Immune response to CMV in solid organ transplant recipients: current concepts and future directions

Despite advances in immunosuppression and antiviral therapy, CMV continues to be a significant opportunistic pathogen adversely affecting the outcome of solid organ transplantation (SOT) recipients. While a significant proportion of CMV disease is caused by reactivation of latent virus, the risk is highest among CMV donor+ and recipient- SOT patients. CMV is responsible for both direct (e.g., pneumonitis, colitis) and indirect (e.g., rejection, atherosclerosis) morbidity and mortality. Healthy CMV-seropositive individuals have a high frequency of CMV-specific CD4⁺ and CD8⁺ T cells that provide immune protection by limiting CMV reactivation and replication. Changes to the innate and adaptive immune system from immunosuppressive therapy following SOT contribute to CMV disease pathogenesis. CMV disease after SOT is associated with poorer outcomes, thus novel strategies to prevent it are an area of active research. In this article, we review the current state of knowledge on the immune response to CMV following SOT.     

Clinical significance of human cytomegalovirus viruria and the effect of antiviral therapy in hematopoietic stem cell transplant recipients

BackgroundCytomegalovirus (CMV) causes life-threatening infections in immunocompromised host. The clinical significance of asymptomatic CMV viruria in patients receiving hematopoietic stem cell transplantation (HSCT) remains unclear. This study aims to clarify whether antiviral therapy is associated with a favorable clinical outcome.MethodsHSCT recipients whose urine was culture-positive for CMV were retrospectively reviewed and followed. Viruria episodes were divided according to whether or not antiviral therapy was used. Mortality and the estimated glomerular filtration rate (eGFR) in 2 years following CMV viruria were compared between patients with and without antiviral therapy.ResultsSixty-two episodes of culture-proven asymptomatic CMV viruria were identified in 28 HSCT recipients. Antiviral therapy was used in 35 (56.5%) and spared in 27 (43.5%) viruric episodes. Compared with the baselines, there were no significant difference in the decrements of eGFR between the two groups at the end the 1st year (4.78 vs 5.02 mL/min/1.73 m², p = 0.968) and the 2nd year (1.13 vs 7.66 mL/min/1.73 m², p = 0.276). Antiviral therapy for asymptomatic CMV viruria was also not associated with a favorable survival (p = 0.288). On the other hand, presence of CMV viremia correlated with a poorer survival (2-year mortality rate 60% vs 13.33%, p < 0.001).ConclusionAntiviral therapy for asymptomatic CMV viruria is not associated with a clear clinical benefit in HSCT recipients. Further studies may be needed to identify if specific patient populations may benefit from antiviral therapy in CMV viruria.     

CMV driven CD8 T-cell activation is associated with acute rejection in lung transplantation

Lung transplantation is the definitive treatment for terminal respiratory disease, but the associated mortality rate is high. Acute rejection of the transplanted lung is a key determinant of adverse prognosis. Furthermore, an epidemiological relationship has been established between the occurrence of acute lung rejection and cytomegalovirus infection. However, the reasons for this association remain unclear. Here, we performed a longitudinal characterization of CMV-specific T-cell responses and immune activation status in the peripheral blood and bronchoalveolar lavage fluid of forty-four lung transplant patients. Acute rejection was associated with high levels of cellular activation in the periphery, reflecting strong CMV-specific CD8⁺ T-cell activity post-transplant. Peripheral and lung CMV-specific CD8⁺ T-cell responses were very similar, and related to the presence of CMV in the transplanted organ. These findings support that activated CMV-specific CD8⁺ T-cells in the lung may play a role in promoting acute rejection.     

Regular monitoring of cytomegalovirus-specific cell-mediated immunity in intermediate-risk kidney transplant recipients: predictive value of the immediate post-transplant assessment

Objective

Previous studies on monitoring of post-transplant cytomegalovirus (CMV)-specific cell-mediated immunity (CMI) are limited by single-centre designs and disparate risk categories. We aimed to assess the clinical value of a regular monitoring strategy in a large multicentre cohort of intermediate-risk kidney transplant (KT) recipients.

