Comparison of two sialosyl-Tn binding monoclonal antibodies (MLS102 and B72.3) in detecting pancreatic cancer.

An immunohistochemical study has been carried out to compare and contrast the cellular distribution of two different sialosyl-Tn antigen binding monoclonal antibodies, MLS102 and B72.3, in the pancreas. MLS102 but not B72.3 monoclonal antibody binding increases with the content of the sialosyl-Tn epitopes. It was found that all 13 pancreatic cancer specimens bound both MLS102 and B72.3 monoclonal antibodies. Their cellular distribution in the cancer was virtually identical. Fifteen of 20 (75%) patients with chronic pancreatitis and five of 10 (50%) normal subjects were B72.3 positive, but MLS102 was completely negative in the latter group. Both monoclonal antibodies bound fetal pancreas diffusely. Thus, when pancreatic ductal cells have undergone malignant transformation, like the fetal pancreas, they express cell surface and secreted glycoconjugates with increased sialosyl-Tn epitopes suggesting enhanced 2-6 sialosyltransferase activity. This study shows that MLS102 is an extremely sensitive and specific tumour marker in the pancreas and that it is better than B72.3 in distinguishing pancreatic cancer from normal and chronic pancreatitis.