Background: Dendritic cells (DC), including epidermal Langerhans cells, are potent antigen-presenting cells that can carry and present tumor antigens to helper T-cells. An immunohistochemical study was performed to clarify the relationship between the extent of infiltration by DCs in primary gastric cancer and that in the regional lymph nodes.
Methods: Paraffin blocks were prepared for staining with antibody against S-100 protein in 121 cases of gastric cancer. Infiltration of S-100 protein-positive DCs was evaluated in the primary tumor and in the peritumoral, primary, secondary, and tertiary nodes.
Results: The extent of infiltration by DCs into the regional lymph nodes decreased significantly with an increasing distance of the nodes from the primary tumor. Correlation of the extent of such infiltration was observed among the peritumoral, primary, secondary, and tertiary nodes. However, the extent of infiltration into the primary tumor did not correlate with that into the primary, secondary, and tertiary nodes. Infiltration by DCs of the peritumoral nodes correlated with that of the tumor, particularly when lymph node metastasis was absent. There was no significant difference in the extent of infiltration into the peritumoral nodes even when lymph nodes were involved. However, infiltration of DCs increased in the primary and secondary nodes when the primary nodes were involved.
Conclusion: Infiltration of DCs may be regulated in the primary lesion of gastric cancer. The peritumoral lymph nodes serve as transmitters of DCs from the primary tumor to the regional lymph nodes. DCs in the regional lymph nodes are important for establishing immunologic defense mechanisms in cases of gastric cancer when metastasis is absent or limited to the primary nodes.