Interplay of stromal tumor-infiltrating lymphocytes, normal colonic mucosa, cancer-associated fibroblasts, clinicopathological data and the immunoregulatory molecules of patients diagnosed with colorectal cancer.

A total of 94 patients with colorectal cancer (CRC) were included in this study. Lymphocytic infiltration of CD45 cells in the normal colon was more pronounced than that in the paired tumor stroma (p = 0.0008). The mean immunoscore of CD45TILs was decreased in CRC compared with the controls (p = 0.0010). The percentage of CD3 cells was higher in stage II than in stage IV (p = 0.0218) and showed a negative correlation with the TNM classification (r = -0.2867, p = 0.0109). The number of stromal CD4TILs was higher in stage I than in stage III (p = 0.0116) and IV (p = 0.0104), and there was a negative correlation between this number and the stage (r = -0.3708, p = 0.0008). There was a positive correlation between the Ki-67 and CD45 (r = 0.2468, p = 0.0294), CD3 (r = 0.3822, p = 0.0006), and CD4 cells (r = 0.5465, p < 0.0001). The levels of cancer-associated fibroblast (CAF) markers such as α-SMA, thrombin and fibronectin were significantly higher in CRC than in normal colonic mucosa. The immunohistochemical expression of α-SMA was negatively correlated with TILs, while fibronectin showed positive coexpression. A higher number of cells expressing IL-2Rα, PD-L1, CD33 and CD14 were found in colorectal adenocarcinomas than in controls. The number of CD14 cells was also dependent on the TNM stage (p = 0.0444) and tumor budding (p = 0.0324). These findings suggest a suppressive impact of CRC on the adaptive immune response and emphasize the importance of CAFs in regulating tumor immunity.