Figure 2. Diverse multifunctional CMV-specific CD4⁺T cell effector memory populations are significantly increased in the lung during chronic infection but not among CD8⁺T cells.

Representative multifunctional flow cytometric plots of (A) CD4⁺ and (B) CD8⁺ T cell LMNC and PBMC following restimulation with CMV antigen in two LTRs showing the frequency of IFN-γ by TNF-α, MIP-1 β and IL-2 as well as TNF-α by IL-2 during chronic infection. Individual pie charts show the percentage of pp65-specific CD4⁺ (C) and CD8⁺ (D) T cells that produce 1, 2, 3 or 4 functional responses. CMV-specific CD4⁺ multifunctional responses to pp65-pooled peptides were significantly more frequent in the lung allograft than peripheral blood (p < 0.05) (C), while CD8⁺ multifunctional responses were equally distributed between the two compartments (D). Using Boolean analysis, the percentage of total for individual multifunctional subset responses for LMNC (blue bars) and PBMC (red bars) are shown in the bar graph for each of the 15 multifunctional subsets. Significant differences when comparing frequencies (mean ± SEM, not shown) of LMNC and PBMC pp65-specific single and multifunctional responses are indicated by a *p < 0.05, **p < 0.01 and ***p < 0.001. Figures represent results from 8 LTRs. All p-values were determined by the Kruskal–Wallis one-way ANOVA or Wilcoxon signed-rank test.