Absolute Lymphocyte Count: A Predictor of Recurrent Cytomegalovirus Disease in Solid Organ Transplant Recipients

Resurgence of BK virus following Covid-19 in kidney transplant recipients

Kidney transplant recipients have been supposed vulnerable to severe Covid-19 infection, due to their comorbidities and immunosuppressive therapies. Mild-term complications of Covid-19 are currently unknown, especially in this population. Herein, we report two cases of BKV replication after non-severe SARS-CoV-2 infection. The first case was a 59-year-old man, transplanted 3 months ago, with recent history of slight BKV viremia (3.3 log₁₀ DNA copies/ml). Despite strong reduction of maintenance immunosuppression (interruption of mycophenolic acid and important decrease of calcineurin inhibitors), BKV replication largely increased after Covid-19 and viremia persisted at 4.5 log copy/ml few months later. The second case was a 53-year-old woman, transplanted 15 years ago. She had a recent history of BKV cystitis, which resolved with a decrease of MPA dosage. Few weeks after SARS-CoV-2 infection, she presented recurrence of lower urinary tract symptoms. Our reports highlight that SARS-CoV-2 infection, even without severity, could disrupt immune system and particularly lymphocytes, thus leading to viral replication. Monitoring of viral replications after Covid-19 in kidney transplant recipients could permit to confirm these preliminary observations.

Time-dependent lymphocyte count after transplantation is associated with higher risk of graft failure and death

The transplantation field requires the identification of specific risk factors associated with the level of immunosuppression. Here, our aim was to analyze the association between the number of circulating lymphocytes, monitored routinely by complete blood cell counts during outpatient visits, and patient and graft survival. In total, 2,999 kidney or combined kidney-pancreas recipients transplanted between 2000 and 2016, from two University hospitals, were enrolled. We investigated the etiological relationship between time-dependent lymphocyte count beyond one year after transplantation and patient and graft survival, viral infection and cancer risk using time-dependent multivariate Cox models. Model 1 considered kidney function at one year and model 2 as time-dependent variable. At the time of inclusion (one year after transplantation), 584 patients (19.4%) had deep lymphopenia (under 750 /mm³) and 1,072 (35.7%) had a normal count (over 1,500 /mm³). A patient with deep lymphopenia at a given follow-up time had significantly higher risks of graft failure, death and viral infection than comparable patients with a normal lymphocyte count at the same time point. Thus, after the first year of transplantation, the occurrence of deep lymphopenia within a patient's follow-up is a risk factor for long-term graft failure, death and viral infection.

Kidney transplantation using lymphocyte depleting induction and standard maintenance immunosuppression at the height of the SARS-CoV-2 pandemic in New York City: A single-center experience

BACKGROUND

Concerns have been raised regarding proceeding with kidney transplantation using standard immunosuppression in COVID-19 endemic areas.

METHODS

We performed a single-center review of all adult kidney transplants performed during the COVID-19 pandemic in New York City. Patients were managed with standard immunosuppression protocols, including lymphocyte depleting induction and trough-guided tacrolimus. Retrospective data were collected for 3 months from the date of transplantation or until study conclusion (5/7/2020). The primary outcomes assessed included patient and allograft survival as well as COVID-19 related hospital readmission.

RESULTS

30 kidney transplants were performed during the height of the COVID-19 pandemic. After a median follow-up of 51.5 days, 93.3% of patients were alive with 100% death-censored allograft survival. 9 patients were readmitted to the hospital during the study period, 4 (13.3%) related to infection with COVID-19. Infections were mild in 3/4 patients, with one patient developing severe disease leading to respiratory failure. Patients readmitted with COVID-19 were numerically more likely to be African American, have a BMI > 30 kg/m², have a lymphocyte count ≤ 300 cells/mL, and be on maintenance corticosteroids.

CONCLUSIONS

Kidney transplantation in areas endemic to COVID-19 using standard induction and maintenance immunosuppression appears to be associated with a modest risk for severe COVID-19 related disease.