Comparison of Cytomegalovirus (CMV) Enzyme-Linked Immunosorbent Spot and CMV Quantiferon Gamma Interferon-Releasing Assays in Assessing Risk of CMV Infection in Kidney Transplant Recipients

Assessing cytomegalovirus (CMV)-specific cell-mediated immunity (CMI) represents an appealing strategy for identifying transplant recipients at risk of infection. In this study, we compared two gamma interferon-releasing assays (IGRAs), Quantiferon-CMV and CMV enzyme-linked immunosorbent spot (ELISPOT), to determine the ability of each test to predict protective CMV-specific T-cell responses. Two hundred twenty-one Quantiferon-CMV and ELISPOT tests were conducted on 120 adult kidney transplant recipients (KTRs), including 100 CMV-seropositive transplant recipients (R⁺) and 20 CMV-seronegative transplant recipients of a CMV-positive donor (D⁺/R⁻). As a control cohort, 39 healthy adult subjects (including 33 CMV-seropositive and 6 CMV-seronegative subjects) were enrolled. CMV IgG serology was used as a reference for both tests. In the CMV-seropositive individuals, the ELISPOT and Quantiferon-CMV assays provided 46% concordance with the serology, 12% discordance, 18% disagreement between ELISPOT or Quantiferon-CMV and the serology, and 24% gray areas when one or both tests resulted in weak positives. None of the CMV-seronegative subjects showed detectable responses in the ELISPOT or the Quantiferon-CMV test. In transplant recipients, both the ELISPOT and Quantiferon-CMV assays positively correlated with each other and negatively correlated with CMV DNAemia in a significant way (P < 0.05). During the antiviral prophylaxis, all 20 D⁺/R⁻ KTRs we examined displayed undetectable Quantiferon-CMV and ELISPOT results, and there was no evidence of CMV seroconversion. The receiving operator curve (ROC) statistical analysis revealed similar specificities and sensitivities in predicting detectable viremia (areas under the curve [AUC], 0.66 and 0.62 for Quantiferon-CMV and ELISPOT, respectively). ELISPOT and Quantiferon-CMV values of >150 spots/200,000 peripheral blood mononuclear cells (PBMCs) and >1 to 6 IU gamma interferon (IFN-γ) were associated with protection from CMV infection (odds ratios [OR], 5 and 8.75, respectively). In transplant recipients, the two tests displayed similar abilities for predicting CMV infection. Both the ELISPOT and Quantiferon-CMV assays require several ameliorations to avoid false-negative results.     

Bacterial and fungal bloodstream infections in solid organ transplant recipients: results from a Danish cohort with nationwide follow-up

ObjectivesBloodstream infections (BSI) are prevalent after solid organ transplantation (SOT). In this study, we aimed to investigate the incidence and risk factors for BSI in the first 5 years post-transplantation.MethodsThe study included 1322 SOT (kidney, liver, lung and heart) recipients transplanted from 2010 to 2017 with a total of 5616 years of follow-up. Clinical characteristics and microbiology were obtained from the Centre of Excellence for Personalized Medicine of Infectious Complications in Immune Deficiency (PERSIMUNE) data repository with nationwide follow-up. Incidence was investigated in the different SOT groups. Risk factors associated with BSI were assed in the combined group in time-updated multivariable Cox regressions.ResultsThe cumulative incidence of first BSI in the first 5 years post-transplantation differed in the SOT groups with a lower incidence in heart transplant recipients than in the other SOT groups (heart: 4.4%, CI 0.0–9.7%, vs. kidney: 24.6%, CI 20.9–28.2%, liver: 24.7%, CI 19.4–29.9%, and lung: 19.6%, CI 14.5–24.8%, p <0.001). Age above 55 years (HR 1.71, CI 1.2–2.4, p=0.002) and higher Charlson comorbidity index score (HR per unit increase: 1.25, CI 1.1–1.4, p<0.001) at transplantation, current cytomegalovirus (CMV) infection (HR 4.5, CI 2.6–7.9, p<0.001) and current leucopenia (HR 13.3, CI 3.7–47.9, p<0.001) were all associated with an increased risk of BSI.ConclusionIn SOT recipients, the incidence of BSI differed with the type of transplanted organ. Risk of BSI was higher in older recipients and in recipients with comorbidity, current CMV infection or leucopenia. Thus, increased attention towards BSI in recipients with these characteristics is warranted.     

