HLA class I antigen expression in human solid tumors

The expression of HLA class I antigens was studied by immunohistochemistry in various tumors in correlation with clinicopathologic characteristics. Reduced expression was observed in germ cell testicular cancer, kidney, prostate, gastric and colon cancer, and was associated with tumor aggressiveness, grade and penetration of the tumor through the organ wall. In bladder cancer reduced expression was associated with poor survival. Irradiation of brain tumors resulted in an increase in class I expression. Soluble class I levels were studied in breast and colon cancer patients and were found to be high in those with metastatic disease. The clinical relevance of reduced class I levels are discussed.