CMV-specific CD8⁺ T cells in healthy CMV carriers are CCR7⁻ but can be either CD27⁺CD45RA⁻ memory cells or CD27⁻CD45RA⁺ effector cells.

Dot plots and photographs are from 2 healthy CMV-seropositive, HLA-A2⁺ individuals; left, donor L; right, donor B. (A) NLVPMVATV–HLA-A2.1 tetramer-APC fluorescence (“tetramer,” x-axis, arbitrary units, log scale) versus CD8-PerCP fluorescence (y-axis, arbitrary units) of lymphocytes gated on forward-scatter and side-scatter parameters. The quadrangles represent the gates for the analyses in panels B and C. Similar gates were used for the experiment represented in panel D. (B) Mouse anti-CCR7/goat anti–mouse-PE fluorescence (x-axis, arbitrary units, log scale) versus CD45RA-FITC fluorescence (y-axis, arbitrary units, log scale) within either gated CD8⁺ T cells (CD8⁺) or gated tetramer-positive CD8⁺ T cells (tetramer⁺). (C) CD27-PE fluorescence (x-axis, arbitrary units, log scale) versus CD45RA-FITC fluorescence (y-axis, arbitrary units, log scale) within either gated CD8⁺ T cells (CD8⁺) or gated tetramer-positive CD8⁺ T cells (tetramer⁺). (D) Dot plots gated on tetramer-positive CD8⁺ T cells from one donor with a predominant effector phenotype (left) and one donor with a memory phenotype (right). CD27-FITC fluorescence (y-axis) versus granzyme B–PE fluorescence (x-axis). (E) Frequencies of granzyme B–positive cells (▪, y-axis, percentage of tetramer-positive CD8⁺ T cells) from donors with an effector (left bar) or memory (right bar) phenotype.