Monitoring cell‐mediated immunity during immunosuppression reduction in heart transplant recipients with severe systemic infections

Background Treatment for severe systemic infections in heart transplantation is reduction in immunosuppression while treating the infection. An assay that measures adenosine triphosphate production in activated lymphocytes (ImmuKnow®) objectively monitors cellular immunity of transplant recipients. In this study, we used ImmuKnow® to adjust immunosuppression in heart transplant recipients with severe systemic infections. Methods Heart transplant recipients were followed with ImmuKnow® at the time of biopsy and diagnosis of systemic infection. Patients who developed an infection were monitored by ImmuKnow® assay with adjustments in immunosuppression based upon the results of the assay. Maintenance immunosuppression was reinstituted when the ImmuKnow® increased to >225 ng/mL of ATP. Results Two or more ImmuKnow® assays were performed in 80 patients. Thirteen patients developed severe systemic infections. ImmuKnow® mean value at the time of diagnosis of infection was 109 ± 49.2 ng/mL. Reduction in immunosuppression and treatment of infection resulted in normalization of ImmuKnow® level, resolution of infection, and no episodes of rebound rejection. Conclusion Heart transplant recipients with severe systemic infections presented with a decreased ImmuKnow®, suggesting over immunosuppression. ImmuKnow® can be used as an objective measurement in withdrawing immunosuppression in heart transplant recipients with severe systemic infections.