Utility of the Enzyme-Linked Immunospot Interferon-γ-Release Assay to Predict the Risk of Cytomegalovirus Infection in Hematopoietic Cell Transplant Recipients

Abstract

The ability to distinguish allogeneic hematopoietic cell transplant (allo-HCT) recipients at risk for cytomegalovirus (CMV) reactivation from those who are not is central for optimal CMV management strategies. Interferon γ (IFN-γ) produced by CMV-challenged T cells may serve as an immune marker differentiating these 2 populations. We prospectively monitored 63 CMV-seropositive allo-HCT recipients with a CMV-specific enzyme-linked immunospot (ELISPOT) assay and for CMV infection from the period before transplantation to day 100 after transplantation. Assay results above certain thresholds (50 spots per 250 000 cells for immediate early 1 or 100 spots per 250 000 cells for phosphoprotein 65) identified patients who were protected against CMV infection as long as they had no graft-versus-host disease and/or were not receiving systemic corticosteroids. Based on the multivariable Cox proportional hazards regression model, the only significant factor for preventing CMV reactivation was a CMV-specific ELISPOT response above the determined thresholds (adjusted hazard ratio, 0.21; 95% confidence interval, .05-.97; P = .046). Use of this assay as an additional tool for managing allo-HCT recipients at risk for CMV reactivation needs further validation in future studies. Application of this new approach may reduce the duration and intensity of CMV monitoring and the duration of prophylaxis or treatment with antiviral agents in those who have achieved CMV-specific immune reconstitution.

Keywords: ELISPOT; IGRA; bone marrow transplant; cytomegalovirus; stem cell transplant.

Figure 1.

Scatterplot for cytomegalovirus (CMV) reactivation versus the number of spots produced in the CMV-specific enzyme-linked immunospot assay for phosphoprotein 65 antigen at various time points. The reference line at 100 spot counts denotes the study-specific threshold, which awaits confirmation by future studies. Abbreviation: HCT, hematopoietic cell transplantation.

Figure 2.

Kaplan–Meier failure curves of the time to significant cytomegalovirus (CMV) reactivation, stratified by high and low response to the CMV-specific enzyme-linked immunospot assay. Abbreviation: HCT, hematopoietic cell transplantation.

Figure 3.

Use of cytomegalovirus (CMV)–specific enzyme-linked immunospot assay for developing an immune monitoring approach in allogeneic hematopoietic cell transplant (allo-HCT) recipients. Abbreviations: GvHD, graft-versus-host disease; PCR, polymerase chain reaction.