Immunohistochemically demonstrated expression of HLA-DR antigen in colorectal adenocarcinomas and its relation to clinicopathological features

We studied 148 colorectal adenocarcinomas to clarify any correlation between HLA‐DR antigen expression on tumor cells and histopathological features. Paraffin sections of formalin‐fixed tissues were stained with HLA‐DR antigen using the indirect immunoperoxidase technique. All the tumor tissues were divided into two groups, depending on the incidence of HLA‐DR‐positive cells (greater and lesser than 50%). Carcinoma tissues with a higher incidence showed less mural invasion, lymphoductal invasion, venous invasion, lymphonodular metastasis, and peritoneal metastasis. Tissues with a high HLA‐DR reactivity were more often observed for Dukes' A and B stages, whereas those with a low HLA‐DR positivity were frequently Dukes' C and D stages. As for the cumulative survival rate, the group with high HLA‐DR expression demonstrated significantly better survival. We speculate that HLA‐DR expression by colorectal cancer cells exerts a favorable influence on clinical course.