Evaluation of the VIDAS Cytomegalovirus (CMV)-IGRA for Assessing CMV-Specific T-Cell Responses in Immunocompetent and Immunosuppressed Individuals.

We compared the performance of the VIDAS Cytomegalovirus (CMV)-Interferon-gamma release assay (IGRA) with that of laboratory-developed flow cytometry for intracellular cytokine staining (FC-ICS) for the assessment of CMV-specific interferon-gamma (IFN-γ)-producing T-cell responses (CMV-CMI). A total of 147 blood specimens from 78 adult participants were collected: 11 healthy controls, 34 hematological patients (HP), of which 32 had undergone allogeneic hematopoietic cell transplantation (allo-HCT), and 33 Kidney transplant recipients. Of the 147 specimens, 96 tested positive, 24 negative, 25 indeterminate, and 2 were invalid by the VIDAS CMV IGRA. A total of 137 specimens were tested by FC-ICS, of which 107 returned positive results. There were 27 discrepancies across the assays among specimens yielding interpretable results, of which 14 tested VIDAS CMV IGRA-positive/FC-ICS-negative and 12 VIDAS CMV IGRA-negative/FC-ICS-positive. The overall agreement between immunoassays was 78%, and the Kappa coefficient was 0.34 (0.52 for HP). Differences in identifying CMV-infected (CMV IgG-positive) and uninfected participants (CMV IgG-negative) were noticed across both assays. The overall correlation (rho values) between IFN-γ concentrations (IU/ml) measured by the VIDAS CMV IGRA and CMV-specific IFN-γ-producing T-cell frequencies were 0.27 for CD4+ and 0.33 for CD8+ T cells (p = 0.001). In HP, the correlation was stronger (0.48 for CD4+ and 0.49 for CD8+ T cells). In summary, our data lend support to the potential utility of the VIDAS CMV IGRA to assess CMV-CMI in transplant recipients.