Salivary-type hyperamylasemia in primary lung cancer: observation of a possible precursor of the salivary-type isoamylase.

Although recent studies by column chromatography and electrophoresis showed that elevated amylase activity in the body fluids and tumor extracts in patients with primary lung cancer was mainly in the salivary-type isoamylase, neither mechanism nor mature of elevation of amylase have been clarified yet. This study was undertaken in order to make clear the nature of amylase elevated in the body fluids and tumor extracts of patients with primary lung cancer. In addition, amylase contained in the extracts of normal lungs and diseased lungs of patients who had died of various diseases was also studied. Our results revealed that amylase elevated in the body fluids and tumor extracts in patients with primary lung cancer was the salivary-type isoamylase and, moreover, that small amounts of salivary-type isoamylase in normal lung tissues and large amounts in diseased lung tissues were also contained. These facts suggested that salivary-type isoamylase was physiologically contained in normal lung tissues and large amounts in diseased lung tissues were also contained. These facts suggested that salivary-type isoamylase was physiologically contained in normal lung tissues and might be activated through pathological processes, such as inflammation, circulatory disturbance or tumor formation. Two peculiar isoamylases with cathodic mobility on polyacrylamide gel electrophoresis were found. One of them was so unstable that it was converted to the stable salivary-type isoamylase, suggesting the precursor of human salivary isoamylase.