Figure 4.

Plasmacytoid dendritic cells (pDCs) colocalize preferentially with CD8⁺ T cells. (A) Representative example of a tissue region from a whole slide stained with a seven-color multiplex immunofluorescence protocol. Samples were automatically segmented and phenotyped based on their fluorescence staining. (B, C) Localization of pDCs (red) and CD8⁺ T cells (orange) or FoxP3⁺CD4⁺ Tregs (purple) are illustrated. The white line indicates a distance ≤25 µm from a pDC to their closest T cell. (D) Cumulative distribution of the closest distance for pDCs to CD8⁺ T cells (black line) is shown in comparison to a theoretical distribution based on a Poisson distribution with its confidence envelope (red line, gray area). (E) Boxplot illustrating the averaged fraction of pDCs in close distance to a CD8⁺ T cell or a FoxP3⁺CD4⁺ Treg, respectively, based on 47 colon cancer tissue samples. Asterisks indicate a statistically significant difference (****p≤0.0001). (F) Kaplan-Meier curves demonstrate the correlation between the fraction of pDCs neighboring a CD8⁺ T cell and overall survival of patients with colon cancer. Significance was assessed using the log-rank test.