Clinical validation of a novel enzyme-linked immunosorbent spot assay-basedin vitrodiagnostic assay to monitor cytomegalovirus-specific cell-mediated immunity in kidney transplant recipients: a multicenter, longitudinal, prospective, observational study

Abstract

Impaired cytomegalovirus (CMV)-specific cell-mediated immunity (CMV-CMI) is a major cause of CMV reactivation and associated complications in solid-organ transplantation. Reliably assessing CMV-CMI is desirable to individually adjust antiviral and immunosuppressive therapy. This study aimed to evaluate the suitability of T-Track CMV, a novel IFN-γ ELISpot assay based on the stimulation of peripheral blood mononuclear cells with pp65 and IE-I CMV proteins, to monitor CMV-CMI following kidney transplantation. A prospective longitudinal multicenter study was conducted in 86 intermediate-risk renal transplant recipients. CMV-CMI, CMV viral load, and clinical complications were monitored over 6 months post-transplantation. Ninety-five percent and 88-92% ELISpot assays were positive pre- and post-transplantation, respectively. CMV-specific response was reduced following immunosuppressive treatment and increased in patients with graft rejection, indicating the ability of the ELISpot assay to monitor patients' immunosuppressive state. Interestingly, median pp65-specific response was ninefold higher in patients with self-clearing viral load compared to antivirally treated patients prior to first viral load detection (P < 0.001), suggesting that reactivity to pp65 represents a potential immunocompetence marker. Altogether, T-Track CMV is a highly sensitive IFN-γ ELISpot assay, suitable for the immunomonitoring of CMV-seropositive renal transplant recipients, and with a potential use for the risk assessment of CMV-related clinical complications (ClinicalTrials.gov Identifier: NCT02083042).

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

“…A diagnostic test of immune competency against CMV can be utilized in different scenarios: at the end of primary prophylaxis, to determine if extended prophylaxis or close VL monitoring might be of benefit [10-16, 18, 22, 25]; at the end of treatment of CMV infection, to support the need for secondary prophylaxis [6,8]; finally, in patients with asymptomatic CMV DNAemia, to determine if antiviral treatment is truly indicated [12,13,17,23,29]. Herein, the CMV-TCIP performed well in a relatively small (but comparable in size to other similar studies [8,12,29,30]) case series, including all three potential scenaria.…”

“…The Quantiferon®-CMV assay can predict late-onset CMV disease after primary prophylaxis [10][11][12][13][14][15][16] and spontaneous clearance of CMV DNAemia [12,13,29]; it has also been used in two interventional studies to guide primary [16] or secondary (after treatment for a CMV event) [8] prophylaxis. ELISPOT-based CMV-CMI assays (T-Track CMV® and T-SPOT®-CMV) can also help predict CMV events [17][18][19][20][21][22][23][24][25][26]. It should be noted though that, at the time of this manuscript, these assays are limited to research use only in the US.…”

“…Interferon gamma (IFN-γ) released from activated CD8+ T-cells is then quantified via ELISA, allowing for a measure of CMV-specific CD8+ (but not CD4+) T-cell response [8][9][10][11][12][13][14][15][16]. The T-Track CMV® and T-SPOT®-CMV assays first isolate peripheral blood mononuclear cells (PBMC), then expose them to a variety of CMV antigens or lysates; the resulting IFN-γ is quantified via ELISpot allowing for a measure of aggregate CMV-specific CD4+/CD8+ Tcell and NK-cell response, but not its individual components [17][18][19][20][21][22][23][24][25][26]. None of these assays are commercially available in the United States (US).…”

Results of Questionnaire Survey of Current Immune Monitoring Practice of Transplant Clinicians and Clinical Pathologists in Korea: Basis for Establishment of Harmonized Immune Monitoring Guidelines

“…There are active clinical trials for investigating the clinical utility of IGRA for cytomegalovirus (CMV) infection which measuring CMV-specific immunity in host (36). The assays to estimate the degree of adverse immunosuppression or immune activation potentially against allograft have been …”

Virus-specific T cells in pediatric renal transplantation

“…There are two easy to apply assays which are commercially available for measuring the cellular response to CMV viremia but they do not directly determine the number of virus-specific T cells: QuantiFERON CMV, which is a whole blood interferon-gamma release assay based on ELISA technology [22] and T-Track CMV, which is an ELISpot assay [23]. Both assays have been used in initial diagnostic trials to determine diagnostic cutoff values [24,25]. These assays are simple to use but both have the limitation that they only give a rough estimation of T cell activation.…”