Implementing CLIA for QuantiFERON®-CMV testing: Optimizing cellular immune response against cytomegalovirus.

INTRODUCTION

Cytomegalovirus (CMV) remains a significant infectious complication in solid organ transplant recipients. Assessing cellular immunity through interferon-gamma (IFN-γ) release assays, such as QuantiFERON®-CMV (QTF-CMV), is useful for guiding prophylactic and therapeutic decisions. Although ELISA is the validated method for QTF-CMV, chemiluminescence immunoassay (CLIA) may offer technical advantages. This study aimed to evaluate the performance of the CLIA-based LIAISON® QuantiFERON®-TB Gold Plus assay in quantifying IFN-γ in QTF-CMV testing, compared to the ELISA-based QuantiFERON®-CMV assay.

METHODS

A retrospective study was conducted on 169 stored plasma samples from 85 lung transplant recipients. IFN-γ was quantified using both ELISA (Qiagen®) and CLIA (DiaSorin®). Specific (CMV-NIL) and nonspecific (MIT-NIL) responses were compared using Pearson and Lin's concordance correlation coefficients, Bland-Altman analysis, and ROC curves. Diagnostic agreement was assessed using the Kappa index, sensitivity, specificity, and agreement rates.

RESULTS

CLIA yielded significantly higher IFN-γ values than ELISA for CMV-NIL (+0.41IU/mL) and MIT-NIL (+0.33IU/mL). Strong correlation and concordance were observed (r and ρc >0.93). Diagnostic agreement reached 95.86% (Kappa=0.913), with fewer indeterminate results in CLIA (3.55% vs 4.73%). The optimal CLIA cut-off was 0.2754IU/mL, achieving 100% sensitivity and specificity compared to ELISA.

CONCLUSIONS

CLIA shows excellent agreement with ELISA in QTF-CMV testing and is a reliable and automatable alternative. Its implementation may improve laboratory workflows. Adjusting the cut-off is recommended for optimal diagnostic accuracy.