Expression patterns of TILs, CAFs, and CD200 in PDAC patients. (A) TIL markers (CD4, CD8, and CD20) were characterized utilizing multiplexed fluorescence staining, with CD4 represented in white, CD8 in red, and CD20 in yellow. CAF markers (Thy-1, FAP, and SMA) were characterized with the same staining procedure, where FAP is represented in white, SMA is shown in red, and Thy-1 is in yellow. Representative images of stromal masks are depicted as well. (B) Dynamic range charts for TIL and CAF proteins in the stromal compartment of tumors in YTMA454. (C) CD200 was stained with a multiplex fluorescence staining protocol as well and is represented in red, alongside representative images of tumor and stromal masks. (D) Dynamic range of CD200 in both the tumor and stromal compartments of patients, with red lines depicting the visually determined thresholds for assay limit of detection. Abbreviations: DAPI, 4,6-diamidino-2-phenylindole; CK, cytokeratin; QIF, quantitative immunofluorescence.