Development of serological diagnosis of pancreatic cancer for mass screening

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Two different types of gamma-glutamyltranspeptidase (gamma-GTP) have been found in normal human pancreas following bromelain treatment. On the other hand, three human pancreatic ductal cell carcinomas have only a single type of gamma-GTP upon analysis with polyacrylamide gel electrophoresis, anion-exchange column chromatography and isoelectric focusing. Carcinoma gamma-GTPs were almost identical to one of the two types of normal pancreatic gamma-GTPs. The gamma-GTP from pancreatic carcinomas bound to anion-exchange column and was eluted at the same Nacl fractions as normal pancreatic gamma-GTP. The properties of pancreatic carcinoma gamma-GTP, as assessed by binding to concanavalin A and lentil lectin affinity columns, were also similar to one of the two enzymes of normal pancreas. However, E-PHA lectin column chromatography demonstrated differences in their elution pattern. Compared with normal pancreatic gamma-GTPs, the elution pattern of the carcinoma gamma-GTP was slowly delayed by the E-PHA lectin column. This finding suggests the presence of a bisecting N-acetyl-glucosamine-rich sugar chain in pancreatic carcinoma gamma-GTP as well as the possible presence of a different sugar structure in the carcinoma gamma-GTP. Then we immunized Balb/c mice with those gamma-GTPs and the spleen cells from immunized mice fused with myeloma cell line. The hybridoma cells were screened for novel gamma-GTP by ELISA method and also the monoclonal antibodies were examined for specificity by the method of immunohistochemistry using human pancreatic cancer tissues. In future we are planning to use these developmental monoclonal antibodies for the mass screening of pancreatic cancer.