The diagnostic value of certain alkaline phosphatase isoenzyme patterns in human serum, fractions obtained by polyacrylamide disc electrophoresis.

Over 2500 pathological sera were analysed to determine alkaline phosphatase (EC 3.1.3.1) isoenzyme levels. 3% of these sera showed two or more narrow isoenzyme bands with a lower electrophoretic mobility on polyacrylamide than that of the intestine type of alkaline phosphatase and higher than that of the bile type of alkaline phosphatase (the extra-bands group). This latter group showed significantly more intestine-tupe alkaline phosphatase than a control group of 240 sera lacking extra serum bands. Significantly more of the individuals in the extra-bands group belonged to blood group O or B than did individuals of the control group. This relationship with blood groups suggests that the presence of the extra bands is genetically determined. It is concluded that the presence of these extra bands is not a specific indication for a particular disease or malignant process. The serum of seven patients showed an unusually strong alkaline phosphatase band with a relative mobility amounting to about one-third of that of the liver-type band (2nd fraction group). Specificity for a particular disease could not be established in this group either. In four patients the serum showed an alkaline phosphatase band with an electrophoretic mobility greater than that of the liver-tupe band (6th fraction group). All of these patients had liver metastases of a primary adenocarcinoma localized in the pancreas or stomach. After the demonstration of this fraction in ther serum, the course became progessively worse.