Immune-based monitoring for cytomegalovirus infection in solid organ transplantation: is it ready for clinical primetime?

The impact of CMV infection and disease in solid organ transplant (SOT) recipients continues despite remarkable improvements in its prevention and management with antiviral drugs. Studies that have investigated the host immune response to CMV have paved way for the development of novel immune-based assays that are anticipated to complement the current antiviral-based strategies for CMV management after transplantation. In this article, we review the emerging data on the clinical application of innovative CMV-specific T-cell assays, including their role in risk-stratification, prognostication, prevention and treatment of CMV infection and disease in SOT recipients.     

Going beyond serology for stratifying the risk of CMV infection in transplant recipients

Knowledge of donor and recipient (D/R) cytomegalovirus (CMV) serostatus is critical for risk stratification of CMV infection and disease in transplant recipients, particularly in the solid organ transplantation (SOT) setting. Despite its broad availability and the success of it use, the risk stratification based on the D/R serostatus is not free of limitations since there are a nondepreciable number of patients that are not accurately categorized by this approach. In fact, up to 20% of seropositive SOT recipients, classically considered at intermediate risk, develop episodes of CMV infection and disease after transplantation. Here, we provide an overview of additional donor and recipient factors that may have utility in identifying patients at risk for post‐transplant CMV infection. Specifically, we summarize our current understanding regarding the potential use of use CMV‐specific T‐cell‐mediated immunity, neutralizing antibodies and host genetics that may influence the risk of CMV infection and disease. We provide an overview of the benefits and limitations associated with using these immunological factors in risk stratification and propose specific variables that could be analyzed at the pretransplant evaluation to improve the identification of patients with increased individual susceptibility.     

CD28 positive,cytomegalovirus specific cytotoxic T lymphocytes as a novel biomarker associated with cytomegalovirus viremia in kidney allorecipients

BackgroundCMV infection remains major complication after kidney transplantation, thus diagnostics tools that would improve identification of individuals at risk of development of CMV − related complications are useful. For this reason, searching for proper immunological biomarkers candidates gives hope to individualize antiviral therapy and minimize side effects of antiviral drugs.ObjectivesThe purpose of this research was to assess immune assays that can be used to predict the likelihood of CMV viremia after kidney allotransplantation.Study designIn the study, immunological markers of CMV viremia were assessed in 52 kidney transplant recipients during two years lasting follow–up. Immunological markers associated with viral infection, like lymphocytosis, cytotoxic T lymphocytes (CTL) and serum cytokines levels were compared with less common immunological assays, like activated T lymphocytes, CMV-specific CTL stratified according to naïve/memory phenotype. The test to assess expression of CD28 antigen on CTL, as a possible additional marker of CMV-specificity, was developed.ResultsCD28-positive CMV-specific CTL have been found the most useful marker for CMV viremia prediction. Tested value of 3 cells/μl was found to be most suitable for CMV activation assessment with acceptable sensitivity and specificity.DiscussionThis preliminary report suggests that CD28-positive CMV-specific CTL could be put at the first line, as possible novel marker associated with CMV viremia development.     

