Monitoring of human cytomegalovirus-specific CD4 and CD8 T-cell immunity in patients receiving solid organ transplantation

Absolute and human cytomegalovirus (HCMV)-
specific CD4+ and CD8+ T-cell counts were monitored
in 38 solid organ (20 heart, 9 lung and 9 kidney)
transplant recipients during the first year after transplantation
by a novel assay based on T-cell stimulation
with HCMV-infected autologous dendritic cells. According
to the pattern of T-cell restoration occurring
either within the first month after transplantation
or later, patients were classified as either early (n =
21) or late responders (n = 17). HCMV-specific CD4+
and CD8+ T-cell counts were consistently lower in
late compared to early responders from baseline
through 6 months after transplantation. In addition,
in late responders, while HCMV infection preceded
immune restoration, HCMV-specific CD4+ restoration
was significantly delayed with respect to CD8+ T-cell
restoration. The number of HCMV-specific CD4+
and CD8+ T-cells detected prior to transplantation
significantly correlated with time to T-cell immunity
restoration, in that higher HCMV-specific T-cell counts
predicted earlier immune restoration. Clinically, the
great majority of early responders (18/21, 85.7%) underwent
self-resolving HCMV infections (p = 0.004),
whereas the great majority of late responders (13/17,
76.5%) were affected by HCMV infections requiring
antiviral treatment (p = <0.0001). Simultaneous
monitoring of HCMV infection and HCMV-specific
T-cell immunity predicts T-cell-mediated control of
HCMV infection.