Infiltration of CD14-positive macrophages at the invasive front indicates a favorable prognosis in colorectal cancer patients with lymph node metastasis

Background/Aims: To clarify the distribution of CD14⁺ macrophages in colorectal cancer using flow cytometry and immunohistochemistry, and to elucidate the roles of CD14⁺ macrophages in colorectal cancer. Methodology: We studied the paired cancerous and corresponding normal tissues from 52 patients with colorectal cancer for the distribution of CD14 ⁺, CD1a⁺, CD83⁺ and CD68⁺ cells, and correlated the findings with the clinicopathological characteristics and with the expression of CD86 and CD80 in the CD14⁺ macrophages, which are co-stimulatory factors for T cell activation. Results: 1) CD14⁺ macrophages were distributed predominantly at the invasive front of colorectal cancer tissues, rather than in the normal tissues, 2) a high percentage of the CD14⁺ macrophages expressed CD86 and CD80, and 3) in the colorectal cancer cases with lymph node metastasis, the 5-year overall survival rate of the high CD14 group, in which the number of CD14⁺ macrophages was higher than the median, was better than that of the low CD14 group. Conclusion: The infiltration of CD14⁺ macrophages at the invasive front indicates a favorable prognosis in colorectal cancer patients with lymph node metastasis. In addition, the activation of CD14⁺ macrophages and T cells may facilitate the development of new immunotherapeutic strategies for colorectal cancer patients.