Significance of 2-3 and 2-6 sialylation of Lewis a antigen in pancreas cancer.

Distributions of sialylated derivatives of Lewis a (Lea) antigen in cancer tissue of the human pancreas and in the sera of patients with pancreas diseases have been studied; the significance of 2-3 and 2-6 sialylation of Lea antigens in pancreas cancer have been investigated using specific monoclonal antibodies. In most pancreas cancer tissue the 2-3 sialylated Lea antigen was found to be specifically distributed in cancer cells as determined by immunohistologic techniques, while a significantly smaller amount of the antigen was detected in surrounding nonmalignant pancreas tissue, which was infiltrated by cancer cells. Conversely, the 2-6 sialylated Lea antigen was abundantly present in nonmalignant pancreas tissue, while it was less frequently present in pancreas cancer cells. When the sera of 66 patients with pancreas diseases were examined for these sialylated Lea antigens, correlation studies showed that the levels of 2-3 sialylated Lea tended to be 44.1 times more than the levels of 2-6 sialylated Lea in the sera of cancer patients. The average ratio of 2-3 sialylated Lea to 2-6 sialylated Lea was 0.23 in the sera of patients with pancreatitis. These data collectively indicate that the 2-3 sialylation of Lea is remarkably enhanced, and the 2-6 sialylation of Lea antigen is suppressed in pancreas cancer. The determination of the 2-3 sialylated Lea to 2-6 sialylated Lea ratio in patients with pancreas diseases may be helpful for the differential diagnosis of pancreas cancer and nonmalignant pancreatic disorders.