Clinical significance of CMV-specific T helper responses in lung transplant recipients

Background. Cytomegalovirus (CMV) disease continues to be a major problem for lung transplant patients who generate an inefficient immune response to control this viral infection. Both T helper and cytotoxic T cells are thought to play an important role in prevention and control of CMV disease. We investigated the clinical significance of CMV-specific memory responses in lung transplant recipients. Method. Peripheral blood samples (140) were collected from 99 lung transplant recipients. Patients were grouped according to their pre-transplant CMV serological status as recipient/donor (R−/D+, 25 patients), 28 R+/D+ patients, 35 R+/D− patients and 11 R−/D− patients. Memory responses to CMV whole antigen, 5 CMV proteins, and tetanus toxoid (TT) were measured in a 6-day proliferative assay. Results were expressed as the stimulation index (SI = experimental cpm/background cpm), and were considered positive if the SI was >3 and the cpm values were over 1,000. Results. The frequency of positive CMV memory responses was similar in three groups: 64% for R−/D+, 63% for R+/D+ and 56% for R+/D− except for R−/D− (21%). The memory response to TT was similar for all four groups (70% of samples were positive). The level of responsiveness to individual CMV proteins was much higher in R+/D+ group (65%) than the other two groups (35% for R+/D−, and 31% for R−/D+). We determined the temporal relationship between the presence of CMV-specific memory responses and the diagnosis of CMV disease. In the R−/D+ group, 16 of 17 patients who had CMV disease eventually developed CMV-specific memory. In those patients (n = 3) who failed to develop CMV-specific T helper response for a prolonged time, all had recurrent CMV disease. In the R+/D+ group, 4 of 8 patients with CMV disease exhibited CMV-specific memory responses. Three of 4 patients in whom we observed a persistent absence of CMV-specific memory had multiple episodes of CMV pneumonitis. In the R+/D− group, only one of 4 patients with CMV disease had suppressed CMV-specific memory response after first episode of CMV pneumonitis and had recurrent disease. Conclusion. In lung transplant recipients, the loss or persistent lack of CMV-specific memory following infection was associated with chronic CMV disease. These data suggest that monitoring T helper memory responses following primary CMV infection or after augmented immunosuppression for treatment of rejection may identify those patients at risk for morbidity associated with recurrent CMV disease.     

High risk of cytomegalovirus infection following solid organ transplantation despite prophylactic therapy

Cytomegalovirus infection (CMV) in solid organ transplant recipients is a major clinical problem. The aim of this study was to evaluate the incidence of CMV infection and its association with mortality during the first year after transplantation in a large solid organ transplant cohort at the Royal Infirmary of Edinburgh between January 2006 and April 2009. Data including the use of CMV prophylaxis, nature of CMV disease, treatment and deceased date (when appropriate) was collected retrospectively using hospital databases and patient notes for all transplanted patients with detectable CMV viraemia. The outcomes between recipients of kidney and liver transplants in the four CMV donor/recipient serostatus categories (D+R+, D?R?, D+R?, D?R+) were compared. A total of 428 individuals were included. Despite the administration of valganciclovir prophylaxis, CMV disease (syndrome or end‐organ involvement) was diagnosed within the year of transplantation in the D+R?‐group in 31.3% of liver and 19.2% of kidney recipients. All D+R? transplant recipients that received CMV‐prophylaxis presented with late‐onset CMV disease. Furthermore, the rate of CMV disease in the D+R+‐group was markedly higher in renal graft recipients compared to liver recipients (22% vs. 5%). The highest mortality was observed among the D+R+ liver and kidney graft recipients with CMV infection. The high incidence of late‐onset CMV disease in D+R? transplant recipients receiving CMV prophylaxis demonstrates that CMV disease remains an important problem after organ transplantation. Furthermore, the surprisingly high mortality in the D+R+‐transplant patients with CMV viraemia highlights the need for proactive monitoring of this group. J. Med. Virol. 85:893–898, 2013. © 2013 Wiley Periodicals, Inc.     

