Proportions of TIA-1⁺ subset of CD4⁺ T lymphocytes in CMV-seropositive and CMV-seronegative healthy adults. Box plots show median, interquartile range, and 10th and 90th percentiles for each cohort (error bars). The number of subjects in each subgroup is shown, and the P value was determined by Mann-Whitney nonparametric comparison of the 2 subgroups.