S‐100 protein‐positive dendritic cells in colorectal adenocarcinomas. Distribution and relation to the clinical prognosis

Dendritic cells (DC) in 121 colorectal adenocarcinomas were investigated immunohistochemically, using anti‐S‐100 protein antibody. S‐100(+) DC were recognized among the malignant cells and/or around the tumor and differed in distribution either from lysozyme‐positive macrophages or from neuron‐specific enolase‐positive neural tissue. Patients with many S‐100(+) DC (more than 30 cells per 10 high‐power fields) in the tumor survived longer than did those with few such cells (less than 30 cells), most often with no metastases (P < 0.001). The grade of S‐100(+) DC infiltration was related to both density of lymphocytic infiltration in the primary tumor and the degree of paracortical hyperplasia in the regional lymph nodes (P < 0.05). Dendritic cells, therefore, as antigen‐presenting cells, conceivably mediate cell immunity in a tumor with lymphoid infiltration and in the regional lymph nodes. The number of S‐100(+) DC in the primary colorectal carcinomas represents one aspect of such a series of antitumor immunoreaction, in vivo.