Fig. 1

Immunohistochemical analysis of C4BPA, CD40, and CD8 expression in resected human PDAC samples. a C4BPA staining patterns in primary PDAC tissues (n=171) were categorized into high (left) and low stromal C4BPA expression (right) based on the intensity criterion. The boxed area is magnified in the lower panel. Original magnification: upper panels ×40, lower panels ×200. b Kaplan-Meier analyses for DFS and OS of PDAC patients based on stromal C4BPA expression. The high stromal C4BPA group presented significantly longer DFS (P=0.0053, log-rank test) and OS (P=0.0012, log-rank test) than did the low stromal C4BPA group after curative surgery. c CD40 staining patterns in primary PDAC tissue were categorized into high (left) and low stromal CD40 expression (right). Original magnification: ×40. d Correlation of C4BPA and CD40 expression in the stroma of human PDAC tissues. e Kaplan-Meier analyses for OS of PDAC patients based on stromal C4BPA and CD40 expression. Patients with high stromal C4BPA and CD40 presented significantly longer OS (P=0.0005, log-rank test) than did other patients. f CD8⁺ T cell staining patterns in primary PDAC tissue were categorized into high (left) or low CD8⁺ expression (right). Original magnification: ×40. g Correlation of C4BPA and CD8 expression in stroma of human PDAC tissues (P=0.001, Mann–Whitney–Wilcoxon test). h Kaplan-Meier analyses for OS of PDAC patients based on CD8 expression. Patients with high stromal C4BPA/CD8⁺ presented significantly longer OS (P=0.0005, log-rank test) than did other patients. i–m Immunofluorescence analysis of CD8⁺ TILs in human PDAC tissues. i H&E staining and (j–m) quadruple immunofluorescence staining for C4BPA (green), CD40 (red), CD8 (white), and DAPI (blue). Boxed regions highlight regions where stromal C4BPA is coexpressed with CD40 and CD8 in the TME of primary PDAC tissues. Yellow arrows indicate areas where enrichment of stromal CD8⁺ cells expressing C4BPA was observed. Magnification: ×100 for c and f. Bar, 50 μm. P-values are indicated in the respective tables. ns, not significant.