Immunosuppressive Agents and Infectious Risk in Transplantation: Managing the "Net State of Immunosuppression"

Successful solid organ transplantation reflects meticulous attention to the details of immunosuppression, balancing risks for graft rejection against risks for infection. The 'net state of immune suppression' is a conceptual framework of all factors contributing to infectious risk. Assays which measure immune function in the immunosuppressed transplant recipient relative to infectious risk and allograft function are lacking. The best measures of integrated immune function may be quantitative viral loads to assess the individual's ability to control latent viral infections. Few studies address adjustment of immunosuppression during active infections. Thus, confronted with infection in solid organ recipients, the management of immunosuppression is based largely on clinical experience. This review examines known measures of immune function and the immunologic effects of common immunosuppressive drugs and available studies reporting modification of drug regimens for specific infections. These data provide a conceptual framework for the management of immunosuppression during infection in organ recipients.

Cytomegalovirus infection after liver transplantation

Human cytomegalovirus (CMV) represents the most common opportunistic infection in liver transplant recipients. CMV infections in post liver transplant patients cause significant morbidity and mortality, directly affecting post-transplant outcomes. This review will provide the framework for the surveillance, diagnosis, prophylaxis and treatment of CMV in the liver transplant population.

A Polyclonal Immune Function Assay Allows Dose-Dependent Characterization of Immunosuppressive Drug Effects but Has Limited Clinical Utility for Predicting Infection on an Individual Basis

Dosage of immunosuppressive drugs after transplantation critically determines rejection and infection episodes. In this study, a global immune function assay was characterized among controls, dialysis-patients, and transplant-recipients to evaluate its utility for pharmacodynamic monitoring of immunosuppressive drugs and for predicting infections. Whole-blood samples were stimulated with anti-CD3/toll-like-receptor (TLR7/8)-agonist in the presence or absence of drugs and IFN-γ secretion was measured by ELISA. Additional stimulation-induced cytokines were characterized among T-, B-, and NK-cells using flow-cytometry. Cytokine-secretion was dominated by IFN-γ, and mainly observed in CD4, CD8, and NK-cells. Intra-assay variability was low (CV = 10.4 ± 6.2%), whereas variability over time was high, even in the absence of clinical events (CV = 65.0 ± 35.7%). Cyclosporine A, tacrolimus and steroids dose-dependently inhibited IFN-γ secretion, and reactivity was further reduced when calcineurin inhibitors were combined with steroids. Moreover, IFN-γ levels significantly differed between controls, dialysis-patients, and transplant-recipients, with lowest IFN-γ levels early after transplantation (p < 0.001). However, a single test had limited ability to predict infectious episodes. In conclusion, the assay may have potential for basic pharmacodynamic characterization of immunosuppressive drugs and their combinations, and for assessing loss of global immunocompetence after transplantation, but its application to guide drug-dosing and to predict infectious on an individual basis is limited.

Nuclear factor of activated T cells as potential pharmacodynamic biomarker for the risk of acute and subclinical rejection in de novo liver recipients

BACKGROUND & AIMS

Nuclear factor of activated T cell-regulated gene expression (NFAT-RGE) has been proposed as a pharmacodynamic biomarker for tacrolimus (Tac) and cyclosporine (CsA). Our aim was to evaluate the role of NFAT-RGE in modulating intralymphocytary IL-2 and IFN-γ expression and its clinical utility as an early non-invasive predictive biomarker for the risk of acute rejection (AR) and infection in de novo liver transplant (LT) recipients.

METHODS

Fifty-six LT recipients treated with Tac or CsA [with and without mycophenolate mofetil (MMF)] were included: 30 free of rejection or infection, 11 rejectors (T cell-mediated acute rejection), 5 with subclinical rejection (SCR) and 10 with cytomegalovirus (CMV) infection. Within the first 3 months after transplantation, NFAT-RGE of IL-2, IFN-γ and GM-CSF and intralymphocytary synthesis of IL-2 and IFN-γ were evaluated by real-time PCR and flow cytometry respectively.

