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.