Relationship between interleukin-12-expressing cells and antigen-presenting cells in patients with colorectal cancer

Interleukin-12 (IL-12) is a powerful cytokine that plays an important role in cell-mediated immunity. Although IL-12 is produced by antigen-presenting cells (APCs), the relationship between IL-12 expression and APCs in colorectal cancer tissue remains unknown.

Immunohistochemical detection of APCs and IL-12 was performed in 22 colorectal cancer specimens. CD83 and CD68 were used for the markers of mature dendritic cells (DCs) and macrophages, respectively. Double staining with CD83 or CD68 and IL-12 was also performed to detect IL-12-secreting cells. CD83-, CD68- and IL-12-positive-cell densities, clinicopathological factors and survival were analyzed.

CD83-, CD68- or IL-12-positive-cells were stained in the tumor stroma. Double-stained CD83/IL-12- or CD68/IL-12-positive-cells were also detected in the same area. The CD83-positive-cell density was significantly higher in patients with a high IL-12-positive-cell density than those with a low IL-12-positive-cell density. The CD83-positive-cell density was significantly lower in patients with T3-T4 depth of invasion, lymph node metastasis or tumors more advanced than stage II. The IL-12-positive-cell density tended to be lower in patients with T3-T4 depth of invasion or venous invasion. Patients with high CD83- or IL-12-positive-cell density in their cancer specimens showed significantly better prognosis.

This study provides new information on the significance of mature DCs, macrophages and IL-12-secreting cells in the local environment of colorectal cancer. Survival in patients with colorectal cancer was reflected by mature DCs and/or IL-12-positive-cell density.