study immune reconstitution and reactivation control through CMV-CTL, we regularly monitored all patients undergoing allogeneic HSCT in our department for 2 years, who matched at least 1 of 6 commercially available tetramers for common human leukocyte antigen (HLA) types. To verify risk factors for CMV reactivations in our cohorts, clinical characteristics of all patients transplanted within the last 10 years were included in statistical analyses determining the relative risk for single and recurrent CMV reactivations.

RESULTS

As expected, CMV serostatus, HLA match, and donor source significantly influenced the risk of recurrent CMV reactivation. Applying CMV-CTL tetramer monitoring for 2 years allowed the monitoring of 114 (85%) of 134 patients, by testing a set of tetramers representing 6 epitopes from 3 different CMV proteins. The presence of CMV-CTL before day + 50 and their expansion post reactivation seem to protect against recurrent CMV reactivations. The mean number of CMV-CTL by day +100 was >5-fold higher in the recipient CMV-positive/donor-positive (R +/D +) group (91/μL) compared with the R +/ D- (13/μL) and the R -/D +(2/μL) group. Seventy-nine percent of patients from the R +/D + setting recovered >10 CMV-CTL per μL by day + 100, while almost 50% of the other groups failed to mount a CMV-specific response by that time (R +/D -: 58%; R -/D +: 43%).

CONCLUSION

Tetramer monitoring can help to predict (recurrent) CMV reactivation and is a useful approach to monitor individual patients with increased risk for recurrent reactivation post HSCT; thus, it could help to identify patients in need of adoptive transfer of CMV-CTL or to optimize the use of antiviral drugs.

Cytomegalovirus in hematopoietic stem cell transplant recipients

This article examines the clinical manifestations of and risk factors for cytomegalovirus (CMV). Prevention of CMV infection and disease are also explored. Antiviral resistance and management of CMV are examined.

Lymphoproliferative response to herpes simplex virus type 1, cytomegalovirus, Epstein-Barr virus, varicella zoster virus, human herpes virus 6, 7, and 8 antigen stimulation in pediatric allogeneic stem cell transplant recipients

We evaluate the recovery of CMI to various herpes viruses by measuring in vitro LPR to specific recall antigens. CMI was evaluated by the in vitro LPR of PBMC to specific purified HSV-1, VZV, CMV, EBV, HHV-6, -7, -8, antigens. Results were expressed as SI. SI > or = 3 was regarded as positive LPR. Serial measurements were taken prospectively from pretransplant till 12-month post-transplant. Thirty-six patients (M = 19; F = 17) with median age 10.5 yr old were recruited. Most transplants were from MSD with PBSC as the stem cell source. Altogether 50% of subjects started to show positive LPR to HSV-1, CMV, and VZV antigens at two-month post-transplant, major upsurges were noted until 6-month post-transplant. Subjects showed positive LPR to EBV, HHV-6, HHV-7, and HHV-8 antigens were all along <50% throughout the study period. The antibody status of donor and recipient for HSV-1, CMV, and VZV were associated with the timing of recovery of CMI. Choice of donor and stem cell source were important determinants of eventual LPR to various herpes viruses at 3-month post-transplant. At 12-month post-transplant, there was no statistical difference in any parameters in affecting LPR to different herpes viruses.

Cytomegalovirus in hematopoietic stem cell transplant recipients

This article examines the clinical manifestations of and risk factors for cytomegalovirus (CMV). Prevention of CMV infection and disease are also explored. Antiviral resistance and management of CMV are examined.

Immune reconstitution and cytomegalovirus infection after allogeneic stem cell transplantation: the important impact of in vivo T cell depletion

We analyzed cytomegalovirus (CMV) infection risk factors and immune reconstitution kinetics in 89 patients after allogeneic stem cell transplantation (allo-SCT). The use of alemtuzumab for in vivo T cell depletion (TCD) had, besides the donor/recipient CMV serostatus, the strongest influence on the CMV infection risk in univariate and multivariate analyses. In comparison to without use of in vivo TCD, the CMV infection risk [hazard ratio (HR)] was 4.82-fold after TCD with alemtuzumab, but only 1.40-fold after TCD with antithymocyte globulin (ATG). Alemtuzumab strongly depressed CD4(+) and CD8(+) T cell reconstitution, whereas ATG only delayed CD4(+) T cell reconstitution. Considering the reconstitution kinetics of CD4(+) and CD8(+) T cells, CMV-specific CD8(+) T cells, NK cells and the IgG concentration, only a low day +60 NK cell count (< or =161 versus >161/microl) was significantly associated with CMV infection development (HR 2.92, p = 0.034). CMV-specific CD8(+) T cells were detected in 57% of patients with a CMV-seropositive donor, but in none of the patients with a CMV-seronegative donor on day +30 (p = 0.01). Our data indicate that the type of in vivo TCD (alemtuzumab or ATG) differentially influences both the CMV infection risk and CD4(+)/CD8(+) T cell reconstitution kinetics in patients after allo-SCT.