CMV-specific T-cell immunity in solid organ transplant recipients at low risk of CMV infection. Chronology and applicability in preemptive therapy.

OBJECTIVES

To characterize whether the CMV-specific cellular immune response can be used as a predictor of the control of CMV infection and disease and determine thresholds in solid organ transplant (SOT) recipients seropositive for CMV (R+).

METHODS

The CMV-specific T-cell response was characterized using intracellular cytokine staining and the evolution of clinical and virological parameters were recorded during the first year after transplantation.

RESULTS

Besides having positive CMV serology, only 28.4% patients had positive immunity (CD8+CD69+IFN-γ+ ≥0.25%) at 2 weeks after transplantation. These patients had less indication of preemptive treatment (p = 0.025) and developed less high grade (≥2000 IU/ml) CMV replication episodes (p = 0.006) than patients with no immunity. Of the 49 patients with a pretransplant sample, only 22.4% had positive immunity, and had a detectable immune response early after transplantation (median of 3.7 weeks). However, only 50% of patients with negative pretransplant immunity acquired a positive immune response and it was significantly later, at a median of 11 weeks (p < 0.001). Patients that developed CMV disease had no CMV-specific immunity.

CONCLUSIONS

Having CMV-specific CD8+IFN-γ+ cells ≥0.25% before transplant; 0.15% at two weeks or 0.25% at four weeks after transplantation, identifies patients that may spontaneously control CMV infection and may require less monitoring.