RESULTS

A significant increase in NFAT-RGE was observed in patients who experienced TCMAR (75% [42-100%]) or SCR (41% [18-78%]) compared with patients without rejection or infection (14% [2-23%]). Positive correlations between the %NFAT-RGE-IFN and both the %CD8CD69IFN-γ and %CD4CD69IFN-γ and between the %NFAT-RGE-IL2 and the %CD8CD69IL2 were observed. NFAT-RGE was significantly lower in CMV⁺ patients than in non-infected patients. Finally, an inverse correlation between the Tac or CsA concentration and inhibition of NFAT-RGE were observed.

CONCLUSIONS

Sequential post-transplantation NFAT-RGE monitoring combined with intralymphocytary IL-2 and IFN-γ before transplantation and at the first and third month post-transplantation may be key predictive and diagnostic biomarkers for the risk of TCMAR and SCR and better guide CNi therapy in LT patients.

Predictive tools to determine risk of infection in kidney transplant recipients

Introduction: Infection represents a major complication after kidney transplantation (KT). Therapeutic drug monitoring is essentially the only approach for the adjustment of immunosuppression in current practice, with suboptimal results. The implementation of immune monitoring strategies may contribute to minimizing the risk of adverse events attributable to over-immunosuppression without compromising graft outcomes.Areas covered: The present review (based on PubMed/MEDLINE searches from database inception to November 2019) is focused on immune biomarkers with no antigen specificity (non-pathogen-specific), including serum levels of immunoglobulins and complement factors, peripheral blood lymphocyte subpopulations, soluble CD30, intracellular ATP production by stimulated CD4⁺ T-cells, and other cell-based immune assays. We also summarized recent advances in the use of replication kinetics of latent viruses to assess the functionality of T-cell immunity, with focus on the nonpathogenic anelloviruses. Finally, the composite risk scores reported in the literature are critically discussed.Expert opinion: Notable efforts have been made to develop an enlarging repertoire of immune biomarkers and prediction models, although most of them still lack technical standardization and external validation. Preventive interventions based on these tools (prolongation of prophylaxis, tapering of immunosuppression, or immunoglobulin replacement therapy in hypogammaglobulinemic patients) remain to be defined, ideally in the context of controlled trials.

Clinical experience with a novel assay measuring cytomegalovirus (CMV)-specific CD4+ and CD8+ T-cell immunity by flow cytometry and intracellular cytokine staining to predict clinically significant CMV events

BACKGROUND

Cytomegalovirus (CMV) infection is one of the most common opportunistic infections following organ transplantation, despite administration of CMV prophylaxis. CMV-specific T-cell immunity (TCI) has been associated with reduced rates of CMV infection. We describe for the first time clinical experience using the CMV T-Cell Immunity Panel (CMV-TCIP), a commercially available assay which measures CMV-specific CD4+ and CD8+ T-cell responses, to predict clinically significant CMV events.

METHODS

Adult (> 18-year-old) patients with CMV-TCIP results and ≥ 1 subsequent assessment for CMV DNAemia were included at Brown University and the University of Maryland Medical Center-affiliated hospitals between 4/2017 and 5/2019. A clinically significant CMV event was defined as CMV DNAemia prompting initiation of treatment. We excluded indeterminate results, mostly due to background positivity, allogeneic hematopoetic cell transplant (HCT) recipients, or patients who were continued on antiviral therapy against CMV irrespective of the CMV-TCIP result, because ongoing antiviral therapy could prevent a CMV event.

RESULTS

We analyzed 44 samples from 37 patients: 31 were solid organ transplant recipients, 4 had hematologic malignancies, 2 had autoimmune disorders. The CMV-protection receiver operating characteristic (ROC) area under the curve (AUC) was significant for %CMV-specific CD4+ (AUC: 0.78, P < 0.001) and borderline for CD8+ (AUC: 0.66, P = 0.064) T-cells. At a cut-off value of 0.22% CMV-specific CD4+ T-cells, positive predictive value (PPV) for protection against CMV was 85% (95%CI 65-96%), and negative predictive value (NPV) was 67% (95%CI 41-87%).

