Macrophages (Mφs) constitute a major component of the leukocyte infiltrate and perform distinct roles in different tumor microenvironments. This study aimed to characterize the distribution, composition and prognostic value of Mφs in hepatocellular carcinoma (HCC) and gastric cancer (GC). Immunohistochemistry and immunofluorescence were used to identify Mφ subsets in HCC and GC tissues. Kaplan–Meier analysis and Cox regression models were applied to estimate the overall survival (OS) for HCC and GC patients. The results showed that the density of Mφs decreased in the intra-tumor region (IT) of HCC, but remarkably increased in the IT of GC, as compared with their non-tumor regions (NT). In HCC, most CD68+ Mφs were CD204+ and CD169+ cells in the NT region; however, there was a significant decrease in the percentage of CD169+ Mφ in the IT region. In contrast, CD68+ Mφs comprised a smaller percentage of CD204+ than the CD169+ subpopulation in the NT region, while more CD204+ but fewer CD169+ cells were present in the IT region of GC. The density of CD204+ Mφs correlated with poor prognosis in HCC, and CD169+ Mφs were associated with good survival in both HCC and GC. Moreover, the combination of low numbers of CD204+ and high numbers of CD169+ Mφs was associated with improved OS in both GC and HCC. Mφs display tissue-specific distributions and distinct composition patterns in HCC and GC tissues. Our results suggested that different types of tumors might use diverse strategies to reconstitute Mφ patterns to promote tumor progression.

Background: A comprehensive investigation into immune cell infiltration provides more accurate and reliable prognostic information for patients with colorectal liver oligometastases (CLO) after liver metastasectomy. Methods: Simultaneous detection of the immune constituents CD3⁺, CD8⁺, Foxp3⁺ T, and α-SMA⁺ cells in the liver oligometastasis of 133 patients was conducted using a four-colour immunohistochemical multiplex technique. Immune cells were quantified, and tumour-infiltrating lymphocyte (TIL) ratios were subsequently calculated. Correlation analysis was performed using Pearson’s correlation. Recurrence-free survival (RFS) and overall survival (OS) for TIL ratios were analysed using the Kaplan–Meier method and Cox regression models. Results: Significantly fewer CD3⁺, CD8⁺, and Foxp3⁺ T cells were observed in the intratumoural region than in the peritumoural region of liver metastases. CD3⁺, CD8⁺, Foxp3⁺ T, and α-SMA⁺ cells showed significantly positive correlations with each other both in the intratumoural and peritumoural regions of liver metastases. Only the CD8/CD3 TIL ratio demonstrated a positive correlation between intratumoural and peritumoural regions of liver metastases (r = 0.541, p < 0.001). Patients with high intratumoural CD8/CD3 ratios had significantly longer 3-year RFS (59.0% vs. 47.4%, p = 0.035) and 3-year OS rates (83.3% vs. 65.8%, p = 0.007) than those with low intratumoural CD8/CD3 ratios. Multivariate analyses revealed that the intratumoural CD8/CD3 ratio was independently associated with RFS (HR = 0.593; 95% CI = 0.357–0.985; p = 0.043) and OS (HR = 0.391; 95% CI = 0.193–0.794; p = 0.009). Conclusion: These findings offer a better understanding of the prognostic value of immune cell infiltration on liver oligometastasis from colorectal cancer.