The partial characterization and clinical evaluation of pancreas cancer-associated antigen from the ascites fluid of a patient with pancreatic cancer.

Monoclonal antibodies against pancreas cancer-associated antigen (PCAAp) were produced by established hybridoma cells. Two monoclonal antibodies, 3F1 and 3B6, were selected and these two monoclonal antibodies were found immunohistologically to react strongly with cancer cells and intraductal mucin-like products in well-differentiated pancreatic cancer tissues, but weakly, if at all, with gastric, colorectal and other cancers and at all not with normal adult or fetal pancreatic tissue. PCAAp is usually expressed in normal colonic mucosa (PCAAc), but the two monoclonal antibodies scarcely reacted with normal colonic mucosa. A sandwich enzyme immunoassay was developed to measure circulating PCAAp. Thirty-two normal subjects and 271 patients comprised of 210 with malignant disease and 61 with benign disease were surveyed. The cut-off value of PCAAp levels in the 32 normal subjects was 2.06 micrograms/ml, being the mean + 2SD, while PCAAp levels of more than this were observed in 72 per cent of the patients with pancreatic cancers, 65 per cent of those with bile duct cancers, 60 per cent of those with hepatomas, 0-30 per cent of those with other malignant diseases, and 10 per cent of those with benign hepatobiliary diseases. The susceptibility of isolated PCAAp and PCAAc to various enzymes and chemical reagents were also studied. The results of this study suggest that the assay for PCAAp might be useful in the diagnosis of pancreatic cancer.