ABNORMAL ALKALINE-PHOSPHATASE OF HEPATIC TYPE IN CEREBROSPINAL-FLUID OF A PATIENT WITH INTRACRANIAL METASTASIS FROM LUNG-CANCER

High alkaline phosphatase (ALP) activity was found in the cerebrospina l fluid of a patient with intracranial metastases from adenocarcinoma of the lung. On agarose gel electrophoresis of the major ALP isoenzyme found in the cerebrospinal fluid, its mobility was different from tho se of the usual serum ALP isoenzymes. This abnormal mobility might be due to the linked glycan phosphatidylinositol anchor in the ALP molecu le, as the mobility became the same as that of the common liver type A LP after treatment with phosphatidylinositol specific phospholipase. T he immunochemical antigenicity of the cerebrospinal fluid ALP was iden tical with that of the common serum liver type ALP, but its sugar moie ty was similar to the membranous liver-type ALP rather than the serum liver type ALP. The molecular size of the cerebrospinal fluid ALP was 140 kilodaltons, 12 less than the common serum liver type ALP, suggest ing that the ALP in the patient's cerebrospinal fluid was derived from the intracranial metastatic carcinoma.