Clinical Assessment of Anti-Viral CD8+ T Cell Immune Monitoring Using QuantiFERON-CMV® Assay to Identify High Risk Allogeneic Hematopoietic Stem Cell Transplant Patients with CMV Infection Complications

Abstract

The reconstitution of anti-viral cellular immunity following hematopoietic stem cell transplantation (HSCT) is crucial in preventing cytomegalovirus (CMV)-associated complications. Thus immunological monitoring has emerged as an important tool to better target pre-emptive anti-viral therapies. However, traditional laboratory-based assays are too cumbersome and complicated to implement in a clinical setting. Here we conducted a prospective study of a new whole blood assay (referred to as QuantiFERON-CMV®) to determine the clinical utility of measuring CMV-specific CD8+ T-cell responses as a prognostic tool. Forty-one evaluable allogeneic HSCT recipients underwent weekly immunological monitoring from day 21 post-transplant and of these 21 (51.2%) showed CMV reactivation and 29 (70.7%) developed acute graft-versus-host disease (GvHD). Patients with acute GvHD (grade≥2) within 6 weeks of transplant showed delayed reconstitution of CMV-specific T-cell immunity (p = 0.013) and a higher risk of CMV viremia (p = 0.026). The median time to stable CMV-specific immune reconstitution was 59 days and the incidence of CMV reactivation was lower in patients who developed this than those who did not (27% versus 65%; p = 0.031). Furthermore, a failure to reconstitute CMV-specific immunity soon after the onset of CMV viraemia was associated with higher peak viral loads (5685 copies/ml versus 875 copies/ml; p = 0.002). Hence, QuantiFERON-CMV® testing in the week following CMV viremia can be useful in identifying HSCT recipients at risk of complicated reactivation.

Post transplant CMV-specific T-cell immune reconstitution in the absence of global T-cell immunity is associated with a high risk of subsequent virus reactivation

“…We recently reported the results of a prospective study where weekly CMV-specific immune monitoring was performed using a whole-blood functional assay, QuantiFERON-CMV (Cellestis, Carnegie, VIC, Australia), 8 which measures IFN-γ secretion in 1 mL of whole blood in response to 23 CMV peptide epitopes representing diverse MHC class I alleles. 9 This assay incorporates a phytohaemagglutinin-treated sample, which measures mitogen response and serves as a positive assay control.…”

“…In allo-HSCT, where patients are often lymphopenic or have impaired lymphocyte function, the mitogen response correlates with lymphocyte count. 8 Although IFN-γ secretion alone does not capture all T-cell activity, the mitogen response provides some indication of global T-cell response as a context for CMV-specific immune reconstitution. Here, we present additional analysis on our previously published study 8 and show that CMV-specific immune reconstitution follows two patterns, which are distinguishable by their concordance or otherwise with mitogen response and these two patterns are associated with divergent risks for CMV reactivation.…”

“…8 Briefly, patients undergoing allo-HSCT at the Royal Brisbane and Women's Hospital, Australia, were prospectively enrolled. Either the donor or the recipient or both must be CMV seropositive.…”

Modification of the HCMV-specific IFN-γ release test (QuantiFERON-CMV) and a novel proposal for its application

“…After culturing overnight, the supernatants are harvested and analyzed by ELISA for interferon -γ (IFN -γ) secreted from the T cells 18) . This kit has been approved as CE Marked for commercial use in Europe and has been applied to several clinical studies 18,19,20,21,22) , although it is not yet US FDA -approved. This method appears to afford advantages as a clinical test in terms of cost, sensitivity and ease of use.…”

Coinfection with Human Cytomegalovirus Genetic Variants in Transplant Recipients and Its Impact on Antiviral T Cell Immune Reconstitution

“…Current therapeutic strategies to control CMV reactivation in HSCT recipients predominantly involve the preemptive administration of ganciclovir to control CMV following detection of viral reactivation (6). Through the use of immunological monitoring approaches, it is becoming apparent that the prevention of viral reactivation and the long-term control of CMV infection are dependent upon the induction of robust and stable CMV-specific immunological memory (7)(8)(9)(10).…”