Immune response to CMV in solid organ transplant recipients: current concepts and future directions

Despite advances in immunosuppression and antiviral therapy, CMV continues to be a significant opportunistic pathogen adversely affecting the outcome of solid organ transplantation (SOT) recipients. While a significant proportion of CMV disease is caused by reactivation of latent virus, the risk is highest among CMV donor+ and recipient- SOT patients. CMV is responsible for both direct (e.g., pneumonitis, colitis) and indirect (e.g., rejection, atherosclerosis) morbidity and mortality. Healthy CMV-seropositive individuals have a high frequency of CMV-specific CD4(+) and CD8(+) T cells that provide immune protection by limiting CMV reactivation and replication. Changes to the innate and adaptive immune system from immunosuppressive therapy following SOT contribute to CMV disease pathogenesis. CMV disease after SOT is associated with poorer outcomes, thus novel strategies to prevent it are an area of active research. In this article, we review the current state of knowledge on the immune response to CMV following SOT.     

Properties of CD4(+) T cells in human cytomegalovirus infection

The correlates of protective immunity to disease-inducing viruses in man remain to be elucidated. We determined the kinetics and properties of cytomegalovirus (CMV)-specific CD4(+) T cells in healthy individuals and renal transplant recipients during different stages of CMV infection. Our data reveal that circulating CMV-specific CD4(+) T cells displayed an effector-memory phenotype, and produced the T helper 1 cytokines interferon-gamma and tumor necrosis factor-alpha. In addition, they lacked molecules for secondary lymphoid organ homing and expressed the cytotoxic molecule granzyme B, inferring a direct role of these cells at target sites of infection. In asymptomatic individuals the CMV-specific CD4(+) T-cell response preceded CMV-specific CD8(+) T-cell responses, whereas in symptomatic individuals the CMV-specific effector memory CD4(+) T-cell response was delayed and only detectable after antiviral therapy. The appearance of disease symptoms in these patients suggests that functional CD8(+) T cell and antibody responses are insufficient to control viral replication and that formation of effector memory CD4(+) T cells is necessary for recovery of infection.     

Simultaneous Monitoring of Cytomegalovirus-Specific Antibody and T-cell levels in Seropositive Heart Transplant Recipients

Purpose

Human cytomegalovirus (CMV) active infection (CMV infection) poses serious risks to CMV-seropositive heart transplant recipients. We evaluated the usefulness of simultaneous assessment of CMV-specific values for parameters of the humoral (antibodies) and cellular (CD4+ and CD8+ T-cells) immune responses in the identification of heart recipients at risk of developing CMV infection after transplantation.

Methods

We prospectively studied 38 CMV-seropositive heart recipients. Anti-CMV antibody titers were assessed using enzyme-linked immunosorbent assays. CD4+ and CD8+ T-cell responses to overlapping peptide pools of the CMV proteins pp65 and immediate early protein-1 (IE1) were evaluated by flow cytometry. Immunological studies were performed before transplantation and at 30?days after transplantation. Patients with CMV infection were compared with heart recipients without CMV infection.

Results

During the 6-month follow-up period, 13 (34.2%) patients developed CMV infection. At baseline, the mean anti-CMV-IgG antibody titer was lower in patients who developed CMV infection. This difference remained at 30?days after transplantation. One month after transplantation, the mean percentage of IE1-specific CD8+ T cells that are IFNg-positive (CD8/IFNg?+?IE1) was lower in CMV-infected patients. The predictive value of these variables at 30?days was increased when they were combined. Cox regression analysis revealed an association between the risk of developing CMV infection and the combination marker (low anti-CMV titer [<16,100] and low CD8/IFNg?+?IE1 percentages [<0.40%], relative hazard, 6.07; p?=?0.019). The combination marker remained significant after adjustment for clinical variables.

