A VARIANT ALKALINE-PHOSPHATASE FOUND IN A CASE OF GASTRIC-CARCINOMA WITH SUPER BONE-SCAN

A rare case of gastric carcinoma associated with increased serum varia nt alkaline phosphatase activities is presented. A 54 year old man had extremely high serum alkaline phosphatase activity (18 607 U/l) with normal calcium and phosphate concentrations. His bone scintigram showe d abnormal findings, 'super bone scan'. He was diagnosed as having Bor rmann type 4 gastric carcinoma with diffuse bone metastases by examina tions of the upper gastrointestinal tract and iliac bone biopsy. The a lkaline phosphatase isozyme of this patient was of the bone type as me asured by cellulose acetate membrane electrophoresis and the placenta/ bone type by agarose gel electrophoresis, respectively, Immunoelectrop horesis and the immunoprecipitation method using monoclonal antibodies against various alkaline phosphatase isozymes, however, showed that h is serum alkaline phosphatase had the liver type antigenicity. Further more, it had a larger molecular size and different sugar chains compar ed with the common liver type alkaline phosphatase. These findings sug gest that a unique variant alkaline phosphatase was produced by gastri c cancer cells, which is possibly an explanation for the high serum al kaline phosphatase activities in this patient.