Relationship between multifunctional CMV-specific CD8⁺ T cell levels, CMV reactivation, and donor CMV status. (A) The 8 combinations of T cells positive or negative for TNF-α, CD107, and MIP are shown as a percentage of IFN-γ–CD8⁺ T cells and subdivided according to donor CMV status. Each circle represents a single measurement, and samples from all 3 time points are pooled for display. The vertical scale uses square-root spacing, labeled with percentages. Boxes cover the central 50% of the observations, with a central bar at the median. Significance probabilities (P), shown for each subset are from a 2-sided rank-sum test after reducing the data to a single mean per subject. (B) The percentages of 4-functional CD8⁺ T cells from D⁺/R⁺ and D⁻/R⁺ recipients were further divided according to CMV reactivation status as defined by PCR. There was no statistically significant time trend, so samples from 3 time points were pooled for display from day 90, day 180, and day 360 observations. Each dot represents an individual measurement. Boxes cover the central 50% of the observations, with a central bar at the median. Nomenclature for patients and CMV reactivation defined in Figure 2 legend. The P values are from rank-sum tests on the pre- or postreactivation subsets, using one mean value for each subject, and are not adjusted. Using all data and adjusting for covariates, recipients with D⁻ donors have significantly lower average 4-function T cell levels (P = .01, Table 5).