Discriminative value of isozymes of amino acid naphthylamidase in the diagnosis of myeloid leukemias.

Isozymes of amino acid naphthylamidase (called B and C) with deviating electrophoretic mobilities were found in peripheral blood leukocytes of 25 out 25 untreated acute and chronic myeloid leukemias (AML and CML) and in 2 out of 2 cases of idiopathic myelofibrosis, while a normal pattern was found in 3 control groups and 5 cases of polycythemia vera. In the AML group, a correlation between electrophoretic mobility and the number of blast cells was found, and on remission, the B isozyme mobility was nearly normalized. Thus, deviating electrophoretic mobility of the B isozyme seemed to be valuable for diagnosis of myeloid leukemias, and in the AML group, the change in mobility might indicate the size of the leukemic clone.