Viral antigen drives CD27 down-modulation on antigen-specific CD8⁺ T cells.

(A) Dot plots of CD27 expression (x-axis, arbitrary units, log scale) versus CD45RA expression (y-axis, arbitrary units, log scale) within gated tetramer-positive CD8⁺ T cells before transplantation (0M) and 12 months after transplantation (12M) from one patient without positive urine cultures (left panel) and one patient with positive urine cultures (right panel). (B) Frequencies of CD27⁻cells among CMV-specific CD8⁺ T cells (y-axis, percentage of tetramer-positive CD8⁺ T cells) in CMV-seropositive HLA-A2⁺ renal transplant recipients (designated by capitals) before and 12 months after transplantation (x-axis, months).