Conclusions

This novel approach of a simultaneous assessment of specific anti-CMV antibody titers and CD8/IFNg?+?IE1 percentages might help identify heart transplant recipients with an increased risk of developing CMV infection.     

Bone marrow transplantation from a pediatric donor with a high frequency of cytomegalovirus-specific T-cells

A recent study reported that quantitation of cytomegalovirus (CMV)-specific CD8+ T lymphocytes in the graft and monitoring of these T cells might identify hematopoietic stem cell transplantation-recipients at the risk for progressive CMV infection. A 6-year-old girl underwent bone marrow transplantation from an HLA-identical sibling with a very high frequency of CMV specific tetramer-positive CD8+ T-cells. CMV-specific T-cell immunity was prospectively evaluated using a peptide (HLA-A2, NLVPMVATV). Tetramer assay showed that the frequency of CMV-specific CD8+ T cells of the donor in the peripheral blood was 5.3%, higher than average amongst young children. The frequency of CMV-specific CD8+ T cells of the donor in the graft was 3.7% of CD8+ T-cells. Before transplantation, the frequency of CMV specific CD8+ T cells of the recipient was 0.1% in the peripheral blood. Surprisingly, the frequency of CMV specific CD8+ T cells increased up to 30% of CD8+ T-cells at day 27 after transplantation. IFN-gamma enzyme-linked immunospot assay showed the recipient-T cells had strong responses to the A2-specific NLVPMVATV peptide. Although the phenotypic pattern of the CMV-specific T cells of the recipient was different from those of the donor before transplantation, the phenotype of the donor-derived cells retained their original phenotype in the recipient after transplantation. These finding suggested that active transferred immunity from the graft with a high frequency of CMV-specific CTL could induce a rapid reconstitution of CMV-specific T-cell mediated immunity in pediatric HLA-identical allogenetic bone marrow transplantation. The screening of peripheral blood using HLA-peptide tetramer staining might be beneficial to select donors.     

Prospective long-term study on primary CMV infections in adult liver transplant (D+/R−) patients after valganciclovir prophylaxis

BackgroundCytomegalovirus (CMV) can cause severe infections in transplanted patients. To prevent CMV infection, most liver centers use prophylaxis for CMV-seronegative recipients receiving an organ from a seropositive donor (D+/R−). Valganciclovir is mostly given for 3–6 months after transplantation. However, the patients may develop primary CMV infection after the cessation of prophylaxis and late-onset CMV disease may occur.ObjectivesA prospective long-term follow-up of CMV (D+/R−) adult liver transplant recipients after 3 months valganciclovir prophylaxis was investigated.Study designOf 154 consecutive adult liver recipients transplanted from 2006 to 2009, 20 (13%) were CMV D+/R− and received antiviral prophylaxis up to 3 months after transplantation. After excluding the recipients with incomplete prophylaxis or monitoring, 13 (D+/R−) patients with follow-up of >4 years after the 3-month period of valganciclovir prophylaxis were included in the study.The patients were monitored for CMV by real-time quantitative plasma PCR.ResultsNo break-through CMV infections were recorded during the prophylaxis period. After cessation of valganciclovir prophylaxis 12/13 (90%) patients demonstrated CMV-DNAemia following a post transplantation mean interval of 165 days (range 95–320). Ten patients with high viral loads (peak viral load mean 81,510, range 1900–648950 cps/ml) were successfully treated, 6 with valganciclovir, and 4 with ganciclovir. Two patients with low level CMV-DNAemia (<1000 cps/ml) were asymptomatic and not treated. No intragraft infection was seen, but one patient developed gastrointestinal CMV infection verified from ileum biopsy. During long-term follow-up, 3 patients demonstrated low-level viral replication, but no symptomatic recurrences occurred. One patient died of bacterial sepsis, but no patient or graft was lost due to CMV.ConclusionsPrimary CMV infections after cessation of prophylaxis were common, but were successfully treated with valganciclovir or ganciclovir.     