CONCLUSIONS

The CMV-TCIP, in particular %CMV-specific CD4+ T-cells, showed good diagnostic performance to predict CMV events. The CMV-TCIP may be a useful test in clinical practice, and merits further validation in larger prospective studies.

The impact of recurrent cytomegalovirus infection on long-term survival in solid organ transplant recipients

BACKGROUND

Cytomegalovirus (CMV) remains a significant contributor to morbidity and mortality following solid organ transplantation (SOT). While recurrent infection occurs in up to 30% of patients, its impact on mortality is unclear. The aim of this study was to explore the relationship between recurrent CMV infection and long-term survival in SOT recipients.

METHODS

We performed a retrospective cohort study of SOT recipients who completed treatment for an episode of CMV infection. Patients were followed until death, loss to follow-up or 10 years following CMV treatment completion. Univariable and multivariable hazard ratios (HR) were calculated, treating relapse and rejection following CMV as time-varying.

RESULTS

About 79 kidney, 52 heart, 34 liver, and 5 liver-kidney transplant recipients were included. About 62/170 died, at a median of 3.8 years (IQR 0.8-6.6 years). Median follow-up among the 108 survivors was 7.4 years (IQR 3.7-10 years). Recurrent CMV infection occurred in 49/170 (29%), 67% within 6 months of treatment completion. Mortality among those who relapsed was 39% (19/49) vs 36% (43/121) in those who remained relapse-free (unadjusted HR 1.59, 95% CI 0.92-2.75, P = .10). After adjusting for age and transplanted organ, findings were similar (HR 1.68, 95% CI 0.93-3.04, P = .09).

CONCLUSIONS

Mortality following CMV remains high even in the valganciclovir era. Although our findings suggest a possible increased risk of death among patients with recurrent CMV, these did not reach statistical significance. The complex nature of these patients, multiple potential confounders, and limited statistical power made detection of small effects difficult. Larger prospective studies evaluating the clinical impact of strategies to reduce recurrence are needed.

Cytomegalovirus in solid organ transplant recipients-Guidelines of the American Society of Transplantation Infectious Diseases Community of Practice

Cytomegalovirus (CMV) is one of the most common opportunistic infections that affect the outcome of solid organ transplantation. This updated guideline from the American Society of Transplantation Infectious Diseases Community of Practice provides evidence-based and expert recommendations for screening, diagnosis, prevention, and treatment of CMV in solid organ transplant recipients. CMV serology to detect immunoglobulin G remains as the standard method for pretransplant screening of donors and transplant candidates. Antiviral prophylaxis and preemptive therapy are the mainstays of CMV prevention. The lack of a widely applicable viral load threshold for diagnosis and preemptive therapy is highlighted, as a result of variability of CMV nucleic acid testing, even in the contemporary era when calibrators are standardized. Valganciclovir and intravenous ganciclovir remain as drugs of choice for CMV management. Strategies for managing drug-resistant CMV infection are presented. There is an increasing use of CMV-specific cell-mediated immune assays to stratify the risk of CMV infection after solid organ transplantation, but their role in optimizing CMV prevention and treatment efforts has yet to be demonstrated. Specific issues related to pediatric transplant recipients are discussed.

Absolute Lymphocyte Count Thresholds: A Simple, Readily Available Tool to Predict the Risk of Cytomegalovirus Infection After Transplantation

This study of 64 solid organ and hematopoietic stem cell transplant recipients found that peripheral blood absolute lymphocyte count of <610 and <830/µL, respectively, correlated with cytomegalovirus infection. In an era when sophisticated measures of CMV-specific T cells are emerging, we emphasize the utility of the inexpensive and readily-available absolute lymphocyte count.