We studied the correlation between the expression of HLA-DR antigen in primary colorectal adenocarcinoma and that in synchronous hepatic metastatic tumor.5 cases treated in our hospital without preoperative treatment such as chemotherapy or radiation were examined as the subject of the study. Tissue specimens were fixed in 10% neutrally buffer formalin solution, embedded in paraffin and stained with HLA-DR using the indirect immunoperoxidase technique. We classified the expression of HLA-DR antigen into 4 gradings, according to its intracellular staining pattern and the percentage of positive cancer cells in carcioma tissne. The following results were obtained. The expression of HLA-DR antigen in both primary colorectal adenocarcinoma and hepatic metastatic tumor was much lower than that in other colorectal adenocarcinoma. Also HLA-DR staining grade of each hepatic metastatic tumor was similar to that of primary colorectal adenocarcinoma. From these results, we speculated that HLA-DR antigen on cancer cells is correlated with their metastatic potentiality in colorectal carcinoma tissue.