Systematic review of ganciclovir pharmacodynamics during the prevention of cytomegalovirus infection in adult solid organ transplant recipients

Human cytomegalovirus (CMV) represents the most common infection among recipients of solid organ transplants (SOTs). Previous meta‐analysis showed 0.8% of SOT recipients developed CMV disease whilst receiving valganciclovir (ValGCV) prophylaxis. However, the clinical utility of monitoring ganciclovir (GCV) blood concentrations is unclear. We systematically reviewed the association between GCV concentrations during prophylaxis and the incidence of CMV. MEDLINE and EMBASE databases were searched for studies between 1946 and 2018, where GCV pharmacokinetics and incidence of CMV viraemia or disease in SOT were available. Research designs included randomised trials, comparative, prospective cohort, retrospective, or case report studies. Only human adult studies were included, with English language restriction. The 11 studies that met the eligibility criteria included 610 participants receiving GCV or ValGCV prophylaxis. Quality assessment showed 2/4 randomised trials, 4/6 cohort studies, and 1/1 case report were of high quality. Despite dose adjustments for renal impairment, mean GCV exposures for patients were heterogeneous and ranged between 28 and 53.7 μg·h/mL across three randomised trials. The incidence of CMV infection and disease ranged from 0% to 50% and 0% to 3.1%, respectively, with follow up between 3 to 9 months. One study showed statistical power in determining relationship, where GCV exposure at 40 to 50 μg·h/mL in high‐risk SOT recipients was associated with a reduced risk of viraemia. Clinical monitoring for GCV exposure can be applied to high‐risk SOT recipients during ValGCV prophylaxis; however, further studies are needed to determine the utility of monitoring in all SOT recipients.     

Ex vivo monitoring of human cytomegalovirus‐specific CD8+ T‐Cell responses using the QuantiFERON®‐CMV assay in allogeneic hematopoietic stem cell transplant recipients attending an Irish hospital

Reconstitution of human cytomegalovirus (HCMV) T‐cell immunity is crucial in hematopoietic stem cell transplant (HSCT) recipients. The QuantiFERON®‐CMV assay for cellular HCMV‐specific immunity was evaluated in allogeneic HSCT recipients (n = 43) and patients with hematological malignancies (n = 29) attending a tertiary‐care Irish hospital. An intracellular cytokine (ICC) assay correlated with the QuantiFERON®‐CMV assay. Although there was agreement between HCMV seropositivity and QuantiFERON®‐CMV assay, six HCMV seropositive immunosuppressed patients with hematological malignancy had negative QuantiFERON®‐CMV results. The 43 HSCT recipients were classified as high risk (D^?/R⁺) (n = 18), intermediate risk (D⁺/R⁺ and D⁺/R^?) (n = 17), and low risk (D^?/R^?) (n = 8). During episodes of HCMV DNAemia no evidence of HCMV‐specific immunity was found using the QuantiFERON®‐CMV assay. Furthermore, the recovery of HCMV‐specific CD8⁺ T‐cell responses in high‐risk seropositive recipients of matched unrelated donors was severely delayed, a mean of 200 (SD = 117) days compared to 58 (SD = 23) days for sibling donors (P ≤ 0.028). In addition, three patients with late HCMV infection (infection >100 days post‐transplant) had delayed reconstitution of HCMV‐specific CD8⁺ T cells. Interestingly, two recipients (R⁺/D^?) developed rapid immune reconstitution by days 15 and 36 post‐HSCT, suggesting HCMV‐specific T‐cell lymphopoiesis of recipient origin. Levels of CD8⁺ T‐cell immunity in HCMV seropositive HSCT recipients were lowest following HSCT. A high number (33%) of indeterminate results was observed immediately after transplantation. Patients with indeterminate QuantiFERON®‐CMV results had low levels of HCMV‐specific CD8⁺ T cells. J. Med. Virol. 82:433–440, 2010. © 2010 Wiley‐Liss, Inc.     

