Figure 4. CD69 expression marks T cell compartmentalization in tissue sites.

(A) Representative flow cytometry histograms showing CD69 expression by CD4⁺ (top) and CD8⁺ (bottom) naïve (red), TCM (blue), TEM (black), and TEMRA (green) cell subsets from donor #101. (B) Mean frequency (+− SEM) of CD69⁺ CD4⁺ and CD8⁺ T naïve, TCM, TEM, and TEMRA cell subsets among blood, lymphoid and mucosal tissues. Data shown are compiled from 29 donors (Table S2). (C) Distribution variance of CD69⁺CD4⁺ (top) and CD8⁺ (bottom) naïve, TCM, TEM, and TEMRA subsets in blood, lymphoid and mucosal tissues from (B). (D) Spearman correlation analysis of changes in CD69⁺ subset tissue distribution with increasing age. Correlation strength and directionality (r=−1, left to r=+1, right) is shown for each tissue. Correlation significance for each tissue is denoted by shading (p<0.05, striped; p<0.01, gray; p<0.001, black; not significant, white). Individual r- and p-values are listed in Table S5) (E) Representative flow cytometry plots showing CD103/CD69 expression patterns by CD8⁺ TEM subsets in circulation, lymphoid, and mucosal tissues. Number in upper and lower right quadrants indicate %CD69⁺CD103⁺ and %CD69⁺CD103⁻ cells, respectively. (F) Overall distribution of TEM subpopulations delineated by CD69 and CD103 expression: CD69⁺CD103⁺, light gray; CD69⁺CD103⁻, blue; CD69⁻ CD103⁺, yellow; and CD69⁻ CD103⁻, dark gray. Graphs shows mean frequencies (±SEM) of these subsets among CD8⁺ TEM from nine tissues compiled from 10 donors with each tissue representing 5 or more donors. Individual donors used are indicated in Table S2.