Clinical significance of the single nucleotide polymorphism TLR2 R753Q in heart transplant recipients at risk for cytomegalovirus disease

BackgroundThe toll-like receptor 2 (TLR2) is a significant component of innate immunity against cytomegalovirus (CMV) infection but information on the clinical significance of the single nucleotide polymorphism (SNP) (R753Q) is conflicting.ObjectivesThe inconsistent observations of the immunological and clinical significance of the TLR2 R753Q polymorphism for CMV infection indicates the influence of confounders.Study designThe presence of the TLR2 polymorphism was determined by a genotyping assay of 175 HTX patients and 281 healthy blood donors and evaluated in relation to selected virological and clinical parameters.ResultsRelative frequency of TLR2 polymorphism was similar in HTX patients and blood donors (homozygous wild-type, 94.3% vs. 94.0%; heterozygous, 5.1% vs. 5.7%; homozygous mutated, <1%). CMV viremia was detectable in 108 (61.7%) of HTX patients. The TLR2 polymorphism was neither associated with occurrence or level of CMV infection nor with survival, graft failure or rejection, or CMV serostatus of patient before transplantation. Nevertheless, CMV viremia occurred in 83.1% of R+/D+, 77.1% of R+/D-, and 64.3% of R-/D+ patients. Time of first CMV viremia was in R-/D+ patients later than in CMV-seropositive patients (median, 182 days versus 23 days; P < 0.001) corresponding to the duration of antiviral prophylaxis in R-/D+ patients.ConclusionsThe TLR2 R753Q polymorphism is extremely rare in the general population and HTX patients. Screening for this risk factor of CMV disease may not be cost-effective in contrast to testing for CMV viremia.     

Coupled regulation of interleukin-12 receptor beta-1 of CD8+ central memory and CCR7-negative memory T cells in an early alloimmunity in liver transplant recipients

This study investigated how CD8⁺ T cell subsets respond to allo‐ and infectious immunity after living donor liver transplantation (LDLT). Early alloimmunity: 56 recipients were classified into three types according to the post‐transplant course; type I demonstrated uneventful post‐transplant course, type II developed severe sepsis leading to multiple organ dysfunction syndrome or retransplantation and type III with acute rejection. In 23 type I recipients, the interleukin (IL)‐12 receptor beta‐1 (Rβ1)⁺ cells of central memory T cells (Il‐12Rβ1⁺ T_CM) were increased above the pretransplant level. In 16 type II recipients, IL‐12Rβ1⁺ T_CM was decreased markedly below the pretransplant level on postoperative day (POD) 5. In 17 type III recipients, IL‐12Rβ1⁺ T_CM was decreased for a more prolonged period until POD 10. Along with down‐regulation of IL‐12Rβ1⁺ T_CM, the IL‐12Rβ1⁺ cells of CCR7‐negative subsets (CNS) as well as perforin, interferon (IFN)‐γ and tumour necrosis factor (TNF)‐α decreased gradually, resulting in the down‐regulation of effectors and cytotoxicity. The down‐regulation of IL‐12Rβ1⁺ T_CM was suggested to be due to the recruitment of alloantigen‐primed T cells into the graft, and then their entry into the secondary lymphoid organ, resulting in graft destruction. Infectious immunity: immunocompetent memory T cells with the capacity to enhance effectors and cytotoxicity were generated in response to post‐transplant infection along with both up‐regulation of the IL‐12Rβ1⁺ T_CM and an increase in the CNS showing the highest level of IL‐12Rβ1⁺ cells. In conclusion, this work demonstrated that the IL‐12Rβ1⁺ cells of T_CM and CNS are regulated in a tightly coupled manner and that expression levels of IL‐12Rβ1⁺ T_CM play a crucial role in controlling allo‐ and infectious immunity.